United Stales
Environmental Protection
Agency
Research and Development
Office of Energy, Minerals, and
Industry
Washington DC 20460
EPA i
Man
Energy from the
West
Energy Resource
Development
Systems Report
Volume VI:
Geothermal
Interagency
Energy/Environment
R&D Program
Report
z
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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Energy From the West
Energy Resource Development
Systems Report
Volume VI: Geothermal
By
Science and Public Policy Program
University of Oklahoma
IrvinL. White Edward J. Malecki
Michael A. Chartock Edward B. Rappaport
R. Leon Leonard Robert W. Rycroft
Steven C. Ballard Rodney K. Freed
Martha Gilliland Gary D. Miller
Timothy A. Hall
Managers,
Energy Resource Development Systems
R. Leon Leonard, Science and Public Policy
University of Oklahoma
Clinton E. Burklin
C. Patrick Bartosh Gary D. Jones
Clinton E. Burklin William J. Moltz
William R. Hearn Patrick J. Murin
Prepared for:
Office of Research and Development
U. S. Environmental Protection Agency
Washington, D.C. 10460
Project Officer:
Steven E. Plotkin
Office of Energy, Minerals and Industry
Contract Number 68-01-1916
4fv>
Vfcst
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DISCLAIMER
This report has been reviewed by the Office of Energy,
Minerals and Industry, U.S. Environmental Protection Agency,
and approved for publication. Approval does not signify that
the contents necessarily reflect the views and policies of the
U.S. Environmental Protection Agency, nor does mention of trade
names or commercial products constitute endorsement or recommen-
dation for use.
ii
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FORWARD
The production of electricity and fossil fuels inevitably
impacts Man and his environment. The nature of these impacts
must be thoroughly understood if balanced judgements concerning
future energy development in the United States are to be made.
The Office of Energy, Minerals and Industry (OEMI), in its role
as coordinator of the Federal Energy/Environment Research and
Development Program, is responsible for producing the informa-
tion on health and ecological effects - and methods for miti-
gating the adverse effects - that is critical to developing the
Nation's environmental and energy policy. OEMI's Integrated
Assessment Program combines the results of research projects
within the Energy/Environment Program with research on the
socioeconomic and political/institutional aspects of energy
development, and conducts policy - oriented studies to identify
the tradeoffs among alternative energy technologies, development
patterns, and impact mitigation measures.
The Integrated Assessment Program has supported several
"technology assessments" in fulfilling its mission. Assess-
ments have been supported which explore the impact of future
energy development on both a nationwide and a regional scale.
Current assessments include national assessments of future
development of the electric utility industry and of advanced
coal technologies (such as fluidized bed combustion). Also,
the Program is conducting assessments concerned with multiple-
resource development in two "energy .resource areas":
o Western coal states
o Lower Ohio River Basin
This report, which describes the technologies likely to be
used for developing six energy resources in eight western
states, is one of three major reports produced by the "Tech-
nology Assessment of Western Energy Resource Development"
study. (The other two reports are an impact analysis report
and a policy analysis report.) The report is divided into six
volumes. The first volume describes the study, the organization
of this report and briefly outlines laws and regulations which
affect the development of more than one of the six resources
considered in the study. The remaining five volumes are resource
specific and describe the resource base, the technological
activities such as exploration, extraction and conversion for
developing the resource, and resource specific laws and regula-
iii
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tions. This report is both a compendium of information and a
planning handbook. The descriptions of the various energy
development technologies and the extensive compilations of
technical baseline information are written to be easily under-
stood by laypersons. Both professional planners, and interested
citizens should find it quite easy to use the information
presented in this report to make general but useful comparisons
of energy technologies and energy development alternatives,
especially when this report is used in conjunction with the
impact and policy analysis reports mentioned above.
Your review and comments on these reports are welcome.
Such comments will help us to improve the usefulness of the
products produced by our Integrated Assessment Program.
Steven R. Rezii£k
Acting Deputy Assistant Administrator
for Energy, Minerals and Industry
iv
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PREFACE
This Energy Resource Development System (ERDS) report has
been prepared as part of "A Technology Assessment of Western
Energy Resource Development" being conducted by an interdisciplin-
ary research team from the Science and Public Policy Program
(S&PP) of the University of Oklahoma for the Office of Energy,
Minerals and Industry (OEMI), Office of Research and Development,
U.S. Environmental Protection Agency (EPA) . This study is one of
several conducted under the Integrated Assessment Program estab-
lished by OEMI in 1975. Recommended by an interagency task
force, the purpose of the Program is to identify economically,
environmentally, and socially acceptable energy development
alternatives. The overall purposes of this particular study were
to identify and analyze a broad range of consequences of energy
resource development in the western U.S. and to evaluate and
compare alternative courses of action for dealing with the pro-
blems and issues either raised or likely to be raised by develop-
ment of these resources.
The Project Director was Irvin L.(Jack) White, Assistant
Director of S&PP and Professor of Political Science at the Univers-
ity of Oklahoma. White is now Special Assistant to Dr. Stephen
J. Gage, EPA's Assistant Administrator for Research and Develop-
ment. R. Leon Leonard, now a senior scientist with Radian Corpora-
tion in Austin, Texas, was a Co-Director of the research team,
Associate Professor of Aeronautical, Mechanical, and Nuclear
Engineering and a Research Fellow in S&PP at the University of
Oklahoma. Leonard was responsible for editing and managing the
production of this report. EPA Project Officer was Steven E.
Plotkin, Office of Energy, Minerals and Industry, Office of
Research and Development. Plotkin is now with the Office of
Technology Assessment. Other S&PP team members are: Michael A.
Chartock, Assistant Professor of Zoology and Research Fellow in
S&PP and the other Co-Director of the team; Steven C. Ballard,
Assistant Professor of Political Science and Research Fellow in
S&PP; Edward J. Malecki, Assistant Professor of Geography and
Research Fellow in S&PP; Edward B. Rappaport, Visiting Assistant
Professor of Economics and Research Fellow in S&PP; Frank J.
Calzonetti, Research Associate (Geography) in S&PP; Timothy A.
Hall, Research Associate (Political Science); Gary D. Miller,
Graduate Research Assistant (Civil Engineering and Environmental
Sciences); and Mark S. Eckert, Graduate Research Assistant (Geo-
graphy) .
-------
Chapters 3-7 were prepared by the Radian Corporation, Austin,
Texas, under subcontract to the University of Oklahoma. In each
of these chapters. Radian is primarily responsible for the des-
cription of the resource base and the technologies and S&PP is
primarily responsible for the description of laws and regulations.
The Program Manager at Radian was C. Patrick Bartosh. Clinton
E. Burklin was responsible for preparation of these five chapters.
Other contributors at Radian were: William R. Hearn, Gary D.
Jones, William J. Holtz, and Patrick J. Murin.
Additional assistance in the preparation of the ERDS report
was provided by Martha W. Gilliland, Executive Director, Energy
Policies Studies, Inc., El Paso, Texas; Rodney K. Freed, Attorney,
Shawnee, Oklahoma; and Robert W. Rycroft, Assistant Professor of
Political Science, University of Denver, Denver, Colorado.
vi
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ABSTRACT
This report describes the technologies likely to be used
for development of coal, oil shale, uranium, oil, natural gas,
and geothermal resources in eight western states (Arizona, Color-
ado, Montana, New Mexico, North Dakota, South Dakota, Utah,
and Wyoming). It is part of a three-year "Technology Assess-
ment of Western Energy Resource Development." The study examines
the development of these energy resources in the eight states
from the present to the year 2000. Other reports describe
the analytic structure and conduct of the study, the impacts
likely to result when these resources are developed, and analyze
policy problems and issues likely to result from that develop-
ment. The report is published in six volumes. Volume 1 describes
the study, the technological activities such as exploration,
extraction, and conversion for developing the resource, and
laws and regulations which affect the development of more
than one of the six resources considered in the study. The
remaining five volumes are resource specific: Volume 2, Coal;
Volume 3, Oil Shale; Volume 4, Uranium; Volume 5, Oil and Natural
Gas; and Volume 6, Geothermal. Each of these volumes provides
information on input materials and labor requirements, outputs,
residuals, energy requirements, economic costs, and resource
specific state and federal laws and regulations.
vii
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OVERALL TABLE OF CONTENTS
FOR
THE ENERGY RESOURCE DEVELOPMENT SYSTEMS REPORT
VOLUME I: INTRODUCTION AND GENERAL SOCIAL CONTROLS
Chapter 1 ENERGY RESOURCE DEVELOPMENT SYSTEMS
1.1 Introduction
1.2 Objectives of the ERDS Document....
1.3 Organization of the ERDS Document..
1.4 Limitations of the ERDS Document...
Chapter 2 GENERAL SOCIAL CONTROLS
PAGE
1
3
4
9
2.1 Introduction 11
2.2 Environmental Impact Statements.... 11
2.3 Siting and Land Use 19
2.4 Resource Exploration 29
2.~5 Resource Acquisition. 38
2.6 Resource Extraction 48
2.7 Occupational Safety and Health 59
2.8 Air Quality; : 65
2.9 Water Quality 95
2.10 Water Use 109
2.11 Solid Waste Disposal 135
2.12 Noise Pollution 139
2.13 Transportation and Distribution.... 145
2.14 Conclusions 153
VOLUME II: COAL
Chapter 3 THE COAL RESOURCE DEVELOPMENT SYSTEM
3.1 Introduction 1
3.2 Summary 3
3.3 Coal Resources 12
3.4 A Regional Overview 27
3.5 Exploration 37
3.6 Mining 52
3.7 Benef iciation 139
3.8 Conversion 174
viii
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OVERALL TABLE OF CONTENTS
(continued)
VOLUME III: OIL SHALE PAGE
Chapter 4 THE OIL SHALE RESOURCE DEVELOPMENT SYSTEM
4.1 Introduction 1
4.2 Summary 4
4.3 Resdurce Description 13
4.4 Exploration.. 25
4.5 Mining and Preparation 37
4.6 Processing 142
4.7 Land Reclamation 297
VOLUME IV: URANIUM
Chapter 5 THE URANIUM RESOURCE SYSTEM
5.1 Introduction 1
5.2 Uranium Resources 8
5.3 Exploration 31
5.4 Mining. 64
5.5 Uranium Milling 197
VOLUME V: OIL AND NATURAL GAS
Chapter 6 CRUDE OIL RESOURCE DEVELOPMENT SYSTEM
6.1 Introduction 1
6.2 Resource Description of Western
Crude Oil 8
6.3 Exploration 14
6.4 Crude Oil Production 57
6.5 Transportation 144
Chapter 7 THE NATURAL GAS RESOURCE DEVELOPMENT SYSTEM
7.1 Introduction 146
7.2 Resource Description of the Western
Natural Gas 151
7.3 Exploration 157
7.4 Natural Gas Production 165
7.5 Transportation.... 201
ix
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OVERALL TABLE OF CONTENTS
(continued)
VOLUME VI: GEOTHERMAL PAGE
Chapter 8 THE GEOTHERMAL RESOURCE DEVELOPMENT SYSTEM
8.1 Introduction 1
8.2 Summary 6
8.3 Resource Characteristics 13
8.4 Exploration 40
8.5 Extraction: Drilling 68
8.6 Extraction: Production 113
8.7 Uses of Geothermal Energy 146
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TABLE OF CONTENTS
VOLUME VI
CHAPTER 8: THE GEOTHERMAL RESOURCE DEVELOPMENT SYSTEM Page
FOREWORD i
8.1 INTRODUCTION 1
8.2 SUMMARY 6
8. 3 RESOURCE CHARACTERISTICS 13
8.3.1 Geology 13
8.3.2 Location 20
8.3.3 Quantity 25
8.3.4 Physical and Chemical Characteristics 32
8.3.5 Ownership 35
8.4 EXPLORATION 40
8.4.1 Technologies 40
8.4.2 Input Requirements 46
8.4.3 Outputs 54
8.4.4 Exploration Social Controls 60
8.5 EXTRACTION: DRILLING 68
8.5.1 Technologies 68
8.5.2 Input Requirements 74
8.5.3 Outputs -. - 89
8.5.4 Social Controls for Obtaining Lands 100
8.6 EXTRACTION: PRODUCTION 113
8.6.1 Technologies 113
8.6.2 Input Requirements 117
8.6.3 Outputs 126
8.6.4 Extraction Social Controls 128
xi
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TABLE OF CONTENTS (Continued)
VOLUME VI
Page
8. 7 USES OF GEOTHERMAL ENERGY 146
8. 7.1 Electric Power Generation 147
8.7.2 Input Requirements 161
8.7.3 Outputs 175
8.7.4 Direct Thermal and Other Uses of
Geothermal Energy . 185
xii
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LIST OF FIGURES
VOLUME VI
CHAPTER 8: THE GEOTHERMAL RESOURCE DEVELOPMENT SYSTEM
Number Page
8-1 Geothermal Energy Development 5
8-2 Structure of a Typical Hydrothermal
Convection System 15
8-3 Distribution of U.S. Geothermal Resources 21
8-4 The Location of Known Geothermal Resource
Areas in the Eight Western States 22
8-5 Ranges of Chemical Constituent Concentrations
in Geothermal Fluids , MG/L 33
8-6 Typical Well Configuration at The Geysers 71
8-7 Geothermal Well Costs as a Function of Depth .. 82
8-8 Dry Rock Geothermal Energy System by
Hydraulic Fracturing 116
8-9 Simplified Schematic of a Dry Steam Energy
Conversion System 148
8-10 Simplified Schematic of a Two-Stage
Flashed Steam Energy Cpnversion System 152
8-11 A Schematic Diagram of a Binary Cycle
Energy Conversion System 155
8-12 Recommended Temperature of Geothermal Fluids
for Various Direct Thermal and Other
Non-Electrical Applications 188
xiii
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LIST OP TABLES
VOLUME VI
CHAPTER 8: THE GEOTHERMAL RESOURCE DEVELOPMENT SYSTEM
Number Page
8-1 SUMMARY OF INPUTS AND OUTPUTS OF AN
EXPLORATION EFFORT INTENDED TO DISCOVER A
FIELD SUFFICIENT TO PRODUCE 100 MW ELECTRIC
POWER 7 7
8-2 SUMMARY OF INPUTS AND OUTPUTS OF DRILLING
WELLS SUFFICIENT FOR THE PRODUCTION OF
100 MW^ ELECTRIC POWER 9
e
8-3 SUMMARY OF INPUTS AND OUTPUTS ASSOCIATED
WITH WELLHEAD PRODUCTION SYSTEM AT A 100 MW
POWER PLANT , 7... 11
8-4 SUMMARY OF INPUTS AND OUTPUTS OF A GEOTHERMAL
POWER PLANT PRODUCING 100 MWe 12
8-5 ESTIMATED HEAT CONTENT OF GEOTHERMAL
RESOURCE BASE OF THE UNITED STATES 27
8-6 IDENTIFIED GEOTHERMAL AREAS OF THE EIGHT
WESTERN STATES 29
8-7 PROJECTIONS OF ELECTRICITY GENERATING CAPACITY
FROM GEOTHERMAL RESOURCES IN THE UNITED STATES,
1985-2000 30
8-8 INTENDED COMMERCIAL DEVELOPMENT OF GEOTHERMAL
ENERGY GIVEN SUCCESSFUL IMPLEMENTATION OF
FEDERAL PROGRAM 31
8-9 CHARACTERISTICS OF TWO U.S. GEOTHERMAL FIELDS 36
8-10 CHARACTERISTICS OF GEOTHERMAL FLUIDS FROM A
WELL IN SANDOVAL COUNTY, NEW MEXICO 37
8-11 CHARACTERISTICS OF LIQUIDS FROM WELLS AT
ROOSEVELT HOT SPRINGS IN BEAVER COUNTY, UTAH .. 38
8-12 STATUS OF GEOTHERMAL LEASES AS OF
OCTOBER 31, 1976 39
8-13 MANPOWER REQUIREMENTS FOR EXPLORATION AND
APPRAISAL OF A HOT WATER FIELD WITH A CAPACITY
FOR THE PRODUCTION OF 100 MW ELECTRIC POWER . . 48
xiv
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LIST OP TABLES (Continued)
VOLUME VI
Number Page
8-14 EXPLORATION COSTS TO PROVE A HOT WATER FIELD
CAPABLE OF THE PRODUCTION OF 200 MW
ELECTRIC POWER e 50
8-15 EXPLORATION COSTS FOR A THREE YEART EXPLORATION
PROGRAM DEFINING A FIELD SUFFICIENT FOR A
200 MWe POWER GENERATING FACILITY . 52
8-16 AIR EMISSIONS DURING EXPLORATORY DRILLING ... 55
8-17 NOISE LEVELS DURING THE EXPLORATORY DRILLING
OF GEOTHERMAL RESOURCES f, 59
8-18 SUMMARY OF INPUTS AND OUTPUTS OF AN
EXPLORATION EFFORT INTENDED TO DISCOVER A
FIELD SUFFICIENT TO PRODUCE 100 MW0 ELECTRIC
POWER 7 61
8-19 CLASSIFICATION OF GEOTHERMAL RESOURCES 64
8-20 EXPLORATION OF STATE LANDS FOR GEOTHERMAL
RESOURCES FOR NON-KGRA LANDS 67
8-21 WELL REQUIREMENTS FOR THE PRODUCTION OF
100 MWe ELECTRIC POWER 78
8-22 MANPOWER REQUIREMENTS FOR THE DRILLING OF
WELLS SUFFICIENT FOR THE PRODUCTION OF
100 MWe ELECTRIC POWER 80
8-23 COMPONENT COSTS OF A COMPLETED STEAM WELL
SUNK TO A DEPTH OF 8000 FEET 84
8-24 ESTIMATED WELL COSTS FOR THE PRODUCTION OF
100 MWe ELECTRIC POWER . 85
8-25 ESTIMATED WATER REQUIREMENTS FOR DRILLING
WELLS SUFFICIENT TO PRODUCE 100 MW.
ELECTRIC POWER 7 87
8-26 ESTIMATED LAND DISTURBANCE AND REQUIREMENTS
FOR DRILLING WELLS SUFFICIENT TO PRODUCE
100 MW_ ELECTRIC POWER 88
e
xv
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LIST OF TABLES (Continued)
VOLUME VI
Number Page
8-27 ESTIMATED ENERGY REQUIREMENTS FOR DRILLING
WELLS SUFFICIENT TO PRODUCE 100 MW
ELECTRIC POWER 7 90
8-28 TOTAL AIR EMISSIONS FROM THE OPERATION OF
DIESEL GENERATORS DURING DRILLING OF
GEOTHERMAL WELLS SUFFICIENT TO PRODUCE
100 MW ELECTRIC POWER 92
e
8-29 TOTAL EMISSIONS OF GEOTHERMAL STEAM DURING
DRILLING, CLEAN-OUT, AND PRODUCTION AT THE
GEYSERS FOR A WELL CAPACITY OF 100 MW
IN ELECTRIC POWER 7 94
8-30 ESTIMATED QUANTITIES OF WATER EFFLUENTS
PRODUCED DURING DRILLING AND TESTING OF WELLS
SUFFICIENT FOR THE PRODUCTION OF 100 MW
8-31
8-32
8-33
8-34
8-35
8-36
8-37
8-38
8-39
8-40
8-41
SUMMARY OF INPUTS AND OUTPUTS OF DRILLING
WELLS SUFFICIENT FOR THE PRODUCTION OF
100 MW ELECTRIC POWER
SUMMARY OF LEASING FEATURES FOR FEDERAL LANDS
COMPETITIVE LEASING PROCEDURES FOR KNOWN AREAS
ARIZONA GEOTHERMAL LEASE FEATURES
COLORADO GEOTHERMAL LEASE FEATURES
MONTANA GEOTHERMAL LEASE FEATURES
NEW MEXICO GEOTHERMAL LEASE FEATURES
UTAH GEOTHERMAL LEASE FEATURES
WYOMING GEOTHERMAL LEASE FEATURES
PRODUCTION AND RESERVE WELL REQUIREMENTS FOR
THE GENERATION OF 100 MW ELECTRIC POWER
e
MANPOWER REQUIRED TO CONSTRUCT A GATHERING
SYSTEM SUPPLYING A 100 MW. POWER PLANT
101
104
107
108
108
109
110
111
112
118
119
xvi
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LIST OF TABLES (Continued)
VOLUME VI
Number
8-42
8-43
8-44
8-45
8-46
8-47
8-48
8-49
8-50
8-51
8-52
8-53
8-54
8-55
MANPOWER REQUIRED TO OPERATE AND MAINTAIN A
GATHERING SYSTEM SUPPLYING A 100 MtT
POWER PLANT f
COST ESTIMATING FACTORS FOR PIPING AS A
FUNCTION OF DRILLING COSTS
ESTIMATED COSTS OF WELL-HEAD PRODUCTION
SYSTEMS SUPPLYING A 100 MW POWER PLANT
e
SUMMARY OF INPUTS AND OUTPUTS ASSOCIATED WITH
WELLHEAD PRODUCTION SYSTEM AT A 100 MW
POWER PLANT f
REGULATORY MECHANISMS IN THE STATES FOR
GEOTHERMAL DEVELOPMENT
CLASSES OF EXPANDERS DEVELOPED OR CONSIDERED
FOR TOTAL FLOW APPLICATIONS
MANPOWER REQUIRED TO CONSTRUCT A RE INJECTION
PIPING NETWORK ASSOCIATED WITH A 100 MW^
POWER PLANT ®
MANPOWER REQUIRED TO CONSTRUCT A 100 MW
GEOTHERMAL POWER PLANT ?
MANPOWER REQUIRED TO OPERATE AND MAINTAIN A
REINJECTION PIPING NETWORK ASSOCIATED WITH A
100 MWe POWER PLANT
MANPOWER REQUIRED TO OPERATE AND MAINTAIN A
100 MW GEOTHERMAL STEAM POWER PLANT
e
MANPOWER REQUIRED TO OPERATE AND MAINTAIN A
100 MW HOT WATER OR BRINE POWER PLANT
ESTIMATED CAPITAL COSTS OF POWER PLANT (AND
ASSOCIATED REINJECTION PIPING NETWORK)
PRODUCING 100 MWe ELECTRIC POWER
COST SUMMARY FOR THE PRODUCTION OF ELECTRICITY
FROM 100 MWg HOT WATER POWER PLANTS
COSTS FOR ELECTRICITY GENERATED FROM THREE
REPRESENTATIVE HOT WATER RESERVOIRS
u
120
122
124
129
133
160
163
164
165
166
167
169
171
172
xvii
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LIST OF TABLES (Continued)
VOLUME VI
Number Page
8-56 UNCONTROLLED EMISSIONS OF NONCONDENSABLE GASES
AND SOLID MATERIALS FROM THE POWER GENERATING
UNITS AT THE GEYSERS POWER PLANT 177
8-57 CONCENTRATIONS OF VARIOUS CHEMICAL SPECIES IN
NONCONDENSABLE EMISSIONS FROM NILAND TEST
8-58
8-59
8-60
8-61
FACILITY
WATER EFFLUENTS PRODUCED DURING POWER
PRODUCTION AT A 100 MW POWER PLANT
SUMMARY OF INPUTS AND OUTPUTS OF A
GEOTHERMAL POWER PLANT PRODUCING 100 MWe
PRESENT INDUSTRIAL APPLICATIONS OF GEOTHERMAL
ENERGY
ESTIMATED COSTS OF NON-ELECTRICAL UTILIZATIONS
OF GEOTHERMAL ENERGY
181
183
186
194
196
xviii
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CONVERSION FACTORS
English Units/Metrie Units
To Convert From
acre
acre-ft/year
acre-ft/year
barrel
barrel
Btu
Btu/hour
Btu/pound
foot
gallon
Ib
psi
quad
quad
ton
To
m2
gpm
tn'/yr
gal
m3
joule
watt
joule/gram
m
m3
kg
pascal
Btu
joule
kg
Multiply By
4046.9
0.6200
1233.5
42
0.15899
1054.4
0.2931
2.32
0.3048
0.003785
0.4536
6894.8
10ls
907.18
xix
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ACKNOWLEDGEMENTS
Patrick J. Murin of the Radian Corporation and Gary D. Miller
of the Science and Public Policy Program at the University of
Oklahoma had primary responsibility for preparation of this vol-
ume of the Energy Resource Development Systems (ERDS) Report.
The social controls sections were prepared by Rodney K. Freed
and R. Leon Leonard of the Science and Public Policy Program.
Mr. Freed is now an attorney in Shawnee, Oklahoma and Dr. Leonard
is now a senior scientist with the Radian Corporation in Austin,
Texas.
The research reported here could not have been completed with-
out the assistance of a dedicated administrative support staff.
At Radian Corporation, Mary Harris was responsible for typing of
this volume, and at the University of Oklahoma, Janice Whinery,
Assistant to the Director, coordinated assembly of the volumes of
the ERDS Report.
Nancy Ballard, graphics arts consultant, designed the title
page.
Steven E. Plotkin, EPA Project Officer, has provided con-
tinuing support and assistance in the preparation of this report.
The individuals listed below participated in the review of
this volume of the ERDS Report and provided information for its
preparation. Although these critiques were extremely helpful,
none of these individuals is responsible for the content of this
volume. This volume is the sole responsibility of the Science
and Public Policy interdisciplinary research team and the Radian
Corporation.
Mr. George Boulter Mr. Robert P. Hartley
Office of Energy Activities Program Manager for Qeothermal
Environmental 'Protection Agency Energy
Region VIII Industrial Environmental
Denver, Colorado Research Laboratory
Environmental Protection Agency
Cincinnati, Ohio
xx
-------
Dr. John Hoover
Energy and Environmental
Systems
Argonne National Laboratory
Chicago, Illinois
Dr. Frank MasIan
Office of Technology Assessment
U.S. Congress
Washington, D.C.
Mr. Robert Oliver
Program Manager, Planning
Branch
Division of Geothermal Energy
Department of Energy
Washington, D.C.
Dr. D.R. Rao
New Mexico Energy Institute
New Mexico State University
Las Cruces, New Mexico
Mr. Douglas M. Sacarto
Associate Director
Geothermal Policy Project
National Conference of
State Legislatures
Denver, Colorado
Dr. Morton C..-Smith
Geosciences Division
Los Alamos Scientific Laboratory
Los Alamos, New Mexico
Dr. Kenneth Starling
School of Chemical Engineering
and Materials Sciences
University of Oklahoma
Norman, Oklahoma
Mr. Randy Stevens
Division of Geothermal Energy
Department of Energy
Washington, D.C.
xxi
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CHAPTER 8
THE GEOTHERMAL RESOURCE DEVELOPMENT SYSTEM
8.1 INTRODUCTION
This document is one of several reports issued in support
of a "Technology Assessment of Western Energy Resource Develop-
ment," a project jointly conducted by the Science and Public
Policy Program of the University of Oklahoma and the Radian
Corporation of Austin, Texas. The project is funded by the
Office of Energy, Minerals, and Industry, Office of Research
and Development, Environmental Protection Agency under Contract
68-01-1916. The "Technology Assessment of Western Energy Re-
source Development" describes the development of energy re-
sources in eight western states. These states are: Arizona,
Colorado, Montana, New Mexico, North Dakota, South Dakota,
Utah, and Wyoming.
This document is issued as Chapter 8 of the "Energy
Resources Development System" (ERDS) report. For each of six
energy resources, the ERDS report describes the energy resource
base, the technologies used to develop and utilize the resource,
the inputs and outputs for each development technology, and the
laws and regulations applying to the 'deployment and operation
of each technology. Resources described in the ERDS report
are: coal, oil shale, uranium, oil, natural gas, and geother-
mal energy. This chapter discusses the development of the geo-
thermal energy resource.
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In the broadest terms, geothermal energy can be defined
as heat emanating from the earth. This heat is derived from
the decay of radioactive elements (chiefly uranium and thorium),
friction (tidal and crustal plate motion), and possibly primeval
heat. Localized areas of concentrated heat may form as the heat
flows radially outward. In certain regions of the earth's crust,
these areas of concentrated heat may be used for electricity
generation or as a source of low grade heat.
Man has known about goethermal energy since ancient times.
The Romans used hot geysers for baths and for space heating.
The Italians were extracting boric acid from steam jets near
Larderello, Italy, in the 19th century. Use of the Larderello
steam jets for electricity generation began in 1904.
The United States first used geothermal energy for elec-
tricity generation in 1960 at The Geysers area in California.
To date, The Geysers area remains the only site of commercial
electricity production from geothermal energy in the U.S.
Pacific Gas and Electric Company currently is generating about
500 megawatts from The Geysers dry steam field. By 1985, pro-
duction at The Geysers is expected to amount to 1800-2130 MW
Additional electricity production from other geothermal resources
is expected to amount to 1220-1960 MWe by 1985.I>2 With these
and other additions, geothermal energy may provide about one
percent (under very favorable conditions, several percent) of
1Resources Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy. Prepared
for U.S. Environmental Protection Agency.Contract No. 68-01-4100
Washington, B.C.: U.S. Environmental Protection Agency, May 1977,
pp. 15, 16, 19, 25.
2LaMori, Phillip N. "Growth in Utilization of Hydrothermal
Geothermal Resources." Geothermal Resources Council. Trans-
actions . Vol. 1. May 19TTpp. 181-182.
-2-
-------
the electricity production in the U.S. by the year 2000.
Although its national role is small, geothermal energy can be
a significant producer of electricity in certain local areas
(e.g., California).l
Geothermal resources may also be used for various direct
thermal or other nonelectric purposes. For example, fresh
water can be produced by condensing steam from liquid- or
vapor-dominated geothermal resources. Some geothermal fluids
contain significant quantities of extractable minerals. Direct
space heating with geothermal water is currently employed in the
U.S. at Klamath Falls, Oregon, and Boise, Idaho. Direct thermal
and other nonelectrical uses are most important in the utiliza-
tion of low-temperature geothermal fluids.
This chapter describes the technologies, inputs, outputs,
rules, and regulations associated with the development of geo-
thermal energy resources. The chapter comprises five major sec-
tions which begin with a general description of the geothermal
energy resource. The remaining sections describe the steps or
activities involved in developing geothermal energy.
Section 8.2 summarizes the input requirements and outputs
identified in this study as resulting from the development and
utilization of the western geothermal energy resource.
Section 8.3, Resource Characteristics, describes the
geothermal energy resource in terms of geology, location,
quantity, physical and chemical characteristics, and ownership.
Science and Public Policy Program, University of Oklahoma.
Energy Alternatives; A Comparative Analysis. Prepared for CEQ
ERDA, EPA, FEA, FPC, DOI, NSF, CEQ Contract No. EQ4AC034.
Washington, D.C.: U.S. Government Printing Office. May 1975,
p. 8-1.
-3-
-------
The remaining sections (Sections 8.4 through 8.7) describe
the development of geothermal energy as a basic sequence of
"activities". In the development of geothermal energy resources,
these activities include: exploration, extraction (both drilling
and production phases), and electricity generation or nonelectric
utilizations. These activities are illustrated in Figure 8-1.
For each activity, "technological alternatives" are discussed
which represent potential development options (e.g., various
drilling technologies).
When available, input requirements and outputs for each
technological alternative or activity are presented. Input
requirements discussed in this report include: manpower,
materials and equipment, economics, water, land, and ancillary
energy. The outputs describe the residuals from each activity
or technological alternative that may pose environmental hazards.
The outputs described in the report are air emissions, water
effluents, solid wastes, noise pollution, occupational health
and safety hazards, and odor. Social controls (i.e., laws and
regulations) governing the development of geothermal energy
resources are also discussed.
Input requirements and outputs reported herein mostly
describe vapor-dominated geothermal fluids used for electricity
generation. Liquid-dominated fluids offer greater potential
for both electrical and other uses. However, use of. liquid-
dominated' resources is relatively undeveloped in the United
States. Other geothermal resources (e.g., hot dry rock re-
sources) are also relatively undeveloped. When possible,
inputs and outputs for these undeveloped resources are repor-
ted.
-4-
-------
GEOTHERMAL ENERGY RESOURCES
VAPOR DOMINATED HYDROTHERMAL
LIQUID DOMINATED HYDROTHERMAL
HOT DRY ROCK
GEOPRESSURED
MAGMA
EXPLORATION
EXTRACTION
DRILLING
PRODUCTION
USES
ELECTRICITY
PRODUCTION
NONELECTRIC
UTILIZATIONS
DRY STEAM
FLASHED STEAM"
BINARY CYCLE
HYBRID
TOTAL FLOW
SPACE AND DISTRICT
HEATING/COOLING
AGRICULTURAL HEATING
AND IRRIGATION
INDUSTRIAL PROCESS
HEAT AND STEAM
MINERAL AND GAS
EXTRACTION
Figure 8-1. Geothermal Energy Development
-5-
-------
8.2 SUMMARY
The input requirements and outputs associated with each
phase of the geothermal energy resource development system are
summarized in Tables 8-1 through 8-4. The input requirements
include manpower, materials and equipment, economics, water,
land,, and ancillary energy. The outputs include air, water,
and solid waste emissions, noise, odors, and occupational
safety and health.
These summary tables present typical values for various
geothermal energy development options. The inputs and outputs
are based on little actual experience and should be interpreted
only as preliminary estimates. These inputs and outputs vary
over a wide range, depending on the characteristics of the geo-
thermal resource and the development technology. The assump-
tions used to develop these tables are described in detail in
their respective sections of the text.
-6-
-------
TABLE 8-1.
SUMMARY OF INPUTS AND OUTPUTS OF AN EXPLORATION
EFFORT INTENDED TO DISCOVER A FIELD SUFFICIENT
TO PRODUCE 100 MWg ELECTRIC POWER
Input Requirements
Manpower
• first year
second year
Materials and Equipment
Economics
Water
Land
temporary
• permanent
Ancillary energy
Outputs
Air emissions
steam
carbon dioxide
carbon monoxide
hydrocarbons
nitrogen oxides
aldehydes
sulfur oxides
particulates
ammonia
hydrogen sulfide
nitrogen and argon
hydrogen
15 man-years
21 man-years
Not quantified
$13 million
55 acre-feet
19 acres
less than 1 acre
1,700,000 gal. diesel fuel
355,000 tons
21,000 tons
87 tons
210 tons
400 tons
6 tons
27 tons
greater than 29 tons
250 tons
180 tons
110 tons
35 tons
11975 dollars
Over 18 months
(Continued)
-7-
-------
TABLE 8-1. SUMMARY OF INPUTS AND OUTPUTS OF AN EXPLORATION
EFFORT INTENDED TO DISCOVER A FIELD SUFFICIENT
TO PRODUCE 100 MWe ELECTRIC POWER (CONTINUED)
Water effluents
drilling mud 58 acre-feet
geothermal fluids 112 acre-feet
Solid wastes
drill cuttings 2 acre-feet
Noise pollution
- well cleaning 118 db(A)c
Occupational health and safety data unavailable
Odors H2S
NH3
C50 ft. distance
-8-
-------
I
vo
I
TABLE 8-2. SUMMARY OF INPUTS AND OUTPUTS OF DRILLING WELLS SUFFICIENT
FOR THE PRODUCTION OF 100 MWfi ELECTRIC POWER
Input KgijiilrucntB
Manpower
• firut year
• ueconU year
Material*
• steel
Economic B
Witter
Ijind
• temporarily disturbed
• required for well spacing
Ancillary Energy
Outputs
Air Imiaulona
• dieael generator*
carbon Monoxide
hydrocarbons
nitrogen oxides
aldehydes
BuKuc oxides
partlculates
carbon dioxide
Hot Water/Binary Cycle
ISO
29
18.000 tons
$43 Billion'
290 acre-ft
98 acres
990-4000 acres
8.9 MM gal dlesel fuel
450 tons
170 tons
2100 tons
31 tons
140 tons
150 tons
96,000 tons
Hot Nater/Steasi Plashing Cycle
170
32
20.000 tons
$47 million0
310 acre-ft
108 acres
1100-4300 seres
9.7 MM gal dlesel fuel
490 tons
180 tons
2300 eons
34 tons
150 tons
160 tons
100,000 tons
Hot Rock/Binary Cycle
17
3
2.000 tons
$13 Billion0
32 acre-ft
11 acres
110-440 acres
1 HH gal dleeel fuel
50 tons
19 tons
230 tons
3.5 tons
15 tons
17 tons
11,000 tons
Dry Slea«/Dlrect Dae
31-40°
6-8 "
15,000-20.000 tonsb
$20-26 •UUond>e.
$80-106 Million
58-75 acre-ft*
230-310 acre-ft
20-26 acres*
80-106 acres
800-1000 acres*
3200-4200 acres
1.8-2.3 m gal dleael fuel'
7.2-9.5 MM gal dlesel fuel
92-120 ions*
370-480 tons6
34-43 tons'
130-180 tons
420-540 tons"
1700-2200 tons
6.3-8.1 tons6
25-33 tons1
28-36 tons6
110-150 tons'
30-39 tons6
120-160 tons
19,000-25,000 tons6
78,000-100,000 tons
(Continued)
-------
TABLE 8-2.
SUMMARY OF INPUTS AND OUTPUTS OF DRILLING WELLS SUFFICIENT
FOR THE PRODUCTION OF 100 MWe ELECTRIC POWER (CONTINUED)
1— 1
o
1
t'r<*» gt'uc herau 1 fluldtf
Hi earn
carbon dioxide
uiuiinn 1 a
inetliane
hydrntjen tmlfide
nllrugeii and urgnn
hydrogen
W.itur Kf fluent a
• drill Ing mud
• geotliurnal fluids
Solid Wdsteu
• drill cuttings
Noltie Pollution
• blowouts (infrequent)
• wul 1-bl ceding (open hole)
Occupational Health and Safety
Odorb
Hot Water/Binary Cycle
1,330,000 tons
10,600 tons
940 cons
670 tons
670 tons
400 tons
130 tons
300 acre-f t
1300 acre-ft
10 acce-ft
US dB(A)
86 dB(A)
Not Quantified
H2S
NHi
Hot Uater/Steasi Ftaslilng Cycle Hot Rock/Binary Cycle
1,330,000 tons
10,600 tons
940 cons
670 tons
670 tons
400 tons
130 tons
320 acre-ft 33 acre-ft
1700 acre-ft
11 acre-ft 1 acre-ft
118 dB (A)
86 dB(A)
Not Quantified Not Quantified
HjS Unknown
HH)
Dry Steun/Ulrect Use
1,330,000 tons
10,600 tons
940 tons
670 tons
670 tons
400 tons
130 tons
60-78 acre-ft?
240-320 acre-ft
2-3 acre-ft'
8-11 acre-ft
118 dB(A)
86 dB(A)
Not Quantified
H2S
HH
Does nut Include annual drilling manpower requireaents.
b<)ver 30 year life.
CI976 dollars.
U1977 dollara.
"initial.
Over 30 years; Jncluden depletion.
"baaed on The Ceyueru.
-------
TABLE 8-3. SUMMARY OF INPUTS AND OUTPUTS ASSOCIATED WITH WELLHEAD
PRODUCTION SYSTEM AT A 100 MWfi POWER PLANT
tn put Requirements
Manpower
• construction
• operating
Materials
• steel
Economics
Water
Land
Ancillary Energy
Outputs
Air Emissions
Water Effluents
Solid Wastes
NolHU Pollution
production
• muffled vent
Occupational Health
und Safety
Odor
Hot Water/Binary Fluid
30 man-years
3 men
2,700 tona
$12 Billion
~
28 acrea
None-Variable
Small
Small
Undetermined
Little
90 db(A)
Not Quantified
NHj
HjS
Hot Water/Steam Flashing
33 man-years
3 men
3,000 tona
$13 Billion
—
30 acres
None-Variable
Small
Small
Undetermined
Little
90 db(A)
Not Quantified
HH,
H2S
Hot Rock/Binary Fluid
3 man-years
0.3 men
430 tona
$1.8 ailllon
2.5-5 acre-ft/d
3 acrea
Variable
Small
Small
Undetermined
Little
90 db(A)
Hot Quantified
Unknown
Dry Stean/Dlrect Use
11-14 man-years
43-58 man-years
-1.2 men
950-1300 tons"
3900-5300 tonsb
$6.1-$8 Billion8
$37-$50 million"
—
9-13 acres8
39-53 acresb
None-Variable
Small
Small
Undetermined
Little
90 db(A)
Not Quantified
NH)
H2S
initial
Over 30 yeara
cAt 90 feet
-------
TABLE 8-4. SUMMARY OF INPUTS AND OUTPUTS OF A GEOTHERMAL
POWER PLANT PRODUCING 100 MW
Hot Water/Binary Fluid Hot Water/Steam Flashing Hot Rock/Binary Fluid Dry Steam/Direct U«e
Input Requirement
Manpower
• construction
' operating
Material*
• steel la piping network
Economic*
• capital cost**
• power generation costs
Water
• total make-up
Tjnrf
Ancillary Energy
257 man-year*
28 men
2200 ton*
$66.4 million
3.1c/kW»c
13,000 acre-ft/yr"
31 acre*
260 man-year*
28 men
2400 ton*
$131.4 million
*.7c/kWhC
13,000 acre-ft/yr*
37 acres
Hone
230 man-year*
26 men
360 tons
$40.9 million
1.6c/kWhC
13,000 acre-ft/yr*
12 acre*
Hone
170 man-year*
8 mm
40 Con*;
2.0c/nft>
Hone
4 acre*
Ben*
Output*
Air BelMion*
• carbon dioxide
• hydrogen (ulflde
hydrogen
Unknown
Unknown
Unknown
5500 lb/hr
380 lb/hr
330 lb/hr
80 lb/hr
330 lb/hr
• anenlc
• boron
• mercury
Water Effluent*
• blowdovn
• spent brine
Solid Wa*te*
Holla Foliation
Occupational Health
and Safety
Odor*
Based on 150 C resource.
3.000 acre-ft/yr
51,000 acre-ft/yr
Sot Quantified
90 dB(A)
Vot Qumntified
MB,
HjS
Including capital charge.
3,000 acre-ft/yr
52,000 acre-ft/yr
Rot Quantified
90 d»(A)
Hot Quantified
SB,
H,S
C1976 dollar*. d!977
3,000 acre-ft/yr
20,000 acre-ft/yr
Mot Quantified
90 dBU)
Rot Quantified
Unknown
dollar*. Complete reinjectlon
0.01 Ib/d
21 Ib/d
0.0006 Ib/d
1.100 acre-ft/yr
—
Not Quantified
90 dB(A)
Hot Quantified
HB,
HiS
of geothermal
fluid*.
-12-
-------
8.3 RESOURCE CHARACTERISTICS
Geothermal resources are usually defined as "reserves of
heat relatively near the earth's surface, created by the under-
lying geologic structure of the earth."1 This section discusses
the geology, location, quantity, physical and chemical character-
istics, and ownership of geothermal resources.
8.3.1 Geology
Geothermal energy is derived from the decay of radioactive
elements (chiefly uranium and thorium), friction (tidal and
crustal plate motion), and possibly primeval heat. The heat
is transferred radially outward, mainly by convection with the
ascent of magma in the crust and upper mantle. In the uppermost
part of the crust, convection in deep groundwater transports
heat to the surface. In the crust, most of the earth's heat is
transferred to the surface by conduction through solid rock.2'3'"
The geothermal resource base, defined as the total amount
of heat stored in the outer ten kilometers of the earth, has been
Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy. Prepared
for U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May 1977,
p. 3.
2Jones and Stokes Associates. Geothermal Handbook. Prepared
for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office, June 1976, pp. 3-4.
Department of the Interior. Final Environmental Statement
for the Geothermal Leasing Program.Volume I of IV.Washington,
B.C.:U.S. Government Printing Office, 1973, p. 11-10.
^Resource Planning Associates, Inc., op.cit., p. 33.
-13-
-------
calculated to be 1 x 1021* Btu.1 However, because the heat
is diffuse, only a small fraction of that amount is recoverable.2
Locally, the heat is concentrated in the crust by volcanism,
tectonism, and convection cells of circulating hot waters above
buried magma chambers. The heat is stored in rocks and in
water and steam within pores and fissures.3 These "geothermal
reservoirs" may be defined geologically as hydrothermal con-
vection, hot igneous, and conduction-dominated systems.1*
8.3.1.1 Hydrothermal Convection Systems
Subsurface reservoirs of steam or hot liquid water are
categorized as hydrothermal convection systems. As shown in
Figure 8-2,, a heat source of hot rock or magma that lies
relatively close to the earth's surface (usually at depths of
2 to 8 km) is overlain by a permeable rock formation containing
water. The hot rock or magma transfers heat to the water
circulating in the permeable formation. The water expands
and rises upward as it is heated by the hot rock or magma
below. Above the permeable rock is a layer of impermeable
rock which traps the hot water. If the impermeable layer
contains cracks or fissures through which fluid can rise, the
1White, D. E. and D. L. Williams. "Summary and Conclusions,"
Assessment of Geothermal Resources of the United States - 1975.
Geological Survey Circular 726.Arlington, VA:U.S. Geological
Survey, 1975, p. 147.
2Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy.Prepared
for U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May 1977,
p. 3.
Department of the Interior. Final Environmental Statement
for the Geothermal Leasing Program.Volume I of IV.Washington,
D.C.:U.S. Government Printing Office, 1973, p. 11-10.
"Resource Planning Associates, Inc., op.cit.
-14-
-------
10°C AT
SURFACE
HOT SPRING
OR GEYSER
Figure 8-2. Structure of a Typical Hydrothermal
Convection System
Source: Austin, A. L. (1974, p. 15). As reproduced in:
Western Energy Resources and the Environment: Geo-
thermal Energy?Resource Planning Associates.Fre-
pared for U.S. Environmental Protection Agency, Con-
tract No. 68-01-4100. Washington, D.C.: U.S. En-
vironmental Protection Agency. May 1977.
-15-
-------
hot fluid will emerge as steam (a vapor-dominated system) or
hot liquid water (a liquid-dominated system).1 On the surface,
the hydrothermal reservoir may be manifested as hot springs,
fumaroles, mud pots, or geysers.2
Vapor-dominated fluids are advantageous for power production
because they are usually available at relatively high temperature
and pressure (e.g., 180°C, 114 psia at the Geysers3'1*). Since
the steam contains few particulates or other impurities it can
be used directly to drive conventional steam turbines. Only
three vapor-dominated systems have been identified in the United
States: The Geysers in Sonoma County, California; the Mud
Volcano system in Yellowstone National Park, Wyoming; and a
likely though unconfirmed system in Mt. Lassen National Park,
California. Only the Geysers has been developed commercially.s
Liquid-dominated systems are far more common than vapor-
dominated systems: worldwide, liquid-dominated systems may
be twenty times more common.6 Liquid-dominated systems are
usually classed as:
JResource Planning Associates, Inc. Western Energy Resources
and the Environment^ Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100. Wash-
ington, D.C.: U.S. Environmental Protection Agency, May 1977,
p. 11.
2The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 4.
3Hansen, A. "Thermal Cycles for Geothermal Sites and Turbine
Installation at the Geysers Power Plant, California." Geothermal
Energy, Proceedings of U.N. Conference on New Sources of Energy.
Rome? August 21-51, 1961, pp. 365-379.
"Kruger, P. and C. Otte, eds. Geothermal Energy. Stanford,
CA: Stanford University Press, 1973.
5Resource Planning Associates, Inc., op.cat., p. 15.
6 The Futures Group, op.cit.
-16-
-------
1. High temperature systems, with temperatures
in excess of 150°C;
2. Intermediate temperature systems, with
temperatures ranging from 90°C to 150°C; and
3. Low temperature systems, with temperatures
less than 90°C.1
Only the high temperature system is currently being considered
for electricity generation. Moderate and low temperature systems
are more suitable for direct thermal or other nonelectric
purposes. Nine electricity generating plants have been developed
based on high-temperature hot water systems. Most of these
plants are located in New Zealand, Japan, and Mexico.2 Nonelec-
tric utilizations exist in Iceland, Japan, the Soviet Union,
Hungary, France, Italy and the United States. Hot water plants
at Roosevelt Hot Springs, Utah and Valles Caldera, New Mexico
will be operating by 1982.
8.3.1.2 Hot Igneous Systems
Hot igneous systems include both magma (molten rock) at
temperatures above 650°C and hot dry rocks at temperatures
below 650eC. Magma systems contain more stored heat per unit
volume than other geothermal systems. However, many character-
istics of the magma resource are largely unknown and the
technology required for commercial use of the resource is
Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy"Prepared
for U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May 1977,
p. 16.
2Ibid., pp. 16, 18.
-17-
-------
undeveloped. Large young magma systems are especially attractive
for future exploration and development.1'2
Hot dry rock systems overlie a local heat source such as a
magma chamber. The rock formations in these systems are not
sufficiently permeable to trap water. Consequently, production
requires: 1) creating underground cavities by explosion or
creating large cracks in the rock formation by fracturing with
cold water;3 2) injecting water to absorb the heat from the
rock; and 3) collecting the hot water or steam subsequently
produced. The Los Alamos Scientific Laboratory has successfully
fractured hot rock at Fenton Hill, NM. Eighty-five percent of
the water injected into the formation was recovered at 130°C.
A thermal loop extracting 10 MW of thermal energy is now
operating. "* Commercial utilization of the hot dry rock resource
is not expected until the late 1980's.s
:White, D. E. and D. L. Williams, eds. Assessment of
Geothermal Resources of the United States - 1975.Geological
Survey Circular 726.Arlington, VA:U.S. Geological Survey,
1975, pp. 1-3.
2Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy. Prepared
for U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May 1977.
p. 28.
3 Fracturing is unnecessary if the only deficiency is in
water rather than permeability.
"Mortensen, J. J. "The LASL Hot Dry Rock Geothermal
Energy Development Project." LASL Mini-Review. July 1977.
5LaMori, P. "Geothermal Research and Advanced Technology."
Energy Technology III: Commercialization. R. F. Hill fed.).
Washington,D.C7:Government Institutes, Inc., 1976, p 11".
-18-
-------
8.3.1.3 Conduction-Dominated Systems
Conduction-dominated systems have been described by Resource
Planning Associates:*
Where conduction is dominant, a temperature gradient
exists within the earth such that temperatures
increase proportionally with depth from the surface
at a constant rate. This temperature gradient, or
rate of heat flow, may be increased or decreased by
the presence of fluids or low-conductivity rocks.
The heat content is unrelated to plate tectonics.
Both of the geothermal resources in this category are
conduction-dominated systems, referred to as the
normal gradient and geopressured geothermal reservoirs.
The normal gradient refers to the flow of heat from regional
conductive environments. Given the steady flow of heat, tempera-
tures of 75°C may exist at a depth of about 3 km.2 Heat from
these regional conductive environments is likely to be developed
via the same technology used to recover heat from hot igneous
systems.
Geopressured zones occur throughout the world in basins
where rapid sedimentation and contemporary faulting have
occurred, and are characterized by abnormally high pressures
and temperatures.3 Geopressured reservoirs in the United States
comprise methane-saturated water contained in layers of sand
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May 1977,
p. 33.
2ibid., pp. 33-34.
3Wilson, J. S., et al. Environmental Assessment of Geo-
pressured Waters and Their Projected Uses. Dow Chemical U.S.A.
Prepared for U.S.Environmental Protection Agency, Contract
No. 68-02-1329. April 1977, p. 10.
-19-
-------
and shale beneath impermeable rock. Geopressured waters
containing methane can supply three kinds of energy: thermal,
from the water, which typically has temperatures from 160°C to
200°C; mechanical or hydraulic, from the high pressures present
in the formation; and fuel, from the water, which may contain
a large quantity of methane. In the United States, these geo-
pressured zones occur along the Texas and Louisiana Gulf Coast,
extending out to the Continental Shelf.1 Development is 5 to 15
years in the future.2 Geopressured zones are not known to occur
in the eight western states studied in this report.
8.3.2 Location
Figure 8-3 is a map of known high-temperature U.S. geo-
thermal regions, including the geopressured zone of the Gulf
Coast.3 In the U.S., most locations likely to be developed before
1985 (and probably by 2000) are in the western one-third of the
country. There are currently 441 identified geothermal resource
areas in the U.S.1* Figure 8-4 shows the location of the identi-
fied geothermal resource regions in the eight western states
studied in this report. A known geothermal resource area (KGRA)
Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy. Prepared for
U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 34.
2Wilson, J. S., et al. Environmental Assessment of Geo-
pressured Waters and Their Projected Uses!Dow Chemical U.S.A.
Prepared for U.S. Environmental Protection Agency, Contract No.
68-02-1329. April 1977. p. iv.
3Low-temperature regions not shown in Figure 8-3 (such as
the Madison aquifer) may be used as a source of low grade heat.
"*White, D. E. and D. L. Williams, eds. Assessment of
Geothermal Resources of the United States - 1975.Geological
Survey Circular 726.Arlington, VA:U.S. Geological Survey,
1975, pp. 8-50, 63-77.
-20-
-------
I
I
Hydrothermal Reservoirs
Geopressured Brines
Figure 8-3. Distribution of U.S. Geothermal Resources.
Source: U.S. Department of the Interior. Final Environmental
Statement for the Geothermal Leasing Program, 4 Vols.
Washington:Government Printing Office, 1973.
-------
21
25 -22
• .23
27« "26 .24
Figure 8-4.
The Location of Known Geothermal Resource Areas
in the Eight Western States
-22-
-------
KEY TO FIGURE 8-4
Map
Number
Name-Site
State
Vapor-Dominated (Steam) Systems
Mud Volcano System
Yellowstone National Park Wyoming
High-Temperature Hot-Water Systems (Over 150°C)
2.
3.
4.
5.
6.
7.
8.
Power Ranch Wells
Valles Caldera
Lightning Dock Area
Roosevelt (McKean) H.S.
Cove Fort-Sulphurdale
Thermo H.S.
Yellowstone National Park
Arizona
New Mexico
New Mexico
Utah
Utah
Utah
Wyoming
Intermediate-Temperature Hot-Water Systems (90° to 150°C)
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
Verde H.S.
Castle H.S.
North of Clifton
Clifton H.S.
Eagle Creek Springs
Gillard H.S.
Mt . Graham
Routt H.S.
Steamboat Springs
Idaho Springs
Glenwood Springs
Avalanche Springs
Cottonwood Springs
Mt. Princeton S.
Poncha H.S.
Mineral H.S.
Waunita H.S.
Cebolla H.S.
Orvis H.S.
Wagon Wheel Gap
Pagosa H.S.
Helena (Broadwater) Hot Spring
White Sulphur Springs
Alhambra H.S.
Boulder H.S.
Gregson (Fairmont) H.S.
Pipestone H.S.
Arizona
M
M
M
n
M
Colorado
M
It
II
II
II
II
II
1 1
II
II
II
II
1 1
Montana
"
"
11
1 1
n
-23-
-------
KEY TO FIGURE 8-4 (Continued)
Map
Number
Name-Site
State
36. Barkels (Silver Star) H.S.
37. Norris (Hapgood) H.S.
38. Jardine (Big Hole or Jackson) H.S.
39. Jemez (Ojos Calientes) H.S.
40. Radium H.S.
41. Lower Frisco
42. Gila H.S.
43. Hooper H.S.
44. Crystal H.S.
45. Baker (Abraham, Crater) H.S.
46. Meadow H.S.
47. Monroe (Cooper) H.S.
48. Joseph H.S.
49. Huckleberry H.S.
50. Auburn H.S.
Hot Igneous (Volcanic) Systems
51. San Francisco Mountains
52. Kendrick Peak
53. Sitgreaves Peak
54. Bill Williams Mountain
55. Valles Caldera
56. Mount Taylor
57. No Agua Domes
58. Mineral Mountains
59. Cove Creek Domes
60. White Mountain Rhyolite
61. Tushar Mountains
62. Topaz Mountain
63. Smelter Knoll
64. Yellowstone Caldera System
Montana
New Mexico
n
n
Utah
Wyoming
Arizona
ii
n
New Mexico
Utah
it
M
ii
Wyoming
Source: White, D. E. and D. L. Williams, eds. Assessment of
Geothermal Resources of the United States - 1975.
Geological Survey Circular 726.Washington:
Geological Survey, 1975, pp. 8-5, 53-77.
U.S.
-24-
-------
occurs when "the prospect of extraction of geothermal steam or
associated geothermal resource from an area is good enough to
warrant expenditure of money for that purpose."1 KGRA's also
are designated when applications for non-competitive leases
overlap in an area. As evident from Figure 8-4, there are
currently 64 KGRA's in the study area: 9 in Montana, 5 in
Wyoming, 15 in Utah, 14 in Colorado, 12 in Arizona, and 9 in
New Mexico. There are no KGRA's in North and South Dakota.2
Areas not shown in Figure 8-4 may be sufficient to supply low
grade heat for various non-electric uses.
8.3.3 Quantity
Estimates of the total geothermal energy resource base of
the United States have been reported by Muffler and White3 (1972),
White1* (1973), Rex and Howell5 (1973), and more recently, by
White and Williams6 (1975). These estimates vary widely due to
the uncertain characteristics of the geothermal energy resource.
Godwin, L. H., et al. Classification of Public Lands
Valuable for Geothermal Steam"and Associated Geothermal Resources.
USGS Circular 647.Washington:Government Printing Office,
1971, p. 2.
2White, D. E. and D. L. Williams, eds. Assessment of
Geothermal Resources of the United States - 19T5~! Geological
Survey Circular 726.Arlington, VA:U.S. Geological Survey,
1975.
3Muffler, L. and D. White. Geothermal Energy Resources
of the U.S. U.S. Geological Survey Circular 650. Washington:
Government Printing Office, 1972.
''White, D. E. "Characteristics of Geothermal Resources,"
Geothermal Energy: Resources, Production, Stimulation. P.
Kruger and C. Otte (eds.).Stanford, CA:Stanford University
Press, 1973, pp. 69-94.
5Rex, R. W. and D. J. Howell. "Assessment of U.S. Geothermal
Resources," Geothermal Energy: Resources, Production, Stimula-
tion. P. Kruger and C. Otte (eds.).Stanford, CA:Stanford
University Press, 1973, pp. 59-68.
sWhite, D. E. and D. L. Williams, eds., op.cit.
-25-
-------
The resource assessment presented by White and Williams
relies on data available in 1975, and is subject to revision as
new information becomes available. As defined by White and
Williams, the geothermal resource base includes all stored heat
above 15°C to 10 km depth. Geothermal resources are defined
as "the stored heat, both identified and undiscovered, that
is recoverable using current or near-current technology, regard-
less of cost." The assessment makes no attempt to consider those
legal, environmental, and institutional limitations controlling
the development of geothermal resources.*
Three categories of geothermal resources have been established
by White and Williams: 1) geothermal reserves are those identi-
fied resources recoverable at a cost that is currently competitive
with the costs of other energy resources; 2) paramarginal
geothermal resources are recoverable at costs between one and
two times the current costs of competitive energy systems; and
3) submarginal geothermal resources are those recoverable only
at costs greater than two times the costs of competitive energy.2
Distinctions between these resource categories are dependent on
the prevailing costs of more conventional energy resources. The
distinction between resource base and resources is dependent on
the current state of geothermal technology.
The estimated heat content of the geothermal resource base
of the United States, as summarized by White and Williams, is
reported in Table 8-5. Although the hot igneous and conduction-
dominated systems constitute the greatest portion of the world's
geothermal resource base, White and Williams considered recovery
1White, D. E. and D. L. Williams. "Summary and Conclusions,
Assessment of Geothermal Resources of the United States - 1975.
Geological Survey Circular 726.Arlington, VA:U.S. Geological
Survey, 1975, p. 147.
zlbid.
-26-
-------
TABLE 8-5. ESTIMATED HEAT CONTENT OF GEOTHERMAL
RESOURCE BASE OF THE UNITED STATES3
System Type
llydrothermal Convection
a. Vapor-Dominated
b. High-Temperature Liquid Dominated
c. Intermediate-Temperature Liquid Dominated
TOTAL
Hot Igneous
a. Molten*
b. Hot Rock*
TOTAL
Conduct Ion- Dominated
Identified Systems
Number Heat Content
101* Btu
3 10
63 147
224 137
290 ~29/<
~5200
-4800
-10,000
-3,000,000
Total Resource
Heat Content,
10' s Btu
20
630
560
~1210
-40,000
-3,000,000
3.
ro
I
'lleat In ground, without regard to recoverabllity. Estimates Include all stored heat above 15*C to 10 km depth.
Includes both Identified and estimated undiscovered resource.
cTo 3 km (10,000 ft) depth, near the maximum drilled In geotherm.il areas.
d()vcr 150*0.
€90° to 150*C.
f.;
Molten parts of 48 best known hot Igneous systems, including Alaska and Hawaii.
k
H.
Crystallized parts and hot margins of 48 best known hot Igneous systems
Includes geopressured reservoirs.
Source: White, D. K. and l>. L. Williams. "Summary and Conclusions", Assessment of Ceothermal Resources of the
United States-1975. Geological Survey Circular 726. Arlington, VA: U.S. Geological Survey, 1975 p.148.
-------
technologies for these systems to be relatively undeveloped.1
As discussed earlier, commercial development technologies for
these resource systems may be available by the late 1980*s.
The identified geothermal resource areas of the eight states in
this technology assessment are described in Table 8-6.
Estimates of the near-term development potential of
geothermal resources vary widely, depending on the assumptions
used. One view holds that geothermal energy is most important
for electricity generation, but only in certain local areas
or in undeveloped countries seeking alternatives to even
more expensive energy sources. The counterview holds that
geothermal energy has the greatest potential in non-electric
applications.2
The projections of various studies on the potential of
geothermal energy as a source of electricity are shown in
Table 8-7. Differences among these projections are attributed
to different expectations of future technological breakthroughs,
information on resource characteristics, and future costs of
alternate energy sources.3 The most recent projection of the
commercial utilization of geothermal energy is reproduced in
Table 8-8.
1White, D. E. and D. L. Williams. "Summary and Conclusions,"
Assessment of Geothermal Resources of the United States - 1975.
Geological Survey Circular 726.Arlington, VA:U.S.Geological
Survey, 1975, p. 154.
2Resource Planning Associates, Inc. Western Energy Resources
and^the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100. Wash-
ington, D.C.: U.S. Environmental Protection Agency, May 1977, p. '
3 Ibid. , p. 5.
-28-
-------
TABLE 8-6. IDENTIFIED GEOTHERMAL AREAS OF THE
EIGHT WESTERN STATES
State
Arizona Colorado Montana New Mexico North Dakota South Dakota Utah Wyoming Total
Vapor Dominated Systems
Number of Areas
Assumed Subsurface Area, km2
Assumed Heat Concent, 10 " Btu*
High— Temperature Liquid-Dominated
Systems (over 150 JC)
Number of Areas
Assumed Subsurface Area, km2
Assumed Heat Content, 10" Btu*
Intermediate-temperature Liquid-
Dominate Systems (90"C to 150~C)
Number of Areas
Assumed Subsurface Area, km2
Assumed Heat Content, 10 Btu
Hot Igneous Systems
Number of Areas
Assumed Subsurface Area, km2
Assumed Heat Content, 10uBtua
000
—
100
-2.5
0.1
7 14 9
10.5 27.0 13.5
-0.4 -1.2 -0.6
400
250b
125b -
0 0 00
_
2 0 03
66.5 - - 20.5
-7 -1.5
4 0 06
6.0 - - 12.5
-0.3 - - -0.5
3 0 06
400b - - 104°
160
1
5
-0.3 -0.
1 7
375 465
-53 -62
2 42
3.0 73
-0.2 -3.
1 14
2500 3250
-750 -1035
1
5
3
2
*Heat contents calculated above a base temperature of 15 °C
Data given for one Identified area only.
°Data given for two Identified areas only.
Source: White. D. E. and D. L. Williams), eds. Assessment of
Geothermal Resources of the United Scates-1975.
Geological
Survey Circular 726.
Arlington. VA: U.S. Geological Survey, 1975. pp. 8-72.
-29-
-------
TABLE 8-7. PROJECTIONS OF ELECTRICITY GENERATING CAPACITY
FROM GEOTHERMAL RESOURCES IN THE UNITED STATES,
1985-2000
Projected Capacity, MWe
Source of Projections 1985 2000
Energy Resource Conference, 1975 2,500 to -
5,100
ERDA-86, Geothermal Energy Definition
Report, 1975 6,000 39,000
Electric Power Research Institute, 1976 3,500 10,000
National Electric Reliability Council, 1976 2,080
EKDA, Program Approval Document, 1977 3,000-4,000 20,000-40,000
Sources: Loveland, W. D., B. I. Spinrad, and C. H. Wang, eds. "Magnitude
and Development Schedule of Energy Resources." Proceedings of a
conference held in Portland, July 1975. Oregon State University,
Corvallis, September 1975.
U.S. Energy Research and Development Administration. Definition
Report, Geothermal Energy Research. Development and Demonstration
Program. ERDA-86. Washington D.C., October, 1975.
U.S. Energy Research and Development Administration. Program
Approval Document, Geothermal Energy Development. Fiscal Year 1977,
January 17, 1977
National Electric Reliability Council. "Fossil and Nuclear Fuel
for Electric Utility Generation, Requirements and Constraints
1976-1985." June, 1976.
Resource Planning Associates, Inc. Western Energy Resources and
the Environment: Geothermal Energy. Prepared for U.S. Environ-
mental Protection Agency, Contract No. 68-01-4100. Washington
D.C.: U.S. Environmental Protection Agency, May 1977.
-30-
-------
TABLE 8-8. INTENDED COMMERCIAL DEVELOPMENT OF GEOTHERMAL
ENERGY GIVEN SUCCESSFUL IMPLEMENTATION OF
FEDERAL PROGRAM
1985
2000
2020
Electric Capacity, MWe
3,000-4,000 20,000-40,000 70,000-140,000
Electric Applications -
Equivalent Fossil Fuel
Energy, quads/year
0.2-0.3
1.5-3.0
5-10
Nonelectric Applications,
quads/year
0.1
TOTAL, quads/year
0.3-0.4
2.5-4.0
13-18
15
Note: 1 quad » 10 Btu
Source: U.S. Energy Research and Development Administration. Program
Approval Document, Geothermal Energy Development, Fiscal Year 1977.
January 17, 1977.
-31-
-------
By 1985, electricity generating capacity from geothermal
resources is likely to amount to 2000-4000 MWe.lj2'3 Total U.S.
generating capacity in 1985 has been forecasted as 800,000 MWe.1*
Geothermal electric generating capacity will thus amount to only
0.25 to 0.507o of the total generating capacity in the U.S. By
2000, geothermal electric generating capacity will amount to
10,000-40,000 MWe.5'6 If the total generating capacity in 2000
amounts to about two million MWe7, geothermal electric generating
capacity will comprise 0.50 to 2.07» of the total generating
capacity in the United States.
8.3.4 Physical and Chemical Characteristics
The ranges of concentrations of the various chemicals in
geothermal fluids are shown in Figure 8-5. As evident from
Figure 8-5, concentrations of constituent chemicals in geothermal
National Electric Reliability Council. "Fossil and Nuclear
Fuel for Electric Utility Generation, Requirements and Constraints
1976-1985." June 1976.
2U.S. Energy Research and Development Administration.
Program Approval Document, Geothermal Energy Development, Fiscal
Year 1977. January 17, 1977.p. 3.
3Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May 1977,
p. 3.
"National Electric Reliability Council, op.cit.
5Resource Planning Associates, Inc., op.cit.
6U.S. Energy Research and Development Administration, op.cit.
7The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development7! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury. Connecticut:
The Futures Group, April 15, 1975.
-32-
-------
'
n •
cinomDE
SOOIIIM
CAICIUM
MAOME8IUM
POTASSIUM
ALUMINUM
WON
• KOMDE
M»NQ«HESF
STRONTIUM
• ORON
ZIHC
BARIUM
IIIIHUU
CESIUM
FtuonioE
IE AD
RUBIDIUM
IODINE
COFFER
im F un
AFI8EMC
MCRCURV
CtlROMIUM
ANTIMONY
WCKEl
•I8MUTH
TIN
SILVER
CADMIUM
•ERVllHIM
8ELFNIUM
•UtFATC
IIUCA
AMMONIUM
NITRATE
CO,
Figure 8-5. Ranges of Chemical Constituent Concentrations in Geothermal Fluids, MG/L.
Note: Narrow bars show measured ranges. Wide bars show ranges within which median concentrations will
likely fall.. Where no wide bar is shown, data are insufficient to make judgments as to median
concentrations. Graph prepared by R. P. Hartley, Program Manager for Geothermal Energy, Energy
Systems Environmental Control Division, U.S. EPA, Industrial Environmental Research Laboratory.
Source: Douglas, J. D., R. J. Serne, D. W. Shannon, E. M. Woodruff. Geothermal Water and Gas - Collected
Methods for Sampling and Analysis. BNWL-2094, Battelle-Pacific Northwest Laboratories, August 1976.
Cosner, S. R. Geothermal Brine Data File (Revised). Lawrence Berkeley Laboratory, University of
California. February 3, 1977.
S. K. Sanyal. Preliminary Compilation of Chemical Composition of Geothermal Waters. Geonomics, Inc.
-------
fluids vary widely from site to site. Chief chemical constituents
of geothermal fluids are sodium, calcium, potassium, magnesium,
chloride, sulfate, bicarbonate, and silica. Geothermal steam
at the Geysers has few of these but has significant quantities
of associated gases. Many liquid-dominated systems have fluids
averaging between 2000 and 20,000 ppm total dissolved solids,
principally sodium, calcium, and chloride with varying amounts
of other constituents. Low temperature systems have smaller TDS
concentrations. Lesser but significant amounts of lithium,
boron, fluoride and nitrogen dioxide are also found. At Niland,
in the Imperial Valley in California, total dissolved solids of
250,000 ppm and higher have been reported, principally sodium,
calcium, potassium and chloride. Various heavy metals, such as
iron, manganese, copper, zinc, lead, and strontium have also been
found at Ni-land in concentrations ranging from a few tens to
several hundred ppm, and are likely to be found at other locations.
A few ppm of iron, manganese, aluminum, and arsenic are also
typically present in high-temperature liquid-dominated fields.
Dissolved gases may include oxygen, carbon dioxide, hydrogen
sulfide, methane, hydrogen, ammonia, and nitrogen.1
Because of industrial proprietary information rights,
chemical analyses are generally unavailable for most geothermal
reservoirs in the United States.2 The U.S. Geological Survey
is currently updating and expanding a computerized geothermal
data file (GEOTHERM).3'* An ERDA (Lawrence Berkeley Laboratory)
1Jones and Stokes Associates. Geothermal Handbook. Prepared
for U.S. Fish and Wildlife Service, U.S. Department of the Interior
Contract No. 14-16-0008-968. U.S. Government Printing Office,
June 1976, p. 34.
2
Ibid.
Energy Research and Development Administration. First
. Report, Geothermal Energy Research, Development and
itration Program.—ERDA 77-9, April 1977, p. 20.
''U.S. Geological Survey. Geothermal Fluid Data File.
April 1977.
-34-
-------
program begun in 1976 has been collecting and evaluating fluid
data for resource sites in the U.S. with minimum thermal capa-
cities of 1018 calories. As of November 1976, data had been
collected for 13 of the 33 sites most likely to be developed
by 1985. ERDA has indicated that available geothermal fluid
analyses are not adequate for economic and environmental cost
estimates.l
Characteristics of U.S. geothermal fields at The Geysers
and Niland (in California) are summarized in Table 8-9.
Characteristics of fluids from a well in Sandoval County, New
Mexico, are reported in Table 8-10. Characteristics of liquids
from wells at Roosevelt Hot Springs in Beaver County, Utah, are
summarized in Table 8-11. The characteristics reported in
Tables 8-9 through 8-11 should not be construed as representa-
tive of all geothermal fluids in the U.S. or in the eight
western states.
8.3.5 Ownership
Ownership of geothermal resources has not been well defined,
Because land ownership comprises ownership of surface and
mineral estates (as described in Chapter 2), geothermal fluids
must be defined as minerals or water; water is usually classed
as part of the surface estate. The dispute over ownership of
geothermal resources is still being argued in the courts;2 the
U.S. Supreme Court has ruled that geothermal resources are
minerals for federal purposes.3
Energy Research and Development Administration. First
Annual Report, Geothermal Energy Research, Development and
Demonstration Program.ERDA 77-9, April 1977.pp. 28-29.
2See Section 8.4.4.
3United States v. Union Oil Company of California, 549 F.2d
1271 (1977).
-35-
-------
TABLE 8-9. CHARACTERISTICS OF TWO U.S. GEOTHERMAL FIELDS
Reservoir temperature, °C
Reservoir pressure, psi
Wellhead pressure, psi
Heat content, Btu/lb
Average well depth, ft
Fluid salinity, ppm
Average mass flow per well, Ib/hr
Non-condensable gases, wt.70
Geysers
Vapor
Dominated
245
500
150
1,200
8,200
1,000
150,000
1
Niland
Liquid
Dominated
300+
2,000
400
560
4,250
250,000
440,000
1
Sources: Koenig, J. B. "Worldwide Status of Geothermal Re-
sources Development," Geothermal Energy: Resources,
Production, Stimulation"! P. Kruger and C. Otte, eds.
Stanford, California:Stanford University Press,
1973, pp. 15-58
Austin, A. L., G. H. Higgens, and J. H. Howard. The
Total Flow Concept for Recovery of Energy from
Geothermal Hot Brine Deposits.Lawrence, California:
Lawrence Livermore Laboratory, 1973.
-36-
-------
TABLE 8-10. CHARACTERISTICS OF GEOTHERMAL FLUIDS FROM A WELL
IN SANDOVAL COUNTY, NEW MEXICOa
Characteristics of Steam Phase
Constituent Concentration, ppm
C02 33,700-47,390
H2S 290-567
NH3 1.5-6
CHi» 0-6
H2 1.5-4
N2. 0-109
Characteristics of Liquid Phase
General Properties
pH 6.6-7.1
Conductivity, ymhos/cm 10,630-11,230
Specific gravity 1.008
Constituent Concentration, ppm
Metals
Potassium 463-550
Sodium 2,010-2,200
Calcium 27-46
Si as SiO 640-835
Anions
Bicarbonate 57-128
Carbonate 0
Chloride 3,400-4,400
Sulfide 1.5-6-
Sulfate 50-70
Solids
Suspended solids 522-688
Total dissolved solids 6,896-7,593
Fluid temperature = 170°C. Sampling method: liquid separated from steam
and noncondensable gases in centrifugal separator and cooled under line
pressure. Steam condensed and separated from noncondensables.
Source: U.S. Geological Survey. Geothermal Fluid Data File. April 1977
-37-
-------
TABLE 8-11. CHARACTERISTICS OF LIQUIDS FROM WELLS AT
ROOSEVELT HOT SPRINGS IN BEAVER COUNTY, UTAH
Temperature at bottom bole, °C
pH
Total dissolved solids, ppm
Concentration of chemical
constituents, ppm
S102
Na
K
Li
Ca
Mg
Cl
Br
S0»
Ag
As
B
Co
Cr
Cu
Ma
Mo
Ni
Pb
Zn
F
NOj
HC03
Phillips 54-3B
775
2,400
565
18
9
19
4.800
7
200
0.09
3.5
45
0.15
0.01
0.03
0.15
0.04
0.18
0.1
0.04
Wells
Phillips 54-3A Phillips 9-1
>260°C
6.5
6,442
>560 >170
2,000 2,210
410 425
19 83
10.1
0.24
3,400 2,800
54 122
29
5
Trace
200
Phillips 3-1
>205
6
7,067
560
2,437
448
20
8
0
4,090
59
25
5
0
180
°C
.3
.01
.1
Source: D.S. Geological Survey. Geothermal Fluid Data File. April 1977
-38-
-------
Estimates vary, but about 60 percent of the known geothermal
resources are on land owned by the federal government.1 Owners
of the remainder have not been determined. Table 8-12 reports
the status of geothermal leases on both public and Indian land
in late 1976. Detailed statistics for leases let on private
land are generally not available.
1 Energy "Resource and Development Administration. First
Annual Report, Geothermal Energy Research. Development and
Demonstration Program.ERDA 77-9, April 1977.p. 81.
TABLE 8-12. STATUS OF GEOTHEEMAL LEASES AS OF OCTOBER 31, 1976
Producing
Nonproducing
Total Acreage Under
Supervision to Date
State a No . Acreage
FEDERAL LAND"
Arizona 7 9,594
California
Colorado
Idaho
Montana
Nevada
New Mexico
Oregon
Utah 1 2,463
Wyoming
TOTAL FEDERAL 8 12,057
INDIAN LAND
California
Nevada (Prosp. Permit)
TOTAL INDIAN
Source: U.S. Geological Survey,
No.
4
25
38
78
5
375
65
52
203
2
856
2
2
4
Acreage
6,508
34,297
42,818
128,906
9,407
634,683
139,203
94,735
329,678
2,804
1,423,039
600
291,590
292,190
Conservation Division.
No.
4
32
38
78
5
375
65
61
204
2
964
2
2
4
Monthly
Acreage
6,508
43,891
42,818
128,906
9,407
634,683
139,203
94,735
332,141
2,804
1,435,096
600
291,590
292,190
Geothermal
Report October 1976.
a
North Dakota and South Dakota have no geothermal leases.
rlone of these areas is commercially productive.
-39-
-------
8 - 4 EXPLORATION
In the past, geothermal areas have been located by obvious
surface manifestations such as hot springs, fumaroles, mud pots,
and geysers. There have also been accidental discoveries while
exploring or drilling for other mineral resources.1 More
scientific techniques are required for estimating the location,
depth, volume, temperature, and permeability of heat reservoir
rocks. In the exploration of hydrothermal resources, the
quantity and chemical composition of geothermal fluids must
also be determined.
Exploration techniques in the western United States have
developed from disciplines such as geology, geochemistry, geo-
physics, and hydrology. These exploration techniques vary
according to the area investigated and the investigator's
preferences.2
8.4.1 Technologies
Exploration usually begins with a compilation of available
data from published literature and proprietary sources. This
initial phase usually entails the study of a large region,
perhaps as much as several thousand square kilometers.
Reconnaissance fieldwork follows to obtain geologic and
geochemical data for several closely related prospects tenta-
tively selected in the first phase. The more promising of
:The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 26.
2Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department
of the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976. p. 18.
-40-
-------
these prospects are further investigated in the third phase. In
this phase, more intensive fieldwork is undertaken to better
define geophysical, geologic, and possibly geochemical properties
of the geothermal resource. The fourth and final phase involves
the drilling of deep exploration wells.1
The above sequence for the exploration of geothermal
resources requires the following techniques: geologic and hy-
dro logic surveys, geochemical surveys, geophysical surveys, and
drilling. These techniques are discussed successively in the
following sections.
8.4.1.1 Geologic and Hydrologic Surveys
Geologic and hydrologic surveys are performed to "search
for evidence of tectonic activity and seismic disturbance,
determine the age and distribution of young volcanic rocks,
and locate any surface discharges of steam, water, or warm
mud."2 Data on the temperature and discharge of springs and
wells are collected early in the exploration effort. The
extent and flow of groundwater are also determined. Aerial
photography using visible light, infrared light, and microwave
photographic techniques can be useful in locating geological
faults and unusually warm ground. These techniques are used
for geologic and topographic mapping and structural analysis.
Core samples recovered from shallow exploration wells are used
1 Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department
of the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976. p. 18.
2Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 29.
-41-
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to refine the structural model developed from surface data.1
The objective of these studies is to determine those areas
suitable for more detailed investigation.
8.4.1.2 Geochemical Surveys
Geochemical reconnaissance involves the sampling and
analysis of waters and gases from surface manifestations such
as hot and cold springs and fumaroles. Chloride analyses can
be used to discriminate between liquid- and vapor-dominated
hydrothermal resources. Concentrations of silica and ratios of
sodium.-potassium: calcium can be used to estimate the minimum
reservoir temperature of liquid-dominated hydrothermal systems.
Variations in the chemistry of nearby waters can be used to
evaluate reservoir dimensions and composition.2 Rock age is
determined from solids contained in the water samples.
Geochemical analyses are also performed on core samples
recovered from exploration wells. A temperature profile can
be estimated from ratios of chemical constituents dissolved in
geothermal liquids. Water flow patterns may also be defined
from these chemical analyses. This kind of information can
help to select more promising drilling sites. Geochemistry
can also be used to detect changes in the reservoir during
production, testing, and utilization of the geothermal resource.
1Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department
of the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976. p. 19.
2Ibid., p. 20.
-42-
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Information obtained from geochemical surveys can be used
throughout the life of a geothermal field. Geochemical data
can help to determine the ultimate use of the geothermal resource
and to design the specific processes to be employed at a
particular site. For instance, large quantities of dissolved
solids that would precipitate and obstruct flow during expansion
or temperature decreases might preclude use of certain types of
total flow expanders. Corrosive properties must also be deter-
mined before major pieces of equipment are specified. Geochemical
data thus provide a basis for specifying the end use of a geo-
thermal resource.*
8.4.1.3 Geophysical Surveys
Geophysical surveys are conducted to define specific target
areas for drilling. Electrical and electromagnetic surveys of
deep resistivity can help to define a hydrothermal reservoir,
since hot mineralized fluids are electrically very conductive.
Most exploration programs use direct-current surveys, electro-
magnetic soundings, and sometimes magnetotelluric soundings
of deep resistivity (to depths of eight kilometers). These
techniques are slow and costly, and are performed only during
detailed investigations of particular geothermal targets.2
Passive seismic methods are often used to locate geothermal
reservoirs. These surveys record and locate microearthquakes
and seismic noise, which may be unusually frequent and intense
!The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975.
2Jones and Stokes Associates. Geothermal Handbook. Prepared
for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office, June 1976, p. 19.
-43-
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in geothermal reservoirs. Passive seismic surveys are used
early in the exploration sequence. Active seismic methods are
seldom employed.1
If a prospect remains attractive after the initial phases
of exploration, shallow exploration wells (200-500 feet in
depth) are drilled to measure the temperature gradient. This is
the most direct means of obtaining subsurface temperatures.
Deep reservoir conditions are estimated by projecting these
gradients to greater depth.2
Aeromagnetic and ground magnetic surveys, as well as gravity
surveys, can be useful in defining the subsurface geologic
structure. Such data are usually collected in the early stages
of exploration.3
8.4.1.4 Drilling
The drilling of shallow exploration wells is requisite in
any detailed exploration program. A portable, truck-mounted
rotary drill rig is generally used for this kind of hole. Holes
200 to 300 feet deep are required to obtain measurements undis-
turbed by circulation of shallow groundwater. "*
The final phase of geothermal exploration is the drilling
of deep exploratory wells. Only deep exploratory drilling can
1 Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department
of the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976, p. 19.
zlbid.
3 Ibid.
"ibid., p. 21.
-44-
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determine the true nature of a geothermal prospect in terms of
thermal and chemical character and producible energy. Vital
data to be obtained are temperature and pressure variations
with depth, lithology and stratigraphy, fluid composition (in
hydrothermal or geopressured systems), and rock permeability
and porosity. These data, together with a full set of geo-
physical well-logs and well tests, permit complete evaluation
of the geothermal prospect.l
Geothermal wells for deep exploration are generally drilled
with rotary rigs common to the petroleum and natural gas
industries. The depths required for drilling vary with the geo-
thermal resource. Large volumes of low-enthalpy water suitable
for many direct uses may be found in shallow aquifers at depths
of less than 1000 feet. High-enthalpy hydrothermal resources are
generally found at depths in excess of 2000 feet; many reservoirs
extend deeper than 10,000 feet.2
In rotary drilling, a drilling fluid must be circulated
down through the drill stem to flush out drill cuttings and
protect the hole against collapse. This fluid is usually a dense
mud containing bentonite clay; at temperatures above 150°C,
other compounds must be added to prevent gelling of the mud. Air
has been used as the drilling fluid at The Geysers for the high
temperature region in the vicinity of the reservoir.3 A "mud pit"
is required for storage of the drill mud and waste fluids flushed
up during drilling. Once the drilling reaches the geothermal
1 Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department of
the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976, p. 20.
zlbid., p. 21.
3ibid., p. 22.
-45-
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reservoir, tests are conducted to determine the characteristics
of the geothermal resource.x
8.4.2 Input Requirements
Inputs required for exploration of a geothermal resource
include manpower, materials and equipment, finances, water, land,
and ancillary energy. Each of these requirements is successively
discussed below. Exploration efforts of the past have emphasized
the definition of hydrothermal convection systems. While explor-
ation of igneous and conduction-dominated systems has commenced,
little data on the exploration inputs for these systems have
been reported. Consequently, the following inputs describe the
exploration of hydrothermal convection systems. Exploration
inputs for igneous and conduction-dominated systems can be assumed
to be on the same order of magnitude.
The input requirements and outputs reported below princi-
pally describe an exploration effort designed to locate a hot
water geothermal field with a capacity for the production of 100
MWe electric power for 60-70 years. It is estimated that sixty-
four prospects will be evaluated with geologic and geophysical
techniques. Half of these will require additional geophysical
field work to select twenty-four that justify temperature-hole
programs. From that work sixteen prospects will be selected
for deep exploratory drilling. It is assumed that one of the
sixteen exploratory wells will discover the objective field.
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100. Wash-
ington, D.C.: U.S. Environmental Protection Agency, May 1977,
p. 20.
-46-
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Additional testing with the drilling of three confirmation wells
will complete the exploration effort.1'2
8.4.2.1 Manpower
Manpower requirements for the exploration and appraisal of
a 200 MWe hot water field with a production life of 35 years were
prepared by Bechtel Corporation for the Federal Energy Adminis-
tration. Bechtel's estimates assume an exploration program
essentially similar to the one described above. However,
Bechtel's manpower projections assume the drilling of thirty-two
deep wells; the exploration program defined above assumes the
drilling of sixteen exploratory and three confirmation wells.
Bechtel's manpower projections are scaled to the drilling efforts
assumed in this analysis. These manpower estimates are summarized
in Table 8-13. The data assume that sixty calendar days are
required to drill each deep well. Two drilling rigs are required
for eighteen months .3 ' "*
8.4.2.2 Materials and Equipment
The materials and equipment required for geologic, geother-
mal, and geophysical techniques are standard, and include such
1B. Grieder. "Status of Economics and Financing of Geother-
mal Energy Power Production." Proceedings Second United Nations
Symposium on the Development apcF Use of Geothermal Resources"!
San Francisco, CA, May 20-29, 1975.Washington, B.C.:U.S.
Government Printing Office, 1976, pp. 2305-2314.
2Greider has described the exploration effort to discover
a 200 MWe field; a field of 100 MWe will require the same effort
if the intended development life of the 100 MWe field is twice
that of the 200 MWe field.
^B. Grieder, op.cit.
^Federal Energy Administration. Interagency Task Force on
Geothermal Energy. Project Independence Blueprint Final Task
Force Report: Geothermal Energy. Washington, D.C. : U. S.
Government Printing Office, 1974, pp. D-3, D-4.
-47-
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TABLE 8-13. MANPOWER REQUIREMENTS FOR EXPLORATION
AND APPRAISAL OF A HOT WATER FIELD WITH
A CAPACITY FOR THE PRODUCTION OF 100 MWe
ELECTRIC POWER
Skill
Geologist
Geophysicist
Landman
Drill rig foreman
Drillers
Laborers
Truck drivers
Geo chemists
TOTAL
Man-years
First Year Second Year
3
2
2
1
3
2
1
1
15
3
2
1
2
6
4
2
1
21
Sources: Federal Energy Administration. Interagency Task Force
on Geothermal Energy. Project Independence Blueprint
Final Task Force Report: Geothermal Energy. Washing-
ton, D.C.: U.S. Government Printing Office, 1974.
pp. D-3, D-4.
B. Greider. "Status of Economics and Financing of
Geothermal Energy Power Production." Proceedings
Second United Nations Symposium on the Development and
Use of Geothermal Resources.San Francisco, CA,
May 20-29, 1975.Washington, D.C.: U.S. Government
Printing Office. 1976. pp. 2305-2314.
-48-
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items as office space and supplies, maps, access to a properly
stocked library and well log file, drafting and mapmaking facil-
ities, and materials for report writing. For the fieldwork and
drilling segments of the exploration program, field vehicles and
equipment are also required.
In most cases, materials and equipment for drilling will
not be provided by those conducting the exploration, but will
be provided by a contractor who is commissioned for the drilling.
This equipment includes such items as a drill rig, water truck
and/or air compressor, mud pumps and handling equipment, drill
pipe and bits, and core barrel (if applicable). Facilities and
equipment must also be provided for the well-site geochemist,
including a logging trailer, and samples description and collec-
tion material. Borehole geophysical equipment, including a logging
truck and appropriate sondes (probes) are usually provided by a
contractor specializing in well logging.
8.4.2.3 Economics
Greider1 has estimated the cost of an exploration program
proving a liquid-dominated system with a capacity for the pro-
duction of 200 MWe electric power. Greiderfs cost estimate is
presented in Table 8-14. The cost of exploration will vary
with location, geothermal field characteristics, and type of
planned development. The costs in Table 8-14 also describe
a 100 MWe field with a production life twice that of the 200
MWe field.
Greider, B. "Status of Economics and Financing of Geother-
mal Energy Power Product-ion." Proceedings Second United Nations'
Symposium on the Development and Use of Geothermal Resources^
San Francisco, CA, May 20-29, 1975. Washington, D.C.: Government
Printing Office, 1976, pp. 2305-2314.
-49-
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TABLE 8-14. EXPLORATION COSTS TO PROVE A HOT WATER FIELD CAPABLE
OF THE PRODUCTION OF 200 MWe ELECTRIC POWER
Activity Costa
Initial geology and geophysics $ 2,560,000
Additional geophysics0 480,000
Temperature hole programs 960,000
Land acquisition6 1,680,000
Deep drilling
12 Failures 4,380,000
3 Failures with casing run 1,350,000
1 Discovery plus 3 confirmation 1,505,000
Well testing8 540,000
TOTAL $13,455,000
aCost in 1975 dollars.
Based on investigation of 64 areas.
°Based on investigation of 32 areas.
Based on investigation of 24 areas.
eAssumes acquisition of 7500 acres for each of 32 areas at a
cost of $7.00/acre.
fDrilling to a depth of 5000 feet.
sThese tests are used to establish the commercial potential
of the geothermal resource.
Source: Greider, B. "Status of Economics and Financing of Geo-
thermal Energy Power Production." Proceedings Second
United Stations' Symposium on the Development and Use
of Geothermal Resources"San Francisco, CA.May 20-29,
1975.Washington:Government Printing Office. 1976.
pp. 2305-2314.
-50-
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Another estimate of the cost of exploration is reported
in Table 8-15. Barr's1 estimate describes an exploration pro-
gram to discover one dry steam field. Barr's analysis assumes
an initial evaluation on only thirty geothermal prospects, with
the drilling of only four deep wells.
8.4.2,4 Water
Water requirements for the application of geologic, geo-
chemical, and geophysical techniques are very small. Water
requirements during drilling amount to 200-500 barrels per rig-
day, primarily for use as drilling fluid. Using the average
consumption of 375 barrels per rig-day2 and assuming that sixty
days are required to drill each well, the average water require-
ment is calculated to be 22,500 barrels per well. Water
requirements for the drilling of 19 wells thus amount to about
55 acre-feet.
8.4.2.5 Land
During the initial stages of exploration, small land areas
are disturbed by surface surveying. Somewhat greater disturbances
occur during geochemical and geophysical surveys. Even the
drilling of shallow temperature gradient wells is confined and
'Barr, R. C. "Geothermal Exploration: Strategy and Budget-
ing. " Proceedings Second United Nations' Symposium on the Devel-
opment and Use of Geothermal Resources.San Francisco, California,
May 20-29, 1975.Washington, B.C.:Government Printing Office,
1976, pp. 2269-2271.
2Federal Power Commission. National Gas Survey, Volume II.
Washington, B.C.: U.S. Government Printing Office,1973, p. 74.
-51-
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I
tn
to
i
TABLE 8-15. EXPLORATION COSTS FOR A THREE-YEAR EXPLORATION PROGRAM DEFINING
A FIELD SUFFICIENT FOR A 200 MWe POWER GENERATING FACILITY3
Function
Management expense
Target selection/evaluation
Land acquisition/rentals
Detailed geophysics
Site selection
Deep drilling
Cont ingencies
TOTAL
aCosts in 1975 Dollars.
First Second
Year Year
$ 175,000 $ 175,000
150,000
775,000 475,000
325,000 650,000
100,000
500,000
150,000 200,000
$1,575,000 $2,100,000
Source: Barr, R.C., "Geothermal Exploration: Strategy and
Third
Year
$ 175,000
—
125,000
—
300,000
1,500,000
225,000
$2,325,000
Total
$ 525,000
150,000
1,375,000
975,000
400,000
2,000,000
575,000
$6,000,000
Budgeting." Proceedings Second
United Nation's Symposium on the Development and Use of Geothermal
Resources .
San Francisco, California, May 20-29, 1975. Washington: Government Printing Office.
1976. pp. 2269-2271.
-------
short-lived.1 However, significant disturbances occur during
deep exploratory drilling.
A typical well-drilling operation disturbs about one acre
of land from clearings, roads, mud pits and the like. Efficient
operators may disturb only one-half acre, but one acre is typical.
The drilling of 19 wells will thus temporarily disturb about 19
acres of land. Once drilling operations have ended, only a small
residual amount of land is committed to the completed well. The
disturbed land can then be restored to its natural state. The
well-head itself consumes only a small fraction of an acre per
well.2
8.4.2.6 Ancillary Energy
Small quantities of fuel for field vehicles are required
during fieldwork. Larger quantities of fuel are used for
operating drill rigs during the drilling program.
Fuel requirements for drilling vary with rig size, type of
rock formation drilled, and well depth. The Federal Power Com-
mission has indicated that 900-1800 gallons of diesel fuel are
consumed per rig-day.3 Assuming a fuel consumption of 1500
gallons per rig-day and a drilling time of sixty days, it is
estimated that 90,000 gallons of diesel fuel are required for
1 Jones and Stokes Associates. Geothermal Handbook. Pre-
pared for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office. June 1976.
2Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California: "Water.
and Land Use Issues. Working Paper No. 2, Jet Propulsion Labora-
tory, California Institute of Technology, December 14, 1976. .
3Federal Power Commission. National Gas Survey, Volume II.
Washington, D.C.: U.S. Government Printing Office, 1973, p. 74.
-53-
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drilling one well. The drilling of nineteen wells consumes
about 1,700,000 gallons of diesel fuel.
8.4.3 Outputs
Outputs produced during the exploration of geothennal
resources are discussed in the following sections. These outputs
include air emissions, water effluents, solid wastes, noise
pollution, occupational health and safety hazards, and odor.
8.4.3.1 Air Emissions
' Some air pollutants are generated by field vehicles during
exploration, but the quantities are small. Sources of air
emissions during drilling include: exhaust from diesel generators;
dust and exhaust from vehicles traveling on access roads; and
»f
exhaust of gases contained in the geothermal fluids and uncontrolled
blowouts. The most important of these emission sources are dis-
cussed below.
During exploratory drilling, potentially the largest source
of air pollutants is exhaust from diesel generators. Emissions
from this source are summarized in Table 8-16. These estimates
are based on the diesel fuel requirement and emission factors
published by the Environmental Protection Agency.l Carbon
dioxide emissions are estimated from the carbon content of
diesel fuel.
'U.S. Environmental Protection Agency. Compilation of Air
Pollutant Emission Factors. Second Edition, Third Printing with
Supplements 1-5. Research Triangle Park, North Carolina:
February 1976, pp. 3.3.1-1, 3.3.3-2.
-54-
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TABLE 8-16. AIR EMISSIONS DURING EXPLORATORY DRILLING*
Source
Constituent
Quantity
Diesel Generators
Carbon monoxide
Hydrocarbons
Nitrogen oxides
Aldehydes
Sulfur oxides
Particulates
Carbon dioxide
87 tons
32 tons
401 tons
6 tons
27 tons
29 tons
18,400 tons
Geothermal Fluids'
Steam
Carbon dioxide
Ammonia
Methane
Hydrogen sulfide
Nitrogen and argon
Hydrogen
355,000 tons
2,800 tons
250 tons
180 tons
180 tons
110 tons
35 tons
aThe shown values are total emissions during exploratory drilling
The emissions occur evenly over eighteen months.
bBased on diesel fuel requirement and EPA emission factors.
°Based on emissions at The Geysers.
Source: U.S. Environmental Protection Agency. Compilation of
Air Pollutant Emission Factors. Second Edition, Third
Printing with Supplements 1-5. Research Triangle Park,
North Carolina. February 1976. pp. 3.3.1-1, 3.3.3-2.
Teknekron, Inc. "Fuel Cycles for Electric Power Genera-
tion." Comprehensive Standards: The Power Generation
Case. EPA No. 68-01-05bI.Washington, D.C.:U.S.
Environmental Protection Agency, 1975.
-55-
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Exploratory wells intercepting geothermal fluids are poten-
tial emission sources of gaseous substances dissolved in a liquid
resource or contained in steam. This emission source is discussed
extensively in Section 8.5.3.1. For this analysis, only the dis-
covery and confirmation wells are assumed to be sources of these
gaseous contaminants. Total emissions from these four wells are
shown in Table 8-16, as extrapolated from data in Table 8-29.l
The emissions are based on operations at The Geysers. The Geysers
are generally considered to have "cleaner" steam than most other
geothermal resources. For comparable levels of power production
capacity, emissions from many hot water systems are likely to
be comparable to or greater than the emissions at The Geysers.2
Uncontrolled blowouts occur infrequently, but can be a sig-
nificant source of air pollution. This source is discussed in
Section 8.5.3.1.
8.4.3.2 Water Effluents
Drilling mud and geothermal fluids are the major liquid ef-
fluents from well drilling. Muds used in well drilling may contain
certain toxic additives. The muds are also usually very basic
(pH up to 10) from the addition of sodium hydroxide.3 A typical
drilling mud is 95% water. * Based on the water requirement for
^eknekron, Inc. "Fuel Cycles for Electric Power Generation."
Comprehensive Standards: The Power Generation Case. EPA No. 68-01-
0561.Washington, D.C.:U.S. Environmental Protection Agency, 1975
2Resource Planning Associates, Inc. Western Energy Resources
and the Environment; Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May 1977.
3Jones and Stokes Associates. Geothermal Handbook. Pre-
pared for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office. June 1976. p. 146.
"Campbell, M. D. and J. H. Lehr. Water Well Technology.
New York: McGraw-Hill Book Company, 1974, p. 585.
-56-
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drilling (see Section 8.4.2.4), approximately 58 acre-feet of mud
are used in the drilling of 19 wells. During drilling at The
Geysers, sumps with impervious linings or steel tanks are used to
contain this liquid effluent and thus prevent the contamination
of surface waters. Ground-water supplies are protected from con-
tamination only when the well is cased. * After drilling, the
water is evaporated from the sump which can then be landfilled.
Geothermal fluids are brought to the surface during drilling
and well testing. Jones and Stokes Associates have reported that
as much as 34,100 cubic meters (approximately 28 acre-feet) of
liquid from a liquid-dominated geothermal field may be discharged
at the surface from each producing well. In this analysis, only
the discovery and confirmation wells are assumed to discharge
geothermal fluids. The maximum quantity of geothermal fluids
assumed to discharged from these four wells is 112 acre-feet
during the eighteen-month exploration program. The fluid may be
stored on site in the mud sumps or discharged into the surface
drainage system if a National Pollutant Discharge Elimination
System (NPDES) permit has been obtained (see Chapter 2 for details).2
Some sample characterizations of these geothermal fluids have been
reported in Section 8.3.4.
Additional contamination of surface and subsurface waters
may occur from well blowouts. These infrequent events are dis-
cussed in Section 8.5.3.2.
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, pp. 54-56.
2Jones and Stokes Associates. Geothermal Handbook. Pre-
pared for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office. June 1976. p. 155.
-57-
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8.4.3.3 Solid Wastes
The only solid wastes generated during exploration are
drill cuttings. Between 0.8 and 1.6 cubic meters of drill cut-
tings are left on site from each shallow temperature gradient
well.1 For each 5000-foot exploratory well, the volume of drill
cuttings amounts to about 0.1 acre-feet. Nineteen deep explora-
tory wells produce about two acre-feet of drill cuttings. These
wastes are typically disposed in mud sumps. After water has
evaporated, the sumps are land-filled.
8.4.3.4 Noise Pollution
Noise sources during exploration include: field vehicles,
diesel generators, air compressors, and vented gases. The
highest noise levels are associated with deep exploratory
drilling. Noise levels during drilling are shown in Table 8-17.
8.4.3.5 Occupational Health and Safety Hazards
During fieldwork, personnel are exposed to some very minor
hazards such as falls or heat prostration. Drilling operations
pose greater but nevertheless minor hazards to crew personnel.
Worker exposure to toxic gases is also a hazard and is discussed
in Section 8.5.3.5.
8.4.3.6 Odor
Odors during exploration are chiefly associated with the
presence of ammonia and hydrogen sulfide. These odors originate
1 Jones and Stokes Associates. Geothermal Handbook. Pre-
pared for U.S. Fish and Wildlife Service, U.S. Department of
the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office. June 1976. p. 155.
-58-
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TABLE 8-17. NOISE LEVELS DURING THE EXPLORATORY DRILLING
OF GEOTHERMAL RESOURCES
Operation Duration Noise Level Distance
dB(A) Ft.
Mud drilling
Air drilling, including
blow line
blow line with air sampler
blow line with air sampler
and water injection
Well cleaning, open well
Well testing, open well
Rock muffler
60 days /well
30 days /well
3-6 days
14 days
75-80
120
95
85
118
118
89
50
25
25
25
50
50
50
Source: Ecoview Environmental Consultants. Draft jinvironmental Impact
Report for Geothermal Development of Union Oil Company's Lease-
holds on the Upper Part of the Squaw Creek Drainage at the
Geysers, Sonoma County, California Napa, California, 1974.
Reed, M. J. and G. E. Campbell, "Environmental Impact of Develop-
ment in the Geysers Geothermal Field, U.S.A.", Proceedings of
the Second United Nations Conference on the Development and Use
of Geothermal Resources, San Francisco, CA, May 20-29, 1975.
Washington Government Printing Office, 1976.
-59-
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mainly from geothermal fluids brought to the surface in drilling
mud and during well testing. Hydrogen sulfide has a choking
odor similar to that of rotten eggs. Its presence can be detected
in concentrations as low as . 025 ppm. * Ammonia has a character-
istic pungent odor. Holding effluents in enclosed tanks will help
to control odors but no totally effective control is available.
Other odorous air pollutants encountered during drilling are sulfur
dioxide and nitrogen dioxide, which are emitted principally from
diesel equipment.
The inputs and outputs of geothermal exploration are sum-
marized in Table 8-18.
8.4.4 Exploration Social Controls
Exploration and development of geothermal resources is con-
trolled by the owner of the resource, but there is still debate
about whether geothermal energy constitutes a water resource
(owned by the surface land owner) or a mineral resource (such
as oil or gas and owned by the holder of mineral rights).2 In
addition, geothermal energy in hot dry rock is neither an ex-
tractable mineral or a fluid, and hence may be subject to dif-
ferent laws altogether.
Therefore, prior to any discussion of jurisdiction over the
exploration and development of the geothermal resource, resource
ownership must be established. This problem of resource
Department of the Interior. Final Environmental Statement
for the Geothermal Leasine Program. Volume I of IV. Washington,
D.C.: U.S. Government Printing Office, 1973.
2This debate may still exist concerning state or privately
owned geothermal resources, but the 9th Circuit Court has held
that geothermal energy constituted a mineral resource in its
review of U.S. v. Union Oil Co. 549 F.2d 1271 (1977).
-60-
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TABLE 8-18. SUMMARY OF INPUTS AND OUTPUTS OF AN EXPLORATION
EFFORT INTENDED TO DISCOVER A FIELD SUFFICIENT
TO PRODUCE 100 MWe ELECTRIC POWER
Input Requirements
Manpower
• first year
• second year
Materials and equipment
Economics
Water
Land
• temporary
• permanent
Ancillary energy
15 man-years
21 man-years
Not quantified
$13 million3
55 acre-feet
19 acres
less than 1 acre
1,700,000 gal. diesel fuel
Outputs
Air emissions
• steam
• carbon dioxide
• carbon monoxide
• hydrocarbons
• nitrogen oxides
• aldehydes
• sulfur oxides
• particulates
• ammonia
• hydrogen sulfide
• nitrogen and argon
• hydrogen
355,000 tons
21,000 tons
87 tons
210 tons
400 tons
6 tons
27 tons
greater than 29 tons
250 tons
180 tons
110 tons
35 tons
11975 dollars.
Over 18 months.
(Continued)
-61-
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TABLE 8-18.
SUMMARY OF INPUTS AND OUTPUTS OF AN EXPLORATION
EFFORT INTENDED TO DISCOVER A FIELD SUFFICIENT
TO PRODUCE 100 MWe ELECTRIC POWER (Continued)
Water effluents
• drilling mud
• geothermal fluids
Solid wastes
• drill cuttings
Noise pollution
• well cleaning
Occupational health and safety
Odors
58 acre-feet
112 acre-feet
2 acre-feet
118 db(A)c
data unavailable
H2S
NH3
'50 ft. distance.
-62-
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ownership as applied to resource regulation will occur repeatedly
throughout this chapter.
Table 8-19 illustrates both the difficulty in classifying
geothermal energy and the widely ranging solutions used by the
states. Note that the western states are mainly found in the
group not classifying the geothermal resources.
The Union Oil decision is consistent with that of another
court in Geothermal Kinetics vs. Union Oil. The court noted
that the water in geothermal resource development is valuable
not for water in its normal context, but rather only as a conduit
for the energy it gains when in contact with the molten minerals
and gases within the resource. The court therefore held that the
geothermal resource was owned by the mineral owner.l
An additional problem concerning ownership of geothermal
resources is its connection to water laws. This is of most
importance on federal lands where, by an executive withdrawal
of hot springs type waters from public lands in 1930, the
Department of Interior suggests that state laws do not apply to
those reserved waters.2
Geothermal Kinetics, Inc. v. Union Oil Company, No. 75314
(Super. Ct., Sonoma County, CA, Filed June 1, 1976). Another
case is presently in a different California court testing whether
a reservation of "all minerals" by the State of California in-
cluded geothermal resources. See Pariani et al v. State of
California, No. 657-291 (Super. Ct., San Francisco County;.
2Kitchen, Gerald J. "Geothermal Leasing Practices."
Geothermal Resources Development Institute. Boulder, Colorado:
Rocky Mountain Mineral Law Foundation, 1977, p. 3-14.
-63-
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TABLE 8-19. CLASSIFICATION OF GEOTHERMAL RESOURCES
Those Not Not Classified
Classifying Classifying Classifying as Mineral
Geothermala It Mineral It Water or Water
Federal , Hawaii Wyoming Idaho
Colorado" Nevada" Montana
Arizona Washington
Alaska
New Mexico
Louisiana
California
Texas
Nevada0
Utah
aSouth Dakota and North Dakota have no geothennal legislation.
Colorado calls geothennal "not a mineral."
cNevada-at first classified geothermal as water, but recently
has adopted a non-classification with regulations soon to be
promulgated.
Source: Sacarto, Douglas M. State Policies for Geothermal
Development. Denver: National Council of State
Legislatures, November 1976, p. 44.
-64-
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8.4.4.1 Exploration Permits on Federal Lands
The Geothermal Steam Act of 1970l contains no provisions
with respect to granting of exploration rights. However, in
accordance with his rule-making authority, the Secretary of
Interior has established procedures for undertaking exploratory
activities.2
Any person desiring to explore for geothermal resources on
federal lands must obtain an exploration permit from BLM, whether
the exploration is prior to or after the issuance of a lease.
Application, entitled "Notice of Intent and Permit to Conduct
Exploration Operations (Geothermal Resources)" is made to the
district BLM office. This "Notice of Intent" must describe the
lands to be explored by township, briefly describe the proposed
plan of operation, and estimate the dates of commencement and
termination of exploration activities. Simultaneously with the
filing, and before the developer enters the land, a bond of not
less than $5,000 must be submitted to BLM.3 The USGS must give
administrative approval to the plan for exploration. The
explorer may not drill deeper than 500 feet, and the BLM also
has broad discretionary authority to establish terms and con-
ditions under which exploration may take place, particularly
whether additional measures will be taken to insure that any
damaged land will be rehabilitated. BLM may suspend or terminate
exploration operations at any time the agency determines there
is non-compliance with the terms and conditions of the "Notice
of Intent."
13Q U.S.C. §§1001-1025 (1970).
243 C.F.R. §3209.
343 C.F.R. §3209.4-1.
-65-
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Geothermal exploration permits granted prior to a lease do
not give the holder an exclusive right to prospect for resources
on the land described in the "Notice of Intent" or any preference
•
rights to geothermal resources or any lease.1 Upon completion of
the exploration, the developer must file with BLM a "Notice of
Completion of Exploration Operations." Within 90 days thereafter,
the agency notifies the person or corporation who had conducted
the exploration whether the terms of the permit have been suffi-
ciently met or whether additional measures need to be taken to
rectify any damage to the land. Core drilling or development
wells are not allowed under this permit but require that a lease
be obtained first.
8.4.4.2 Exploration Permits on State Lands
Six of the eight western states, Wyoming, Arizona, New Mexico,
Utah, Montana, and Colorado have adopted geothermal laws. In
some cases prospecting permits, though not provided for in state
law, may be issued within the discretion of the state leasing
agency. Wyoming alone requires a permit by statute.
The term for Wyoming's prospecting permit is three years
and may be renewed for two years. Wyoming issues prospecting
permits on newly offered land by public drawing, whereas lands
previously opened are available for prospecting permits upon
application. The permit holder is given the right to convert
his permit into lease if the land is reclassified as a Known
Geothermal Resource Area (KGRA).
143 C.F.R. §3209.0-2.
-66-
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The remaining five1 states in the West allow exploration
of Non-KGRA lands by issuance of lease. For areas already
classified as having geothermal potential, exploration is only
permitted on leased land by lease holders. Colorado has provided
little statutory authority and gives its state land commissioners
the power to specify the leasing provisions. Table 8-20 sum-
marizes the state provisions for exploration of state lands.
TABLE 8-20.
EXPLORATION OF STATE LANDS FOR GEOTHERMAL
RESOURCES FOR NON-KGRA LANDSa
Newly Offered
Application Overlap'5
Arizona
Colorado
Montana
New Mexico
Utah
Wyoming
By application
Determined by Agency
Competitive
Competitive
By application0
Public drawing
Qualifications or
Cash Bonus Bidding
Determined by Agency
Competitive
By application
By application
aSouth Dakota and North Dakota have no provisions for exploration,
In cases where there is an overlap of applied for lease areas,
the administering agency will give priority to applicant by the
method listed.
cUtah offers newly opened lands for cash bonus bidding only.
Source: Sacarto, Douglas M. State Policies for Geothermal
Development. Denver:National Council of State
Legislatures, November 1976, p. 48.
1 Since North Dakota and South Dakota have limited geo-
thermal potential and have no laws, the five states are Arizona,
Montana, Colorado, Utah, and New Mexico.
-67-
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8.5 EXTRACTION: DRILLING
As shown in Figure 8-1, the extraction of geothermal energy
comprises two phases: drilling and production. This section
describes only the drilling operation. Facilities required to
control and transport the geothermal fluid to its point of
utilization are discussed in Section 8.6, Extraction: Production,
8.5.1 Technologies
Geothermal production wells are usually drilled with rotary
rigs common to the petroleum and natural gas industries. Several
novel drilling methods are being researched to increase the
drilling rate, reduce costs, and increase the ultimate depth
attainable. Both the rotary and novel drilling methods employ
one or a combination of four mechanisms for excavating rock.
These include mechanically induced stresses, thermally induced
stresses, fusion and vaporization, and chemical reactions.1
Mechanically induced stresses are produced by standard
rotary drills, explosive drills, and ultrasonic drills. These
drills induce mechanical stresses by impact, abrasion, or
erosion. Brittle fracturing occurs when these stresses exceed
the tensile or shear strength of the rock.2
Thermally induced stresses are produced by forced-flame
drills, microwave drills, induction drills, and others. These
^laurer, W. C. Novel Drilling Techniques. Elmsford, New
York: Pergamon Press, 1969.
2The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development^Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 30.
-68-
-------
drills generate thermal stresses that fracture rock by inducing
thermal expansion.l
Rocks may be fused or vaporized by introducing heat at a
rate sufficient to produce local temperatures greater than the
melting or vaporization temperatures of the rock. This principle
is employed by electric heater drills, electron beam drills, and
laser drills.*
Chemical drills use highly reactive chemicals to dissolve
rock. Chemicals may also be used to alter rock hardness in order
to increase the drilling rate of standard drills.3
In standard rotary drilling, a drilling fluid is circulated
to cool the drill bit and remove rock cuttings from the bore
hole. The drilling fluid is usually a dense mud containing ben-
tonite clay and water; at temperatures above 150°C, additives
are required to prevent gelling of the mud.1* Drilling mud deter-
iorates rapidly at temperatures above 177°C, slowing the circu-
lation of cuttings being removed. High-temperature drilling
fluids are still under development.! A cooling tower may be
required to cool drilling mud.
xThe Futures Group. A Technology Assessment of Geothermal
Energy Resource Developments Prepared for National Science
Foundation, Contract No, C^"836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 30.
2jJbid.
"•Jones and Stokes Associates. Geothermal Handbook. Prepared
for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office, June 1976, p. 22.
5Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 31.
-69-
-------
Air is also used as drilling fluid.1 Advantages of air
drilling are:
higher drilling speeds and lower drilling costs
less damage to production zone from clogging
by circulating mud
no requirements for storage of drilling mud.
Air drilling is not suitable for those formations bearing much
water or having strong sloughing tendencies. Air drilling may
be unable to provide sufficient cooling to the drill bit.2
Typically, mud drilling is employed when drilling through water-
bearing formations. Air drilling may then be used to drill
through the deeper formations containing no water. A typical
well configuration at The Geysers is shown in Figure 8-6.
Rock formations in geothennal areas are generally fractured
and faulted, causing frequent losses of drilling fluid. Thus,
drilling will proceed more slowly than the drilling for natural
gas or petroleum.3 The hard abrasive rock surrourding geothennal
resources is difficult to penetrate even with tungsten carbide
JThe Futures Group. A Technology Assessment of Geothennal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No.0^836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 31.
2Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department
of the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976, p. 22.
3Ibid.
-70-
-------
t
This Interval
Drilled With
Mud
This Interval Drilled
With Mud Or Air
(Depending On
Formation)
This Interval
Drilled With Air
'"300 Ft., 20 In.
2000 Ft., 13 In.
Top Of Probable
Steam Zone
4000 Ft, 10 In.
— Steam Entries
Open Hole, 9 In.
Figure 8-6. Typical Well Configuration at the Geysers.
Source: Budd, C. F. , Jr. "Steam Production at the Gey-
sers Geothermal Field," Geothermal Energy: Re-
sources, roduction. Stimulation. P. Kruger and
Stanford, California: Stanford
C. TDtte,
University Press, 1973.
-71-
-------
bits. The hard rock slows drilling and increases the wear of
bits, causing more frequent replacement.1
Wells may be drilled directionally, in order to reach a
desired subsurface position not directly beneath the drilling
site. This may be necessitated by limited surface access for
vertical drilling. Vertical drilling is far less expensive and
is more commonly employed. The maximum practical horizontal
reach of a well is probably less than 5000 feet.2'3
Geothermal wells are cased above the producing zone for four
reasons:
1) to prevent undesirable fluids of low enthalpy
or high acidity from entering the well;
2) to prevent the sloughing or erosion of particles
above the production zone that could damage
piping, valves, and turbines;
3) to prevent contamination of ground water; and
4) to provide an anchor for a blowout preventer.1*
1 Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S. Envi-
ronmental Protection Agency, Contract No. 68-01-4100. Washington,
D.C.: U.S. Environmental Protection Agency, May 1977, p. 31.
2Jones and Stokes Associates. Geothermal Handbook. Prepared
for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office, June 1976, p. 22.
3The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Frepared for National Science
Foundation, Contract No. C-836. Glastonburyj Connecticut: The
Futures Group, April 15, 1975, p. 31.
*Jones and Stokes Associates, op.cat., p. 31.
-72-
-------
The production zone may be bare (no casing), have a
slotted liner, or a solid liner perforated after setting in
place. The casing is cemented to the formation to prevent
vibration, to insure that geothermal fluids do not erupt in the
annulus between the casing and the drill hole, and to prevent
the casing from being ejected from the drill hole. Special
high-temperature cements and in special cases acid-resistant
cements are used and being developed.1
The extraction of geothermal fluids from the geopressured
zones of the Gulf Coast requires wells drilled to 12,000-15,000
feet. Large volumes of low-enthalpy water suitable for many
non-electric uses are found in shallow aquifers at depths of
less than 1000 feet. High-enthalpy hydrothermal resources are
generally found at depths in excess of 2000 feet; many reservoirs
extend deeper than 10,000 feet.2 Completed wells at The Geysers
range from 600 to 9000 feet. To date, no geothermal wells
have been drilled beyond 10,000 feet.
The spacing of production wells has been described by Jones
and Stokes Associates:3
Wells should be spaced close enough to maximize the
rate of production from a given field, or portion of
a field, and far enough apart so as not to interfere
with each other. Wells are said to interfere when
production from one well reduces production from a
neighboring well. Optimum spacing is governed by the
:The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut:
The Futures Group, April 15^1975, p. 31.
2Jones and Stokes Associates. Geothermal Handbook. Prepared
for U.S. Fish and Wildlife Service, U.S. Department of the
Interior, Contract No. 14-16-0008-968. U.S. Government Printing
Office, June 1976, p. 21
3ibid., pp. 25, 28.
-73-
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porosity and permeability of the reservoir rocks,
and these may be expected to vary widely. At The
Geysers, optimum well spacing has been found to
be one per 16 hectares (40 acres). In many coun-
tries, a-spacing of from 90-to 300 meters (300 to
1,000 feet) has been employed. (That spacing is
equivalent to one well per two to 22 acres.)
8.5.2 Input Requirements
Input requirements and outputs of geothermal drilling
are defined by the required number of production wells. The
requried number of wells depends on the characteristics and
type of geothermal resource and on the proposed utilization of
the geothermal fluid. In this analysis, the geothermal fluid
is used to produce 100 MW of electric power. Four resource
developments are analyzed:
1) a 150°C liquid-dominated resource using a
binary-fluid cycle for power production;
2) a 150°C liquid-dominated resource using
direct steam flashing for power production;
3) a hot rock development utilizing a pressurized
fluid at 250°C with a binary-fluid cycle for
power production;
4) a vapor-dominated system similar to The
Geysers.
The liquid-dominated resource at Wairakei, New Zealand,
uses a direct steam flashing cycle to produce electricity. In
-74-
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1971, 61 wells supplied a power plant producing 160 MW .l Based
on the facility at Wairakei, 38 production wells are required
for a plant producing 100 MWg. Milora and Tester2 prepared de-
signs for both flashed steam and binary fluid cycles using a
1508C geothermal fluid. A binary-fluid cycle was estimated to
require approximately 4400 Ib/sec geothermal fluid, while a
flashed steam cycle3 required a geothermal fluid flow of about
4800 Ib/sec. Based on a conservative well flow rate of 100
Ib/sec, flashed steam and binary-fluid cycles power plants re-
quire 48 and 44 production wells, respectively. **
A binary-fluid cycle using a 250°C fluid requires a fluid
flow of about 1450 Ib/sec.5 Milora and Tester assumed a well
fluid flow of about 300 Ib/sec.6 Thus, approximately five
production wells are required for this development scheme for
the utilization of energy stored in hot rock.
At The Geysers, 75 wells produce steam sufficient for the
generation of 502 MW0. A 100 MWe development would require
15-20 wells.7
Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy"! Prepared
for U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 46.
2Milora, S. L. and J. W. Tester. Geothermal Energy as a
Source of Electric Power; Thermodynamic and Economic Design
Criteria"! Cambridge, Massachusetts: The MIT Press, 1976.
3With a heat rejection temperature of 27"C.
"Milora, S. L. and J. W. Tester, op.dt.
5Ibid., p. 103.
6ibid., p. 93.
7Resource Planning Associates, Inc. ,op.dt. t p. 20.
-75-
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Reinjaction wells may also be required to dispose of "spent"
geothermal fluids. At The Geysers, one large reinjection well
can dispose of wastewater from each 100 MWe generating facility.1
The FEA2 and Anglin3 have anticipated one reinjection well for
every two production wells of a liquid-dominated geothermal
fluid. Milora and Tester1* assumed a greater requirement for
reinjection wells on the basis that formation permeability might
limit the reinjection flow rate. In this analysis, Milora and
Tester's conservative estimate of equal numbers of production
and reinjection wells is assumed.5
Production from wells at The Geysers has been observed to
diminish with development. Overall production decreases at
the rate of 14 percent each year.6 To maintain production, new
wells must be drilled at the rate of 14 percent per year.7 Over
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May 1977,
p. 56.
2Federal Energy Administration, Interagency Task Force on
Geothermal Energy. Project Independence Blueprint, Final Task
Force Report: Geothermal Energy.Washington, B.C.:U.S.
Government Printing Office, 19/4, p. D-3.
3Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California;
Water and Land Use Issues. Working Paper No. 2, Jet Propulsion
Laboratory, California Institute of Technology, December 14, 1976,
p. 28.
"Milora, S. L. and J. W. Tester. Geothermal Energy as a
Source of Electric Power: Thermodynamic and Economic Design"
Criteria"! Cambridge, Massachusetts: The MIT Press, 1976.
*lbid.,,p. 92.
6Kruger, P. and C. Otte, eds. Geothermal Energy. Stanford,
CA.: Stanford University Press, 197T!
7The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 54.
-76-
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a thirty year period, an additional 60-80 wells are required to
maintain production at 100 MWe. A similar depletion of water-
dominated systems has not been observed.1 Depletion of water-
dominated systems is expected to vary from site to site. If all
of the spent geothermal fluids are reinjected, the productivity
of the resource may be maintained.2
The above estimated well requirements are summarized in
Table 8-21. These requirements assume an additional 2070 require-
ment for reserve capacity.3'*
Manpower, materials and equipment, finances, water, land,
and ancillary energy requirements for the drilling of geothermal
resources are discussed in the following sections.
8.5.2.1 Manpower
Manpower requirements for developmental drilling of hydro-
thermal convection systems have been prepared by Bechtel Corpora-
tion for the Federal Energy Administration.5 Bechtel's estimates
xThe Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"]! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 58.
2Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 60.
3Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California: Water
and Land Use Issues.Working Paper No.2, Jet Propulsion
Laboratory, California Institute of Technology, December 14, 1976.
**The Futures Group, op. cat., p. 54.
5Federal Energy Administration, Interagency Task Force on
Geothermal Energy. Project Independence Blueprint, Final Task
Force Report: Geothermal Energy.Washington, D.C.:U.S.
Government Printing Office,1974, p. D-5.
-77-
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TABLET 8-21. WELL REQUIREMENTS FOR THE PRODUCTION OF 100 MWe ELECTRIC POWER
Ci'o thermal Resource
1
00
1
1.
2.
3.
4.
Booed
Hot Water
Hot water
Hot Rock
Steam
on data and
Assumes gcothcrmal
Asaunes* geotliermal
d
'Based
SB geothermal
on Ceydera.
Fluid Temperature
150'C
150'C
250'C
240*C
assumptions reported In
fluid requlreaenta of
fluid requirements of
fluid requlreaenta of
Power Production Technology
Binary-fluid
Direct ateaai
Binary-fluid
Direct uee of
text.
4400 Ib/aec.
4800 Ib/aec.
1450 Ib/aec.
cycleb
flashing cycle
cycled
ateaai
Assumes well
^Assumes well
hMay be half
Due to well
Production
44f
48*
5«
15-20*
flow of 100
flow of 300
Required dumber of Wells
Reserve Relnjectlon Additional
llf 44h
12f 4Bh
l' 5 — —
4-5e 1 60-801
Ib/aec.
Ib/aec .
assumed value.
depletion, new wells muat be drilled at 14X per year.
Reported value la total
requirement over 30-year period.
-------
describe the manpower required to drill 34 wells. Estimates
reported herein are simply scaled from those reported by Bechtel.
These estimates describe the following activities:
developing a reservoir model
siting and drilling all wells
performing preliminary well tests and
well-logging
casing and cementing all wells through
the well-head valves to complete shut-in
conducting well-flow tests and chemical
sampling.
Table 8-22 reports the manpower required to complete the above
tasks. The data assume that sixty days are required to drill
and complete each well and that the average well depth is 5000
feet.
8.5.2.2 Materials and Equipment
Current estimates of materials and equipment required for
geothermal drilling are unavailable. Various equipment is
temporarily committed for road construction, drilling pad
construction, sump construction, and drilling. Equipment
required for construction includes heavy bulldozers, road
graders, carry-alls, soil compactors, water trucks, and supporting
lubrication and gasoline trucks. Drilling operations require
heavy-duty oil well drilling equipment. A tower 90-120 feet
high is used to raise sections of pipe successively into position
-79-
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00
o
I
TABLE 8-22. MANPOWER REQUIREMENTS FOR THE DRILLING OF WELLS SUFFICIENT FOR THE
PRODUCTION OF 100 MWe ELECTRIC POWER
Manpower Requirements, Man-Years
Hot Water Resource
Binary-Fluid Cycle*
Reservoir Modeling
Reservoir Engineer
Theoretical Geologist
(icophysiclst
llydrotoglat
(ieochemlst
Applied Mathematician
Mathematical Technician
Draftsman
Well Drilling
Geologist (Core-Logger)
Drilling Superintendent
Rig Foreman
Driller
Pipe-Fitter
Welder
Crane Operator
Truck Driver
(.adorer
Well Testing
Reservoir Engineer
Mechanical Engineer
Geoc demist
Median leal Technician
TOTAL
(1.0 year)
First year
2.2
0.9
0.9
0.9
0.9
2.2
2.2
0.7
5.8
2.9
12.
47.
12.
5.8
2.9
5.8
35.
2.2
4.4
2.2
4.4
150
* (0.2 year)e
Second year
0
0
0
0
0
0
0
0
1.2
0.6
2.3
9.3
2.1
1.2
0.6
1.2
7.0
0.6
1.2
0.6
1.2
29
Hot Water Resource .
Direct Steam Flashing Cycle
(1.0 year)*
First year
2.4
1.0
1.0
1.0
1.0
2.4
2.4
0.8
6.4
3.2
13.
51.
13.
6.4
3.2
6.4
3R.
2.4
4.8
2.4
4.8
170
(0.2 year)*
Second year
0
0
0
0
0
0
0
0
1.3
0.6
2.5
10.
2.5
1.3
0.6
1.3
7.6
0.6
1.3
0.6
1.3
32
lint Rock Resource
Binary-Fluid Cycle
7T.O year)*" ~"(0.2 year)*"
First year Second year
0.2
0.1
O.I
0.1
0.1
0.2
0.2
"°
0.6
0.3
1.3
5.2
1.3
0.6
0.3
0.6
3.9
0.2
0.5
0.2
0.5
17
0
0
0
0
0
0
0
0
0.1
0.1
0.3
1.0
0.3
0.1
0.1
0.1
0.8
0.1
0.1
0.1
0.1
3.2
Dry Steam
Direct Use
(1.0 year)*
First year
0.4-0.6
0.2
0.2
0.2
0.2
0.4-0.6
0.4-0.6
0.1-0.2
1.2-1.5
0.6-0.8
2.4-3.1
9.4-12.
2.4-3.1
1.2-1.5
0.6-0.8
1.2-1.5
7.1-9.2
0.4-0.6
0.9-1.1
0.4-0.6
0.9-1.1
31-40
Resource.
of Steam
(0.2 year)*
Second year
0
0
0
0
0
0
0
0
0.2-0.3
0.1-0.2
0.5-0.6
1.9-2.4
0.5-0.6
0.2-0.3
0.1-0.2
0.2-0.3
1.4-1.8
0.1-0.2
0.2-0.3
0.1-0.2
0.2-0.3
5.7-7.7
Drilling requirement of 99 veils.
Drilling requirement of 108 uelts.
Drilling requirement of II wells.
Source: Federal Energy Administration, tntcragenr.y Task Force on Ceo thermal Energy
Drilling requirement of 20-26 wells; does not Include additional 60-80 wells required over
30-year period, assisting depletion rate of 14X per year.
Duration of effort.
Project Independence Blueprint, Final Task Force Report! Ceothermal Energy.
Washington, D.C.: U.S. Government Printing Office, 1974. p. D-5.
-------
for drilling. Heavy-duty diesel electric generators, mud pumps,
and other drilling accessories are located adjacent to the
tower.l
Materials permanently committed at a well site are the
casing and tubing installed in each well. Based on Figure 8-6,
the total weight of steel committed to each well is 185 tons.2
For a hot water field producing 100 MWe electric power, steel
requirements range from 18,000-20,000 tons. Development of a
hot rock field producing 100 MWe requires only 2000 tons of
steel. Steel requirements for a dry steam field producing
100 MWe amount to 15,000-20,000 tons. These estimates are
based on the well requirements of Table 8-21.
8.5.2.3 •Economics
The cost of drilling and casing geothermal wells is
determined mainly by the type of rock, diameter of the well
and its depth. Milora and Tester have developed a geothermal
well cost model using cost information for oil and gas wells
as a basis for extrapolating the limited available cost data
for geothermal wells.3 This model is reproduced as Figure 8-7.
1Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department of
the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976, pp. 143-149.
2This steel requirement assumes an average casing thickness
of 3/8 inch for the first 4000 feet, with a tubing thickness of
Y3 inch for the entire 6000 feet.
f
3Milora, S. L. and J. W. Tester. Geothermal Energy as a
Source of Electric Power: Thermodynamic and Economic Design
Criteria^Cambridge, Massachusetts:The MIT Press, 1976, p. 82
-81-
-------
1000
; 100
O
u
10
•Geothermal well cost* (1976 est.)
J Including drilling and casing
I ~ 20 cm (8 la) dlam.
3 4
Depth (km)
Note: All cost data in 1976 dollars.
Figure 8-7. Geothermal Well Costs as a Function of Depth.
Reprinted by permission of MIT Press from Stanley L. Milora and
Jefferson W. Tester, Geothermal Energy as a Source of Electric
Power: Thermodynamic and Economic Design Criteria. @ 1976 by the
Massachusetts Institute of Technology.
-82-
-------
Sources of cost data for Milora and Tester's model are reported
below.1'7
Glass8 has reported the cost of a completed steam well at
the Geysers to be approximately $1,000,000 in 1977 dollars.
Components of this cost are shown in Table 8-23.
Estimated well costs for hot water, hot rock, and dry
steam developments are shown in Table 8-24. These costs are
based on cost data from Figure 8-7 and Table 8-23 as applied
to the well requirements tabulated in Table 8-21.
'Altseimer, J. H. "Geothermal Well Technology and Potential
Applications of Subterrene Devices - A Status Review." Los
Alamos Scientific Laboratory Report LA-5689-MS, Los Alamos,
New Mexico, August 1974.
2Greider, R. "Economic Considerations for Geothermal
Exploration in the Western United States." Presented at the
Symposium of Colorado Department of Natural Resources, Denver,
Colorado, December 1973.
31972 Joint Association Survey of the U.S. Oil and Gas
Producing Industry.Section I, Drilling Costs, and Section II,
Expenditures for Exploration, Development and Production,
November 1973.
^1973 Joint Association Survey of the U.S. Oil and Gas
Producing Industry.Section I, Drilling Costs, February 1975.
5Bee Dagum, E. M. and K. P. Heiss. "An Econometric Study
of Small and Intermediate Size Diameter Drilling Costs for the
United States." PNE-3012. Mathematica, Princeton, New Jersey.
Prepared for U.S. Atomic Energy Commission. June 1968.
6Shoemaker, E. M., ed. "Continental Drilling." Report of
the Workshop on Continental Drilling, Albiquiu, New Mexico.
Washington, D.C.: Carnegie Institution. June 1975.
7Hendron, R. Los Alamos Scientific Laboratory, Los Alamos,
New Mexico. .September 1975.
8Glass, W. A. "1977 Drilling Methods and Costs at the
Geysers." Geothermal Resources Council, Transactions. Vol. 1,
May 1977, pp. 103-105.•
-83-
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TABLE 8-23. COMPONENT COSTS OF A COMPLETED STEAM WELL SUNK
TO A DEPTH OF 8000 FEETa
Item Cost
Build road, location, & cellar $ 50,000
Move rig in and out 65,000
Rig operating for 70 days 315,000
Air compressor rental 40,000
Fuel for rig and air compressors 34,000
Excessive drill pipe wear 25,000
Hardbanding drill pipe 3,000
Drill pipe & drill collar inspection 6,000
Water 15,000
Waste disposal 20,000
20" conductor pipe 4,500
13-3/8" casing 52,500
9-5/8" casing 67,500
Cement & services 50,000
Rent 20" Hydril & Rotating Head 10,000
Rent shock sub ft stabilizer 10,000
Rent monel drill collar &
directional instruments 10,000
Drilling mud 30,000
Well head & muffler & flow line 20,000
Miscellaneous transportation 10,000
Logging 8,000
Mud well logging 25,000
Bits 55,000
Miscellaneous 50,000
Direct supervision & overhead 28,OOP
TOTAL $1,003,500
aCosts in 1977 dollars.
Source: Glass, W. A. "1977 Drilling Methods and Costs at
the Geysers." Geothermal Resources Council, Trans-
actions, Vol. 1, May 1977, pp. 103-105
-84-
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TABLE 8-24. ESTIMATED WELL COSTS FOR THE PRODUCTION OF 100 MW ELECTRIC POWER
Resource Development System
1. Hot Water
Binary-fluid cycle
Direct steam flashing cycle
Required Number of Wells
99
108
Well Depth
8,200 ft
8,200 ft
Drilling Costs
$43,300,000*
$47,300,000*
2. Hot Rock
Binary-fluid cycle
11
13,000 ft
$13,000,000e
1
OO
Ul
3. Dry Steam
20-26U
80-106d
8,000 ft
8,000 ft
$20,000,000-$26,000,000
$80,000,000-$106,000,000C
1976 Dollars.
Initial drilling requirement.
"1977 Dollars.
1
Drilling requirement over 30-year period, based on
depletion of 14% per year.
Sources: Milora, S. L. and J. W. Tester. Geothermal Energy as a Source of Electric Power; Thermo-
dynamic and Economic Design Criteria. Cambridge, Massachusetts: The MIT Press, 1976.
Glass, W. A. "1977 Drilling Methods and Costs at the Geysers." Geothermal Resources Council,
Transactions, Vol. 1, May 1977, pp. 103-105.
-------
8.5.2.4 Water
Water requirements during drilling amount to 200-500 barrels
per rig-day, primarily for use as drilling fluid. Using the
average consumption of 375 barrels per rig-day1 and assuming
that sixty days are required to drill each well, the average
water requirement is calculated to be 22,500 barrels per well.
Water requirements for drilling operations for hot water, hot
rock, and dry steam developments are tabulated in Table 8-25.
8.5.2.5 Land
A typical well-drilling operation disturbs about one acre
of land. Efficient operators may disturb only one-half acre,
but one acre is typical.2 At the Geysers, wells are spaced at
about one well per forty acres. At Ahuachapan, El Salvador,
wells are spaced at one per twenty acres, while at Cerro Prieto,
Mexico, the wells are spaced at one well per ten acres.3 Based
on these land disturbances and well spacing requirements, total
land disturbances and requirements can be estimated. These
estimated disturbances and requirements are summarized in
Table 8-26.
Once drilling operations have ended, only a small residual
amount of land is committed to the completed well. The well-
head itself consumes only a small fraction of an acre per well.
federal Power Commission. National Gas Survey, Volume II.
Washington, B.C.: U.S. Government Printing Office, 1973, p. 74.
2Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California:
Water and Land Use Issues. Working Paper No. 2, Jet Propulsion
Laboratory, California Institute of Technology, December 4, 1976,
p. 26.
3lbid., p. 33.
-86-
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TABLE 8-25. ESTIMATED WATER REQUIREMENTS FOR DRILLING WELLS SUFFICIENT TO
PRODUCE 100 MWe ELECTRIC POWER
Resource Development System
Required Number of Wells Estimated Water Requirements'1
1. Hot Water
Binary-fluid cycle
Direct steam flashing cycle
99
108
290 acre-feet
310 acre-feet
t
co
2. Hot Rock
Binary-fluid cycle
3. Dry steam
11
20-26
80-106*
32 acre-feet
58-75 acre-feet
230-310 acre-feet
Represents only water required during drilling phase.
Initial drilling requirement.
-t
'Drilling requirement over 30-year period, based on depletion of 14% per year.
Source: Federal Power Commission. National Gas Survey, Volume II. Washington, D.C.:
U.S. Government Printing Office, 1973. p. 74.
-------
TABLE 8-26. ESTIMATED LAND DISTURBANCE AND REQUIREMENTS FOR DRILLING WELLS
SUFFICIENT TO PRODUCE 100 MWe ELECTRIC POWER
Resource Development System
Land Areas Disturbed
By Drilling
Land Areas Required for
Assumed Well Spacing
1. Hot Water
Binary-fluid cycle
Direct steam flashing cycle
99 acres
108 acres'
990-4000 acres0
1100-4300 acres1
i
oo
00
I
2. Hot Rock
Binary-fluid cycle
3. Dry Steam
a
11 acres
20-26 acres3'c
80-106 acres3'e
110-440 acres
800-1000 acres0
3200-4200 acres(
Based on one acre disturbed per well.
Based on well spacing of 1 well per
10-40 acres.
>
"Initial requirement.
Based on well spacing of 1 well per 40
acres.
"Drilling requirement over 30-year period,
based on depletion of 14% per year.
Source: Anglin, R. L. Potential Power Generation Utilizing the Geothermal Resource
at Heber. Imperial County. California: Water and Land Use Issues.Working
Paper No. 2, Jet Propulsion Laboratory, California Institute of Technology,
December 14, 1976. pp. 26, 33.
-------
There are, however, other land requirements associated with
each well-head, such as service roads, pumps, standby generators,
and the like.1 These land requirements are discussed in Section
8,6, Extraction: Production.
8.5.2.6 Ancillary Energy
Fuel requirements for drilling vary with rig size, type of
rock formation drilled, well depth, and time on well. The Federal
Power Commission has indicated that 900-1800 gallons of diesel
fuel are consumed per rig-day.2 Assuming a fuel consumption of
1500 gallons per rig-day and a drilling time of sixty days, it
is estimated that 90,000 gallons of diesel fuel are required
for the drilling of one well. Estimated energy requirements for
drilling operations for hot water, hot rock, and dry steam
developments are tabulated in Table 8-27.
8.5.3 Outputs
Outputs produced from the developmental drilling of geo-
thermal resources are discussed in the following sections.
Outputs discussed below include air emissions, water effluents,
solid wastes, noise pollution, occupational health and safety
hazards, and odor.
1Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California: Water
and Land Use Issues^Working Paper No. 2, Jet Propulsion
Laboratory,'California Institute of Technology, December 14,
1976, p. 31.
2Federal Power Commission. National Gas Survey, Volume II.
Washington, D.C.: U.S. Government Printing Office, 1973, p. 74.
-89-
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TABLE 8-27. ESTIMATED ENERGY REQUIREMENTS FOR DRILLING WELLS SUFFICIENT TO
PRODUCE 100 MWe ELECTRIC POWER
Resource Development System
Required Number
of Wells
Diesel Fuel
Requirement,l
106 gal
Energy .
Equivalent,
1012Btu
1. Hot Water
Binary-fluid cycle
Direct steam flashing cycle
99
108
8.9
9.7
1.2
1.4
2. Hot Rock
, Binary-fluid cycle
o
3. Dry steam
11
20-26U
80-106(
0.99
1.8-2.3
7.2-9.5
0.14
0.25-0.33
1.0-1.3
o
Based on fuel consumption of 90,000 gallons
diesel fule per well.
bAssumes 140,000 Btu/gal.
'Initial requirement.
Drilling requirement over 30-year
period, based on depletion of 14%
per year.
Source: Federal Power Commission. National Gas Survey, Volume II.
Washington, D.C.: U.S. Government Printing Office. 1973. p. 74.
-------
8.5.3.1 Air Emissions
Sources of air emissions during drilling include: exhaust
from diesel generators; dust and exhaust from vehicles traveling
on access roads; and exhaust of gases contained in the geothermal
fluids. Uncontrolled blowouts, which have occurred infrequently,
also represent a potential source of air pollutants. The most
important of these emission sources are discussed below.
Air emissions from diesel generators are summarized in
Table 8-28. These data are based on the fuel requirements of
Table 8-27 and emission factors published by the Environmental
Protection Agency.l Carbon dioxide emissions are estimated from
the carbon content of the diesel fuel.
In vapor-dominated fields such as The Geysers, dry steam
is released to the atmosphere during well drilling, during
subsequent well cleanout, and again during production testing.
An average well at The Geysers emits about 33 Ib/hour of hydrogen
sulfide during well testing. Each well is cleaned and tested
for approximately twenty days. In that time, over 15,800 Ib
of hydrogen sulfide are emitted from each well.2
Following production testing, the well is discharged
continuously through a bleed line until connections are made
to a power plant. The average steam and hydrogen sulfide flows
JU.S. Environmental Protection Agency. Compilation of Air
Pollutant Emission Factors. Second Edition, Third Printing with
Supplements 1-5.Research Triangle Park, North Carolina:
February 1976, pp. 3,3.3-1, 3.3.3-2.
2Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May
1977, pp. 71-72.
-91-
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TABLE 8-28. TOTAL AIR EMISSIONS FROM THE OPERATION OF DIESEL GENERATORS DURING DRIL-
LING OF GEOTHERMAL WELLS SUFFICIENT TO PRODUCE 100 MWfi ELECTRIC POWER
1
RcKoiirce Development System)
. lint Water
Binary-fluid cycle
Direct steam flashing cycle
Diesel Fuel^
Requirement,
10* gal
8.9
9.7
Air Eailaaloni, Tons
Carbon
Monoxide
650
490
Hydrocarbons
170
1BO
Nitrogen
Oxides
2100
2300
Aldeliydca
31
34
Sulfur
Ox Idee
140
ISO
Participates
ISO
160
Carbon.
Dioxide*"
96.000
100,000
2. lint Ruck
Binary-fluid cycle
0.99
SO
19
230
3.S
15
17
11.000
VO
ro
i
' Steam
1.8-2. 3d
7.2-9.5*
92-120
370-480
34-43
130-180
420-540
1700-2200
6.3-8.1
25-33
28-36
110-150
30-39
120-160
19,000 -
25,000
78,000 -
100,000
"fiaard on fuel consumption of 90,000 gallons dleeel fuel per well.
Baaed on EPA emission factors; carbon dioxide emlaalona estimated
from carbon content of dltsel fuel.
Sources: U.S. Environmental Protection Agency. Compilation of Air
Pollutant Emission Factors. Second Edition, Third Printing
with supplements 1-5. Research Triangle Park, North Carolina.
February 1976. pp. 3.3.3-1, 3.3.3-2.
Reid, W. T. «t al. "Meat 0eneration and Transport." Chemical
Engineers' Handbook Fifth Edition. R. H. Perry and C. H.
Chlltun, eds. New York: McCraw Hill Book Co. 1973.
pp. 9-9, 9-10.'
CCalculated by using fuel density of 41.S*API (specific gravity of 0.82).
carbon content of fuel of 86X. All carbon was assumed to be conbusted to
carbon dioxide.
Initial requirement.
'Drilling requirement over 30-year period, based on depletion of 14Z per year.
-------
through the bleed line are small, only about 990 Ib/hour and
0.22 Ib/hr respectively. However, the period of discharge is
variable and can be as long as several years.1
Total emissions of steam from well drilling, cleanout, and
production testing are shown in Table 8-29. These estimates
represent total quantities of steam released to the atmosphere
prior to power plant operation. Noncondensable gases are
currently uncontrolled at The Geysers during well drilling,
cleanout, and production testing. Emissions of particulate
matter are controlled by the injection of water into the "blow-
line" and the use of mufflers.2
Uncontrolled blowouts occur infrequently, but can be a
significant source of air pollution. One such uncontrolled
blowout at''The Geysers has emitted 4000 tons of hydrogen sulfide,
5000 tons of methane, and 6000 tons of ammonia between 1957 and
1975. This is equivalent to about one-eighth the total that
would have been emitted from a 100 MWe Geysers facility operating
over the same period without special controls.3
Estimates of emissions from the development of liquid-
dominated systems can be prepared only from a detailed site-
specific analysis of the chemistry of the geothermal fluid.*
Characteristics of geothermal fluids from several U.S. geothermal
fields have been previously described in Section 8.3.4. However,
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 72.
3Ibid.
''ibid. . p. 74.
-93-
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TABLE 8-29. TOTAL EMISSIONS OF GEOTHERMAL STEAM DURING DRILLING,
CLEAN-OUT, AND PRODUCTION AT THE GEYSERS FOR A
WELL CAPACITY OF 100 MWe IN ELECTRIC POWERa
Constituent
Steam
Carbon dioxide
Ammonia
Methane
Hydrogen sulfide
Nitrogen and argon
Hydrogen
Concentration, wt. %
99.0
0.79
0.07
0.05
0.05
0.03
0.01
Quantity Emitted, tons
1,330,000
10,600
940
670
670
400
130
Scaled from data for 1000 MWe complex.
Sources: Resource Planning Associates, Inc. Western Energy Resources and
the Environment; Geothermal Energy. Prepared for U.S. Environ-
mental Protection Agency, Contract No. 68-01-4100. Washington, B.C.:
U.S. Environmental Protection Agency, May 1977, p. 72.
Teknekron, Inc. "Fuel Cycles for Electric Power Generation."
Comprehensive Standards; The Power Generation Case. EPA No. 68-01-0561.
Washington, D.C.: U.S. Environmental Protection Agency, 1975.
Finney, J.P., F.J. Miller, and D.B. Mills. "Geothermal Power Pro-
ject of Pacific Gas and Electric Company at The Geysers, California."
IEEE Trans. Power App. Systems PAS-92 (1973): 108-115.
-94-
-------
these resource characterizations are not sufficient to produce
reliable estimates of air emissions during geothennal drilling.
During well drilling and production testing, steam flashed
from the geothermal hot waters may represent 20-25 percent of
the total fluid, depending on the fluid temperature. For
comparable levels of electricity generation, the total quantities
of gases emitted to the atmosphere during drilling and production
testing are probably comparable to emissions from The Geysers.
Since hot water wells in some fields can be completely shut off
after production testing, well bleeding prior to power plant
operation may not be an air pollution source.1'2
Mercury and radon-222 are among the more important trace
constituents of geothermal fluids. These elements are toxic
even at low concentrations. Mercury is washed from the atmosphere
by rain and can be absorbed into living organisms from water or
through the food chain. Radon is the precursor of highly toxic
but short-lived decay products. Typical concentrations of these
contaminants have not been reported.3
S-.5.3.2 Water Effluents
Drilling mud and geothermal fluids are the major liquid
effluents from well drilling. Muds used in well drilling may
contain certain toxic additives. The muds are also usually
Resource- Planning Associates, Inc. Western Energy Resources
and the Environment; Geotherroal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 74.
Department of the Interior. Final Environmental Statement
for the Geothermal Leasing Program.Volume I of IV.Washington,
D.C.:U.S. Government Printing Office, 1973.
3Resource Planning Associates, Inc., op.cit., pp. 68, 71.
-95-
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very basic (pH up to 10) from the addition of sodium hydroxide.1
Typically, drilling mud is 9570 water.2 Based on the water
requirements for drilling (see Section 8.5.2.4), approximately
23,700 barrels (approximately 3 acre-feet) of mud are used at
each well. To prevent the contamination of surface waters, the
drill mud must be contained. At The Geysers sumps with impervious
linings or steel tanks are used to contain these liquid wastes.3
The water is eventually evaporated from the mud, which can then
be land-filled.
A significant quantity of geothermal fluids is brought to
the surface during drilling and well testing. Jones and Stokes
Associates have reported that as much as 34,100 cubic meters
(approximately 28 acre-feet) of liquid from a liquid-dominated
geothermal field may be discharged at the surface. The geothermal
fluid may be stored on site in the mud sumps or discharged into
the surface drainage system. ** Some sample characterizations of
these geothermal fluids have been reported in Section 8.3.4.
Quantities of liquid effluents from drilling for hot water,
hot rock, and steam geothermal developments are summarized in
Table 8-30.
1Jones and Stokes Associates. Geothermal Handbook.
Prepared for U.S. Fish and Wildlife Service, U.S. Department of
the Interior, Contract No. 14-16-0008-968. U.S. Government
Printing Office, June 1976. p. 146.
2Campbell, M. D. and J. H. Lehr. Water Well Technology.
New York: McGraw-Hill Book Company, 1974, p. 585. '
3Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, pp. 54-56.
"Jones and Stokes Associates, op.cit., p. 155.
-96-
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TABLE 8-30. ESTIMATED QUANTITIES OF WATER EFFLUENTS PRODUCED DURING
DRILLING AND TESTING OF WELLS SUFFICIENT FOR THE
PRODUCTION OF 100 MWe ELECTRIC POWER
Geothermal Resource
Drilling Mud'
Geothermal Liquids
1. Hot Water
Binary - fluid cycle
Direct steam flashing cycle
300 acre-feet
320 acre-feet
1500 acre-feet
1700 acre-feet
2. Hot Rock
Binary - fluid cycle
33 acre-feet
3. Steam
60 - 78 acre-feet
240 - 320 acre-feetd
aDrilling mud effluents based on 3 acre-feet/well.
Geothermal liquids are brought to the surface during drilling and testing. Reported
values assume that effluents originate only from production and reserve production
wells. No geothermal liquids are produced from hot rock or steam developments.
rt
Initial wells only.
Due to well depletion, new wells are drilled at 14% per year. Reported value des-
cribes drilling effluent over a 30-year period.
Sources: Federal Power Commission. National Gas Survey, Volume II. Washington, D.C.:
U.S. Government Printing Office.1973, p. 74.
Jones and Stokes Associates. Geothermal Handbook. Prepared for U.S. Fish
and Wildlife Service, U.S. Department of the Interior, Contract No. 14-16-008-968
U.S. Government Printing Office, June 1976, p. 155.
-------
Additional contamination of surface and subsurface waters
may occur from well blowouts. Blowouts are infrequent events
caused by well casing failure. Flow of geothermal fluids
from blowouts can amount to as much as 10 acre-feet per day.
Blowouts can be prevented by proper design and drilling opera-
tion.1 The frequency of blowouts at The Geysers appears to be
comparable to the incidence of blowouts in New Zealand, where
about 175 wells were drilled with three blowouts. The more
severe blowouts occurred before 1960, and the performance record
has since improved. Although blowouts can be expected to occur,
the probability of a significant blowout can be reduced by
technological refinements, drilling control measures, and
increased operating experience.2
8.5.3.3 Solid Wastes
The only solid wastes generated during drilling operations
are drill cuttings and mud. For a 5000-foot well, the volume
of these cuttings amounts to about 0.1 acre-feet. The drilling
of wells for the development of hot water systems capable of
supplying 100 MWe electric power produces 10-11 acre-feet of
drill cuttings. The drilling of wells for 100 MWe hot rock
developments produces only about one acre-foot of cuttings.
The,initial drilling of wells for a 100 MWe steam development
produces 2-3 acre-feet of cuttings; over a 30-year period, 8-11
acre-feet are produced. These wastes are typically disposed
in mud sumps, which are then dried and graded or plowed under.
Oarlock, D. and R. L. Wallar. "An Environmental Overview
of Geothermal Resources Development." Geothermal Resources
Development Institute. Rocky Mountain Mineral Law Foundation.
Boulder, Colorado:Rocky Mountain Mineral Law Foundation,
Jan. 27-28, 1977, pp. 14-5, 14-22.
2U.S. Department of the Interior. Final Environmental
Statement for the Geothermal Leasing Program, 4 Vols.
Washington:Government Printing Office, 1973, pp. III-9, 11.
-98-
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8.5.3.4 Noise Pollution
Noise levels during well drilling, cleaning, and testing
have been previously described in Section 8.4.3.2. Additional
noises generated during well bleeding and during blowouts are
reported below:1'2
Operation Duration Noise Level Distance
Well bleeding before Variable
power generation
open hole 86 dBA 5 ft
rock-filled ditch 65 dBA 5 ft
Blowouts Infrequent 118 dBA 50 ft
(Variable)
8.5.3.5 Occupational Health and Safety Hazards
Health and safety hazards associated with geothermal
drilling are principally worker exposure to toxic gases and
drilling accidents. Typical drilling operations pose relatively
minor hazards to crew personnel. Injuries associated with
equipment operation on drill rigs are frequent but minor.
Considerable danger is associated with well blowouts; however,
blowouts are relatively rare occurrences.
*Ecoview Environmental Consultants. Draft Environmental
Impact Report for Geothermal Development of Union Oil Company's
Leaseholds on the Upper Part of the Squaw Creek Drainage at the
Geysers, Sonoma County, California.Napa, California: 1974.
2Reed, M. J. and G. E. Campbell, "Environmental Impact of
Development in the Geysers Geothermal Field, U.S.A.", Proceedings
of the Second United Nations Conference on the Development and
Use of Geothermal Resources, San Francisco, CA, May 20-29,1975.
Washington:Government Printing Office, 1976.
-99-
-------
Exposures to hydrogen sulfide and ammonia are believed
to be the greatest potential health hazards. Both of these
gases may be released to the atmosphere in highly toxic con-
centrations. Certain trace gases such as mercury and radon
are of concern because they are toxic even at low concentra-
tions .1 Actual worker exposure to these gases has not been
determined.
8.5.3.6 Odor
Odors at geothennal developments are chiefly associated
with the presence of ammonia and hydrogen sulfide, as described
in Section 8.4.3.6.
The inputs and outputs associated with each of the four
geothennal developments are summarized in Table 8-31.
8.5.4 Social Controls for Obtaining Lands
Following exploration or when geothennal resources are
known to exist (such as in KGRA's) the geothermal developer must
comply with a series of procedures established by regulatory
agencies in order to obtain rights to the lands. As indicated
in the preceding sections, ownership of geothermal lands in
the U.S. may be by federal or state governments, Indian tribes
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May
1977, pp. 68-71.
-100-
-------
TABLE 8-31. SUMMARY OF INPUTS AND OUTPUTS OF DRILLING WELLS SUFFICIENT
FOR THE PRODUCTION OF 100 MW ELECTRIC POWER
e
1
H
O
1
Manpower
• first year
• second yen r
Materials
• steel
Economic; a
Water
Land
• temporarily disturbed
• required for well Bpac.lng
Ancillary F.neigy
(lot Hater /Binary Cycle
150
29
18,000 tons
$4) Million0
290 acre-ft
98 acren
990-4000 acres
8.9 MM gal diesel fuel
Hot Vater/Stem Flashing Cycle
170
32
20,000 tons
$47 Million0
110 acre-ft
108 acres
1100-4100 acres
9.7 MM gal dtesel fuel
Hot Ruck/Binary Cycle
17
3
2,000 tons
$11 ullllon0
32 acre-ft
11 acres
110-440 acres
1 MM gal dlesel fuel
Dry Steaii/Dlrect Dae
31 -40"
6-8 '
15,000-20,000 tonsb
$20-26 pillion '"
$80-106 nil lion
58-75 acre-ft*
230-310 acre-ft1
20-26 acres?
80-106 acres
800-1000 acres,
3200-4200 acres
1.8-2.3 MM gal dlesel fuel*
Outputs
Air KmI us Ions
• dlefld generatnrn
carbon monoxide
|,ydroc,,rb«iiB
nitrogen oxides
aldehydes
fnilfui* oxides
part Iculates
carhnn dioxide
450 tons
170 tons
2100 tons
11 tons
140 tons
1 SO tons
96,000 tons
490 tons
180 tons
2100 tons
14 tonn
150 toiin
160 tons
100,000 tons
50 tons
19 tons
210 tons
1.5 Ions
15 tons
17 tuns
11,000 tons
92-120 tons
370-480 tons6
14-43 tons"
130-180 tons
420-540 tons'
1700-2200 tons
6.3-8.1 tana.
25-13 tons
28-36 tons?
110-150 tons
30-39 tons'
120-160 tons
19,000-25,000 tonsf
78,000-100,000 tons
(Continued)
-------
TABLE 8-31,
SUMMARY OF INPUTS AND OUTPUTS OF DRILLING WELLS SUFFICIENT
FOR THE PRODUCTION OF 100 MWe ELECTRIC POWER (Continued)
1
t-1
o
N3
1
tr<.ii geothcrn.il fluids*
at mm
carbon dioxide
annum la
mi: thane
hydrogen gnlflde
nitrogen and argon
liydroRen
Watrr Effluent*
• drllllnR mud
• gentliormal fluldn
Solid Wanted
• drill cuttings
Noine Pollution
• blowouts (Infrequent)
• well-bleeding (open hole)
Occupational Health and Safety
CMors
DOPH not Include annual drilling
''Over 10 year life.
C19?6 dollnrn.
''l977 dollars.
'initial.
Hot Wnti-r/Blnnry Cyrle
J,ljn,nOO tons
10,61)0 tonn
940 tons
670 ton*
670 tons
400 tons
130 tonn
300 acre- ft
1500 acre- ft
10 ncre-ft
118 dB(A)
86 dB(A)
Not Quantified
II ,S
Nil,
manpower rrqulremcntn.
Hot Hater/Stem Klnnhlng Cycle Hot Rork/Hlnnry Cycle
1.330.000 tons
10,600 tonn
940 tons
670 tonn
670 tons
400 tons
130 tons
320 acre-ft 33 ncre-ft
1700 acrc-ft
11 acre-ft 1 arre-ft
118 dB(A)
86 dB(A)
Not Quantified Not Quantified
H2S Unknown
NHl
Dry Stcnm/IHrpct tine
1,330,000 tons
10,600 tons
940 tona
670 tons
670 tons
400 tons
110 tons
60-78 acre-ft"
240-320 acre-ft
2-3 acre-ft"
8-11 acre-ft
118 dB(A)
86 dB(A)
Not Quantified
HjS
NH
Over 30 years; Includes depletion.
Bnnpd on The (Jeysers,
-------
or individual Indians1, or private individuals or corporations.
The procedures governing how these lands are made available
vary according to the ownership.2 The following sections
describe the rules, regulations, and established procedures
for obtaining lands for geothermal development in the applicable
categories.
8.5.4.1 Federal Lands
The Geothermal Steam Act of 19703 authorizes the Secretary
of the Interior to lease any public, acquired, or withdrawn
lands administered by Interior, or the Department of Agriculture's
Forest Service, and any lands sold by the U.S. if rights to
geothermal resources were retained. If the lands are in a
known geothermal resource area (KGRA) , they are to be leased
by competitive leasing to the highest bidder. Leases for lands
not considered to be within a KGRA may be issued to the first
qualified applicant on a non-competitive basis. The procedures
for leasing these lands are summarized in Table 8-32.
Royalties for geothermal leases on federal lands are set
at a minimum of 10 percent and a maximum of 15 percent of the
amount or value of steam or any other form of heat or energy
sold or utilized by the lessee. In addition, there is a royalty
1 Procedures for acquiring Indian Lands in the case of most
resources are generally the same as those for other federal lands,
except appropriate Indian authorities do have power to veto
leasing decisions. However, tribally or individually-owned
Indian trust or restricted lands, within or outside the bound-
aries of Indian reservations, were removed by Congress from
geothermal leasing under Section 15(c) of the Geothermal Steam
Act of 1970 (84 Stat. 1566 [1970]).
2In some instances, however, ownership of the land does not
indicate ownership or control of the development of the geo-
thermal resource. See Section 8.4.4.
330 U.S.C. §§ 1001 et. seg. (1970).
-103-
-------
TABLE 8-32. SUMMARY OF LEASING FEATURES FOR FEDERAL LANDS
Method
Royalty/Rental
Procedures
Competitive
Lease (KGRA
Lands)
I
M
O
I
Non-competitive
Lease (other
than KGRA lands)
USGS sets royalty rate:
Minimum 10% and maximum
15% of value of produc-
tion; 5% on byproducts
$1.00 per acre rental
with provision for
escalating rate: BLM
USGS sets royalty rate:
Minimum 10% and maximum
15% of value of produc-
tion; 5% on byproducts
$1.00 per acre rental
with provision for
escalating rate; BLM
1)
BLM intent to lease lands or
nominations by others
2) EIS process where required
3) Application to BLM
Payment of one-half bonus bid
Review of application: BLM
Award of lease
Furnish necessary bonds, pay
remainder of bonus bid, pay first
year's rent
Submit plan of operation for USGS
approval
9) Diligent development required
4)
5)
6)
7)
8)
1) Operator files application,
exploration plan, and pays filling
fee: BLM
2) EIS process where required
3) Review of application: BLM and
USGS, to determine which applica-
tions are for lands in KGRA
4) Payment of one year's rent in
advance
5) Award of lease
6) Diligent development required
-------
of 5 percent on by-products derived from production and sold
or used. To encourage production, the Act also stipulates that
the lessee must pay the royalties whether or not he is engaged
in selling the resource.
Rental rates are set at $1.00 per acre per year. However,
another provision to encourage orderly and timely development
provides that beginning in the sixth year of the lease and for
each year thereafter until the production of geothermal resources
in commercial quantities, the lessee is subject to escalating
rental rates.
Geothermal leases extend for a primary term of 10 years
and, if geothermal steam is produced in paying quantities, the
lease shal^, extend 40 years from the date of production. The
lease is then subject to renewal for an additional 40 year term.
The area of the lease is set at a maximum of 2,560 acres and no
individual or corporation can control more than 20,480 acres
per state.
8.5.4.2 State Lands
State leasing procedures are usually similar to those for
federal leases. All the states make a distinction between com-
petitive and noncompetitive bidding lands. (Montana and Wyoming
permit only competitive bids.) The state laws also have provi-
sions concerning termination of leases; suspension; transfer-
ability; and waiver, suspension, or reduction of rents and
royalties which parallel the federal statute. In some re-
spects, however, state provisions are different. For example,
leases are usually for a primary term of up to 20 years, with
a preferential right for renewal, in some cases, up to 99 years.
(An exception is in New Mexico law which provides for an ini-
tial term of only five years, but permits five year renewals
as long as the resources are produced in commercial quantities.)
-105-
-------
State rental provisions are similar to those specified by
federal statute with roughly $1.00 per acre required as the
minimum. On the other hand, state royalty provisions are
somewhat different. While royalties on the gross revenue on
geothermal steam are similar to the 10 to 15 percent provided
for in the Geothermal Steam Act, most states have a higher
royalty rate (up to 10 percent) for by-products found in
geothermal fluids (e.g., minerals, chemicals) than provided
for in the federal Act (5 percent).
The following tables summarize the leasing procedures and
terms of the leases in the six western states containing
geothermal resource. Table 8-33 summarizes competitive leasing
procedures, which are methods for obtaining known geothermal
areas in those states. Note also that the procedures discussed
in Section 8.4.4.2 for exploration of non-known geothermal areas
are in reality a leasing provision. Tables 8-34 through 8-39
give the details of each state's provisions.
8.5.4.3 Private Lands
The leasing of private lands is essentially an individual
transaction between the leasee and the owner of the land. However,
state laws do have some impact on the terms of the arrangement
since state legislation governs contractual arrangements. Even
so, state statutes for regulating private mineral development
are not uniform and the process of negotiation between the land
owner and the developer yields a wide variety of outcomes.
Increasingly, western states view their role in operations
on private lands as one of protecting the life, health, property,
and public welfare, and encouraging maximum economic recovery of
-106-
-------
TABLE 8-33. COMPETITIVE LEASING PROCEDURES FOR KNOWN AREAS
State
Bidding Factors
Designation Criteria
Arizona
Colorado
Montana
New Mexico
Utah
Wyoming
Cash Bonus
Specified by Land
Cotnmis s ioner s
Cash Bonus
Cash Bonus
See Footnote 1
Specified by Land
Commis s ioner s
Geology and/or Competitive
Interest
Specified by Land Commis-
sioners
All Lands Competitively
Leased
Determined by Land Commis-
sioners
See Footnote 1
Specified by Land Commis-
sioners
Utah uses the cash bonus bid for lands newly opened for
geothermal development, other lands are leased by application.
Source: Sacarto, D, M. State Policies for Geothermal Develop-
ment. Denver: National Council of State Legislatures,
November 1976, p. 48.
-107-
-------
TABLE 8-34. ARIZONA GEOTHERMAL LEASE FEATURES1
Item Statutes Summary
Agency Land Department
Requirements
Fees
Rental $1 per acre2
Royalty Not less than 12%%
Duration Five years and as long as producing
Bond
Other Not more than four sections con-
Information fined to six miles square
'Arizona Revised Codes.
2The non-competitive lease has the rental set in the lease terms
and not by statute.
TABLE 8-35. COLORADO GEOTHERMAL LEASE FEATURES1
Statutes Summary
Agency State Land Commissioners
Requirements
Fees
Rental Set in lease
Royalty Set in lease
Duration Set in lease; for commercial
duration
Bond
Other
Information
'Colorado Revised Statutes.
-108-
-------
TABLE 8-36. MONTANA GEOTHERMAL LEASE FEATURES1
Item
Statutes
Summary
Agency
Requirements
Fees
Rental
Royalty
Duration
Bond
Other
Information
§81-2601 State Board of Land Commissioners
§81-2603 Set by board
§81-2605 $1 per acre
§81-2605 Not less than 107» of value of steam
and not more than 57» on produc-
tion
§81-2604 Ten years, and so long as producing
§81-2606 Required at discretion of the Board
§81-2611 If the geothermal developer needs
water he must apply to the Board
§81-2612 If there is a conflict between coal,
oil, gas, or geothermal developers
on state lands, the first issued
lease has priority, but the Board
may amend to fit the situation.
Montana Revised Codes, 1947.
-109-
-------
TABLE 8-37. NEW MEXICO GEOTHERMAL LEASE1
Item
Statutes
Summary
Agency
Requirements
Fees
Rental
Royalty
§7-15-5
§7-15-5
S7-15-7
Duration
Bond
Discretionary
Actions
Other
Information
§7-15-11
§7-15-18
§7-15-26
§7-15-18
§7-15-6
Commissioner of Public Lands
Not less than 640 acres per lease
nor more than 2,560 acres. No
one person may have interest in
more than 25,600 acres.
10% of steam, 2-10% of mineral
sales , 8% of net or energy plant
on site, 2-1070 of gross used for
recreation, and $1 per acre--
minimum royalty of $2 per acre
Primary term of 5 years and renew-
able for another 5 years if pro-
ducing
Bond not less than $5,000 as set
by commissioner
Commissioner may withhold land from
may
ui
lease or require competitive bids
on unknown lands. See #7 above.
Exploration is to follow the pro-
cedure above, if lands are known
to be capable of commercial geo-
thermal production the above
procedure is followed but the
priority goes to the highest com-
petitive bidder,
1 New Mexico Statutes, 1953.
-110-
-------
TABLE 8-38. UTAH GEOTHERMAL LEASE1
Item
Statutes
Summary
Agency
Requirements
Fees
Rental
Royalty
Duration
Bond
Other §73-1-20
Information
§40-6-5
State Land Board
$1 per acre
10% primary, 10% net byproduct
10 years and so long as producing
commercially
The Division of Water Rights may
regulate geothermal wells as
necessary for safety, and maximum
recovery
If developer plans to drill (explor-
atory) , the Board of Oil, Gas, and
Mining has authority to require:
a) security (for plugging)
b) notice of intent to drill
c) filing of well log
Maximum lease 640-2,560 acres, mini-
mum 4 acres
lUtah Code Annotated, 1953.
-Ill-
-------
TABLE 8-39. WYOMING GEOTHERMAL LEASE FEATURES1
Item Statutes Summary
Agency State Land Commission
Requirements
Fees
Rental $2/acre
Royalty 10% primary, 5% byproduct
Duration 10 years, and so long as producing
commercially
Bond
Other Minimum Lease: 640 acres
Information Maximum Lease: 2,560 acres
Wyoming Statutes.
mineral resources. In some western states the Division of Oil
and Gas has been given power to regulate geothermal operations
on private lands. Geothermal developers must comply with all
air and water quality controls of the state. In other words,
the regulations issued by the Division of Oil and Gas are
similar to those applicable to state lands. Most states also
have provisions for controlling the siting and operation of
electric generating facilities, providing another form of
state jurisdiction on private lands.
-112-
-------
8.6 EXTRACTION: PRODUCTION
This section describes the production of geothennal fluids
from completed wells. As described below, the wellhead produc-
tion system collects the geothermal fluid from wells and conveys
it to a power plant or other user. Certain "well stimulation
techniques" are described that may be used to increase the flow
of geothermal fluids or to create cracks in impermeable hot
dry rock formations. The piping network (or "gathering system")
that conveys the geothermal fluid to its point of use is also
described.
8.6.1 Technologies
Various technologies are employed to stimulate the produc-
tion of geothermal fluids from completed production wells.
These technologies and the more conventional technologies used
in the fluid gathering system are successively discussed below.
Well stimulation techniques may be desirable for hydro-
thermal systems that have initially poor formation permeability
or that have diminished fluid production because of solids
deposition in the formation or well.1 Stimulation techniques
include hydraulic fracturing, chemical solvents, chemical
explosives, and (potentially) nuclear fracturing. Hydraulic
fracturing is commonly used by gas and oil producers. It
involves pumping water down wells with a pressure sufficient
'Ewing, A. H. "Stimulation of Geothermal Systems,"
Geothermal Energy. P. Kruger and C. Otte (eds.). Stanford,
CA-Stanford University Press, 1973.
-113-
-------
to crack the rocks at the bottom. These cracks extend as
pumping continues.1'2
After a period of production, the fluid flow from a hydro-
thermal resource may diminish because of the deposition of solids
on the well casing and in the rock formation. Deposits of min-
erals (mainly silica and calcium carbonate) can be removed from
the well casing by re-drilling. The re-drilling can be accom-
plished easily with a light drilling rig. Chemical solvents in-
jected through the well can potentially dissolve the deposited
solids and restore the well to its original production.3
Explosives can be used to fracture impermeable rock forma-
tions and improve the flow of fluid to production wells."'5
Pumps placed within the well can also increase the rate of
fluid extraction. These "downhole" pumps might also be used to
prevent flashing of liquid-dominated fluids, reduce the potential
for scaling, and maintain noncondensable gases in solution.
Downhole pumps are currently being developed.6
1 Smith, M. C. "Introduction and Growth of Fractures in
Hot Rock," Geothermal Energy. P. Kruger and C. Otte (eds.).
Stanford, CAlStanford University Press, 1973.
2The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development^Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Conneticut: The
Futures Group, April 15, 1975, p. 31.
3 Ibid.
"Ramey, H. J., Jr., P. Kruger, and R. Raghaven. "Explosive
Stimulation of Hydrothermal Reservoirs," Geothermal Energy.
P. Kruger and C. Otte (eds.). Stanford, CA-Stanford University
Press, 1973.
5The Futures Group, op.cit.
6Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May 1977,
p. 32.
-114-
-------
Several techniques have been proposed for recovering heat
from hot rock formations. If the hot rock has a high natural
permeability, a fluid may be injected through wells and circulated
through the formation. The heated fluid is then recovered.
Impermeable formations must first be fractured by chemical
leaching, explosive fragmenting, hydraulic fracturing, or a
combination of fracturing techniques. Controlled hydraulic
fracturing creates a system of cracks that resembles a pancake
on edge, as shown in Figure 8-8. Heat may be recovered from the
fractured rock by one of three methods: the alternate injection
and recovery of fluid through a single well; the continuous
circulation of fluid through coaxial pipes in the same well; or
the continuous flow of fluid between two or more wells. If
water is used as the circulating fluid, the geothermal energy
may appear-at the well-head as steam, hot water, or a mixture of
the two.1'2
Geothermal fluids are conveyed from the production wells
to the point of use through a piping network known as a gathering
system. As described by The Futures Group3, the gathering system:
...consists primarily of insulated piping, suitably
anchored to the ground and having expansion loops or
bellows. It also contains cyclone separators, screens,
and filters to remove rock particles and in the case
of vapor-dominated reservoirs, slugs of water that
occasionally are emitted from the well. Mufflers,
safety valves, and steain traps are also installed.
1 Smith, M. C. "Dry Hot Rock Systems." Submitted to
Conference on the Magnitude and Deployment Schedule of Energy
Resources, Portland, Oregon, July 21-23, 1975. 8 pp.
2The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development^Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 31.
-115-
-------
-------
In designing a gathering system, the objective is to
maximize the flow and minimize cost and heat loss.
These objectives are somewhat opposed, since large
diameter piping will decrease pressure loss and
maximize flow, but will also increase the surface
area for heat loss, as well as pipe cost. Instru-
mentation useful in operating a field would include
flow meters, fluid sampling equipment, and instru-
ments for measuring the thermodynamic properties of
the fluid such as temperature, pressure, and enthalpy.
Alternatives to the recovery of geothermal energy by
extracting fluid from the geothermal reservoir are currently
being developed. These include downhole heat exchangers, heat
pipes, and direct energy conversion devices. None of these
devices has been commercially demonstrated for electric power
production.l
8.6.2 Input Requirements
Input requirements and outputs of the wellhead production
system are primarily dependent on the required number of pro-
duction wells. Estimated well requirements for the development
of three hydrothermal and one hot rock resource have been pre-
viously reported in Section 8.5.2. In the production phase of
the extraction of geothermal energy, only the required produc-
tion and reserve wells are considered. These estimated well
requirements are summarized in Table 8-40.
Manpower, materials and equipment, finances, water, land,
and ancillary-energy requirements for the recovery and transport
of geothermal fluids are discussed in the following sections.
JThe Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No.0^836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, pp. 31-32.
-117-
-------
TABLE 8-40. PRODUCTION AND RESERVE WELL REQUIREMENTS FOR THE
GENERATION OF 100 MWe ELECTRIC POWER3
Required Number of Wells
Geothermal Resource Development Production Reserve
1. Hot Water
Binary fluid cycle 44 11
Direct steam flashing cycle 48 12
2. Hot Rock
Binary fluid cycle 5 1
3. Steam 15-20b 4-5b
75-100° 4-5°
Summarized from Table 8-21
Initial well requirements.
°Due to well depletion, new wells must be drilled at 14% per year.
Reported value is total over 30-year period.
-118-
-------
8.6.2.1 Manpower
Manpower requirements for the construction, operation, and
maintenance of a production piping network have been prepared
by Bechtel Corporation for the Federal Energy Administration.1
Bechtel's estimates describe a piping network associated with
34 wells spaced about 1000 feet apart. Estimates reported
herein are simply extrapolated from those reported by Bechtel.
Bechtel's estimates of construction manpower describe the design,
procurement, construction, testing, and start-up of the geothermal
fluid gathering system. Table 8-41 reports the manpower required
to complete the above tasks. Personnel required for the operation
and maintenance of the gathering system are summarized in Table
8-42.
8.6.2.2 Materials and Equipment
Construction of the gathering system demands heavy equipment
to transport and handle pipe, and to prepare pipeline corridors.
None of this equipment is permanently committed to the gathering
system.
Steel in the piping network is the largest material require-
ment of the geothermal fluid gathering system. The piping
requirement is dependent on the well spacing and grid. For
this analysis, an equilateral triangle grid is assumed, with
wells spaced about 1000 feet apart and the power plant centrally
1 Federal Energy Administration, Interagency Task Force on
Geothermal Energy. Project Independence Blueprint. Final Task
Report: Geothermal Energy.Washington, D.C.:U.S. Government
Printing Office, 1974, pp. D-6,7.
-------
TABLE 8-41. MANPOWER REQUIRED TO CONSTRUCT A GATHERING SYSTEM
SUPPLYING A 100 MW~ POWER PLANT
\D
I
Manpower, total man -years
Hot water resource
Binary
Personnel Description fluid cycle
Design
Mechanical engineer
Civil engineer a
Draftsman3
Draft smana
Route surveyor3
Construction
Civil engineer
Foreman"3
Pipefitterb
Welderb
Carpenter*3
Concrete worker"
Dozer operator"
Truck driver*3
Crane operator*3
Insulation installer*3
Inspector (construction)*3
Inspector (nondestruc-
tive testing)*3
TOTAL
1.1
0.5
0.5
0.5
2.0
1.1
2.3
4.9
3.2
1.6
3.2
1.6
3.2
1.6
0.8
0.9
1.0
30
Hot water resource
Direct steam
flashing cycle
1.2
0.6
0.6
0.6
2.2
1.2
2.5
5.3
3.5
1.8
3.5
1.8
3.5
1.8
0.9
1.0
1.1
33
Hot rock resource Steam
resource
Binary Over
fluid cycle Initial 30-year period
0.1
0.1
0.1
0.1
0.2
0.1
0.3
0.5
0.3
0.2
0.3
0.2
0.3
0.2
0.1
0.1
0.1
3
0.4-0.5
0.2
0.2
0.2
0.7-0.9
0.4-0.7
0.8-1.0
1.7-2.2
1.1-1.5
0.6-0.7
1.1-1.5
0.6-0.7
1.1-1.5
0.6-0.7
0.3-0.4
0.3-0.4
0.3-0.4
11-14
1.6-2.2
0.8-1.0
0.8-1.0
0.8-1.0
2.9-3.9
1.6-2.2
3.3-4.3
7.0-9.3
4.6-6.2
2.3-3.1
4.6-6.2
'2.3-3.1
4.6-6.2
2.3-3.1
1.2-1.5
1.3-1.8
1.4-1.9
43-58
Based on 4-month design program
Based on 8-month construction program
Source: Federal Energy Administration. Interagency Task Force on Geothermal Energy. Project
Independence Blueprint Final Task Force Report: Geothermal Energy. Washington, D.C.
U.S. Government Printing Office. 1974. p. D-6.
-------
TABLE 8-42. MANPOWER REQUIRED TO OPERATE AND MAINTAIN A GATHERING SYSTEM
SUPPLYING A 100 MWe POWER PLANT
Manpower, average man-years per
Hot water resource
Binary
Personnel Description fluid cycle
Hot water resource
Direct steam
flashing cycle
Hot rock resource Steam resource
Binary Direct
fluid cycle steam cycle
Operation
Field Operator
1.6
1.8
0.2
0,6-0.7
to
o
i
Routine Maintenance
Foreman 0.2
Pipefitter 0.3
Welder 0.2
Insulation Installer 0.3
Crane Operator 0.2
TOTAL 2.8
Source: Federal Energy Administration.
dence Blueprint Final Task Force
0.2 M) M).l
0 . 4 'x/O 'vO , 1
0.2 ^0 'UKl
0.4 *\/0 M) . 1
0.2 'V'O MD.l
3.2 0.3 ^1.2
Interagency Task Force on Geothermal Energy. Project Indepen-
Report: Geothermal Energy. Washington, D.C.: U.S.
Government Printing Office. 1974. p. D-6.
-------
located.* Assuming an average diameter of 20 inches2 and an
average thickness of 3/a inch, the amount of steel comprising
1000 feet of pipe is estimated to be about 40 tons.3 Assuming
an additional 25 percent for supports and the like, the amount
of steel comprising 1000 feet of pipe is estimated to be 50
tons. Based on this value and the assumed well spacing of
1000 feet, steel requirements for the gathering of fluids from
100 MWe hot water, hot rock, and dry steam developments are
estimated to be:
Hot water resource 2700-3000 tons
Hot rock resource 430 tons'*
Steam resource, initial 950-1300 tons
Steam resource, over 30 years 3900-5300 tons.
8.6.2.3 Economics
Milora and Tester5 have reported cost estimating factors
for the costs of piping from the wellhead to the power plant.
These factors (reproduced in Table 8-43) report piping costs
as a fraction of the costs for drilling and casing wells. The
1Milora, S. L. and J. W. Tester. Geothermal Energy as a
Source of Electric Power: Thermodynamic and Economic Design
Criteria"! Cambridge, Massachusetts: The MIT Press, 1976,
p. 131.
2Various sources indicated pipe diameters of ten to thirty-
six inches; several sizes are used in each gathering system.
3Perry-, R. H. and C. H. Chilton (eds.) . Chemical Engineers'
Handbook. 5th Edition. New York: McGraw-Hill Book Company,
1973, p. 6-66.
''Based on thirty-inch pipe diameter.
5Milora, S. L. and J. W. Tester, op.cat., pp. 80, 131.
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TABLE 8-43. COST ESTIMATING FACTORS FOR PIPING
AS A FUNCTION OF DRILLING COSTS3
Piping cost as a fraction of well cost
Number of wells
1 -
7 -
19 -
37 -
61 -
>
6
18
36
60
90
90
Vapor-
Dominated
0.15
0.23
0.32
0.42
0.47
0.48
Liquid-
Dominated
0.16
0.24
0.34
0.44
0.49
0.50
Dry
Hot rock
0.17
0.25
0.36
0.46
0.51
0.52
Costs include labor, and describe piping from well-head to power plant.
Assumes an equilateral triangle grid with an average well spacing of 200-
300m and the power plant centrally located. Includes re-injection wells.
Variations between liquid- and vapor-dominated and dry hot rock systems
depend on items such as insulation, pipe wall thickness, materials used,
2-phase vs. 1-phase flow, gaseous effluents, and pressure losses.
Assumes a pressurized-water circulating fluid.
Source: Milora, S.L. and J.W. Tester. Geothermal Energy as a Source of
Electric Power; Thermodynamic and Economic Design Criteria.
Cambridge, Massachusetts: The MIT Press. 1976. p. 80.
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factors are based on the total number of wells drilled, in-
cluding those intended as re-injection wells. To estimate the
costs of only the gathering system, one must scale the total
costs of piping by the number of production and reserve wells.
For example, the dry rock development requires the drilling of
11 wells, including five required for injection. The applicable
piping cost factor from Table 8-43 is 0,25: total costs for
piping in this development are 25 percent of the drilling and
casing costs. Costs for the gathering system are estimated as
s/n of the total piping cost.
Using the method illustrated above, one can calculate the
costs for each of the proposed developments. These preliminary
cost estimates are tabulated in Table 8-44, and are based on
drilling costs from Section 8.5.3.2.
8.6.2.4 Water
No water is required for conveying geothermal fluids to a
power plant or other user. Certain well stimulation techniques
(e.g., hydraulic fracturing) have significant but unknown water
requirements. The stimulation of hot dry rock formations requires
make-up water for use as circulating fluid, and in current tests,
for fracturing the rock formation. The geothermal fluid flow in
a 100 MWe hot dry rock development has been estimated as 1450
Ib/sec1 (46 acre-feet per day). Assuming a fluid loss of 5 to
1Milora, S. L. and J. W. Tester, Geothermal Energy as a
Source of Electric Power: "Thermodynamic and Economic Design
Criteria"! Cambridge, Massachusetts: The MIT Press, 1976, p. 102.
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TABLE 8-44. ESTIMATED COSTS OF WELL-HEAD PRODUCTION SYSTEMS
SUPPLYING A 100 MWe POWER PLANT3
Geothermal resource development Cost of well-head
production system
1. Hot water
Binary-fluid cycle $12,000,000
Direct steam flashing cycle $13,000,000
2. Hot Rock
Binary-fluid cycle $ 1,800,000
3. Steam $ 6,100,000-$ 8,000,000C
$37,000,000-$50,000,000d
a!976 Dollars.
Based on method described in text.
clnitial cost.
Cost over 30-year period, based on well depletion rate of
14% per year.
Source: Milora, S.L. and J.W. Tester. Geothermal Energy as a
Source of Electric Power: Thermodynamic and Economic"
Design Criteria"Cambridge, Massachusetts:The MIT
Press.1976.
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to 10 percent,1'2 make-up water requirements are estimated as
2% to 5 acre-feet per day.
8.6.2.5 Land
From discussions with drillers, Anglin3 has concluded that
one-half acre per well is permanently committed to geothermal
fluid recovery and transmission to a power plant or other user.
Included in the above estimate are land areas required for the
geothermal fluid piping network, service roads, pumps, standby
generators and the like. Based on the number of production and
service wells required to supply a 100 MW power plant, the
following areas are assumed to be permanently committed to the
wellhead production network:
Hot water resource 28-30 acres
Hot rock resource 3 acres
Steam resource, initial 9-13 acres
Steam resource, over 30 years 39-53 acres.
8.6.2.6 Ancillary Energy
Fluids from most geothermal reservoirs are free-flowing;
thus, no ancillary energy is required for transporting the
Initial tests indicated loss of 15 percent of injected
water; the recovery rate is expected to improve as the system
is operated.
2Mortensen, J. J. "The LASL Hot Dry Rock Geothermal Energy
Development Project." LASL Mini-Review. July 1977.
3Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California:
Water and Land Use-Issues' Working Paper No. 2, Jet Propulsion
Laboratory, California Institute of Technology, December 14,
1976. pp.31, 35, 37.
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geothermal fluids to the energy user. Quantities of energy re-
quired for certain fracturing techniques, and for down-hole and
surface pumping of low-pressure resources or for maintenance of
one-phase flow are highly variable and have not 'been included.
8.6.3 Outputs
Only a few residuals are associated with the recovery and
transport of geothermal fluids to an energy user. These resi-
duals are discussed in the following sections as air emissions,
water effluents, solid wastes, noise pollution, occupational
health and safety hazards, and odor.
8.6.3.1 Air Emissions
During normal operations, no gas streams are vented to the
atmosphere from the transport of geothermal fluids. Fugitive
emissions of geothermal vapors and gases exist, but have not
been quantified. During plant upsets or shutdowns, essentially
all vapors and gases are vented to the atmosphere. These
emissions are similar to those during production testing, as
previously described in Section 8.5.3.1. Quantities emitted
during upsets are unknown.
8.6.3.2 Water Effluents
During the recovery and transport of geothermal fluids,
there are no water effluents from the well production and
piping network. Some potential exists for the contamination
of ground water as.the geothermal fluid is transported up the
production well. However, this potential hazard can be reduced
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to insignificance oy proper and complete casing of the produc-
tion wells. Rupture of the piping network is rare, but can be
a source of contamination of surface water.
A small waste effluent may be associated with the removal
of solids and particulates from the geothermal fluids. This
effluent has not been quantified but is probably less significant
than other effluents occurring during geothermal energy
development.
8.6.3.3 Solid Wastes
The only solid wastes generated from the wellhead production
system are those solids and particulates removed from the
geothermal fluids at the wellhead. Quantities of these wastes
have not been estimated.
8.6.3.4 Noise Pollution
During normal operation, little noise is associated with
the wellhead production system. Noise levels from a muffled
steam line vent during plant upsets have been reported to be
90 dBA at a distance of 100 feet. During a rare rupture of
a steam line, noise levels of 100 dBA at a distance of 50 feet
are anticipated.1
1Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 65.
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8.6.3.5 Occupational Health and Safety Hazards
Safety hazards associated with the operation and maintenance
of the wellhead production system are likely to be relatively
minor. Health hazards are chiefly associated with worker ex-
posure to toxic gases including H2S and NHa. These have been
previously described in Section 8.5.3.5.
8.6.3.6 Odor
Odors at geothermal developments are chiefly associated
with the presence of ammonia and hydrogen sulfide, as described
in Section 8.5.3.6. Odor levels of these gases in the proximity
to wellhead production systems have not been reported.
The inputs and outputs associated with the wellhead produc-
tion system are summarized in Table 8-45.
8.6.4 Extraction Social Controls
The extraction and development of geothermal resources is
regulated by federal, state, and local government. At each of
these levels, laws, regulations, rules and other policies have
been enacted that directly or indirectly affect the deployment
of geothermal extraction-drilling-production technologies. The
resulting regulatory system can be classified under four basic
headings: planning and land-use activities including the en-
vironmental impact statement process; regulations pertaining to
the health and safety of operations personnel; procedures that
relate to environmental protection and land restoration; and
rules established in the interest of conservation to encourage
orderly and timely development of geothermal resources. These
are described in several jurisdictional levels in the following
sections.
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TABLE 8-45. SUMMARY OF INPUTS AND OUTPUTS ASSOCIATED WITH WELLHEAD PRODUCTION
SYSTEM AT A 100 MWe POWER PLANT
1
M
ro
VO
Input Requirements
Manpower
• Construction
• Operating
Materials
• Steel
Economics
Water
Land
Ancillary Energy
Outputs
Hot Water/
Binary Fluid
30 man-years
3 men
2,700 tons
$12 million
_
28 acres
None- Variable
Hot Water/
Steam Flashing
33 man-years
3 men
3,000 tons
$13 million
_
30 acres
None-Variable
Hot Rock/
Binary Fluid
3 man-years
0.3 men
430 tons
1.8 million
2.5-5 acre ft/d
3 acres
Variable
Dry Steam/
Direct Use
11-14 man years
43-58 man-years
^1.2 men
950-1300 tons*
3900-5300 tons
$6.1-$ 8 million?
$37-$50 million
-
9-13 acres3
K
39-53 acres
None-Var i ab le
Air Emissions
Water Effluents
Solid Wastes
Noise Pollution
• Production
• Muffled Ventc
Occupational Health
and Safety
Odor
Small
Small
Undetermined
Little
90 dB(A)
Not Quantified
NH3
H2S
Small
Small
Undetermined
Little
90 dB(A)
Not Qualtified
NH3
H2S
Small
Small
Undetermined
Little
90 dB(A)
Not Quantified
Unknown
Small
Small
Undetermined
Little
90 dB(A)
Not Quantified
NHj
H2S
Initial
5 Over 30 years
:At 90 feet
-------
8.6.4.1 Federal Planning and Land Use
The Geothermal Steam Act of 1970 excluded certain public,
acquired, and Indian lands from the leasing program because of
their special land values or other unique characteristics. These
include: 1) lands administered by the National Park Service;
2) lands within national recreation areas; 3) lands used for
fish hatcheries; wildlife refuges, wildlife or game range lands,
wildlife management areas, waterfowl production areas, or lands
reserved to protect endangered species; and for tribally or
individually owned Indian trust or restricted lands. Lands ad-
ministered by the Department of Agriculture, and lands withdrawn
under the Federal Power Act may be leased only with the consent
of the administering agency and under the terms stipulated by
the agency.
Prior to a lease sale of geothermal lands, BLM must prepare
an environmental impact statement if the Director of the agency
determines that issuance of the lease would be a major federal
action under NEPA provisions. In so doing, the agency must:
evaluate fully the potential effect of the geothermal
resources operations...on the total environment, fish
and other aquatic resources, wildlife habitat and pop-
ulations, aesthetics, recreation and other resources
in the entire area during exploratory, developmental,
and operational phases...(including) the potential
impact of the possible development and utilization of
the geothermal resources including the construction
of power generating plants and transmission facilities
on lands which may or may not be included in a geo-
thermal lease.*
In this evaluation process, BLM must request and consider
the views and recommendations of all concerned federal agencies;
*43 C.F.R. 3200.0-6, 38 Fed. Reg. 35084 (1973).
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may hold public hearings; and as appropriate consult with state
agencies, organizations, industries, and lease applicants. A
potential factor explicitly stated for consideration is the use
of the land and its natural resources consistent with federal
multiple-use management principles.1 If a decision is then made
to lease, the regulations require that BLM provide "special
terms and conditions to be included in (the lease) as required
to protect the environment, to permit use of the land for other
purposes, and to protect other natural resources."2 Although
framed in discretionary terms, these provisions appear mandatory
when viewed in conjunction with the National Environmental Policy
Act.
The above environmental analysis process generally takes
place prior to the issuance of an exploration permit on KGRA or
competitive lease lands. Generally, an environmental impact
statement is not required for exploration on non-competitive
geothermal lands. A programmatic impact statement has been
issued which covers all geothermal exploration.
If the developer acquires a lease, he is then in a position
to begin developmental drilling. According to applicable regu-
lations , this drilling process requires clearances by USGS
regarding drilling plans and proposals, and compliance with
applicable state laws.
8.6.4.2 State Planning and Land Use
Although most states in the west regulate development of
geothermal resources, only five states have requirements for
>30 C.F.R. 270.11, 270.15 (f), 38 Fed. Ref. 35069 (1973)
238 Fed. Reg. 35084 (1973), 43 C.F.R. 3200.0-6.
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reservoir management. Agencies in each of these states are
given the authority to ensure that development operations do
not needlessly degrade other natural resources of the state and
that the resources are not wasted.* This section will sum-
marize these regulations.
Faced with depletion problems similar to those in oil and
gas production, the states have given their agencies at least
one of three management techniques. These include well-spacing
and pooling, direct production restrictions, and provisions for
the unit operation of reservoirs.
The well-spacing regulations require that the wells be
spread out to a minimum surface area per well (e.g., 40 acres/
well). Additional regulations might require that the wells be
a certain distance from the property line, buildings, roads, or
other wells. A regulated regulatory method is that allowing
"pooling" of separate properties. When a resource owner acquires
control of land which does not total the minimum necessary for
an individual well, by statute he can join a neighbor to reach
the minimum. In a few states "forced pooling" is allowed.
If direct production restrictions apply, the administering
state agency determines the maximum efficient withdrawal for the
reservoir and then prorates the amount in accordance with the
development interests. Over-production of a reservoir can result
in a reduction of ultimate reservoir productivity.
A final type of regulation allows the reservoir owners to
unitize; that is, to produce the reservoir as a whole. Under
unitization each producer benefits from increased efficiency
1Sacarto, Douglas M., State Policies for Geothenaal Develop-
ment. Denver: National Conference of State Legislatures,
November, 1976, p. 55.
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and therefore spacing and production rates are actively and
voluntarily pursued. This reduces the regulatory burden on
states.1 Table 8-46 summarizes the regulatory tools used in
the West to allow for reservoir management.
TABLE 8-46. REGULATORY MECHANISMS IN THE STATES
FOR GEOTHERMAL DEVELOPMENT
State
Arizona
Colorado
Montana
New Mexico
Utah
Wyoming
Source: Sacarto,
Area
Spacing
X
X
-
X
X
X
Douglas M. ,
Pooling Unitization
X X
X
-
X
-
-
State Policies for Geothermal
Production
Restrictions
—
-
-
X
-
X
Development .
Denver: National Conference of State Legislatures, November, 1977,
p. 55.
8.6.4.3 Health and Safety
Both state and federal statutes contain provisions for
safeguarding the life and health of workers and the public.
BLM includes provisions with respect to public safety as part
of the conditions for awarding geothermal leases. USGS enforces
its own stipulations regarding public safety and human health
and safety in operations conducted under BLM geothermal leases.
In addition, the Occupational Safety and Health Administration
(OSHA) promulgates and enforces worker health and safety
regulations in areas not regulated by other federal agencies.
Sacarto, Douglas M., State Policies for Geothermal Develop -
tnent. Denver: National Conference of State Legislatures,
November, 1977, p. 55.
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At present, major occupational health and safety considera-
tions for geothermal extraction technologies parallel those of
the oil and gas drilling system. This is largely because current
drilling equipment, technology, and methods are similar to those
used in oil and gas operations, with modifications to suit the
specific geothermal drilling needs. However, it is also in part
due to the limited state of development of geothermal resources
as a whole. Other necessary standards will probably become more
clearly defined as additional exploratory and extraction drilling
is undertaken.
During test drilling and subsequent production testing, the
possibility of a blowout, in which steam or hot water escape
uncontrolled, poses a hazard which can jeopardize the health and
safety of employees.1 As a result, the lessee is required by
USGS to select the kinds of equipment (e.g., weights and types
of drilling fluids and provisions for controlling fluid tempera-
tures, blowout preventers, other surface control equipment,
casing and cementing materials, etc.) to keep all wells under
control at all times, thereby insuring the safety of life and
property.2 Also, specific requirements related to accident
prevention may be included in the terms of the lease or in
Geothermal Resources Operational (GRO) Orders issued by the
Supervisor. Operating regulations provide that all accidents
(including accidents involving blowouts) on leased land be
reported to the Supervisor within 24 hours and that full reports
be submitted within 15 days.3
*A blowout at the Geysers field in California has remained
uncontrolled for several years because of the danger and expense
to cap the well.
230 C.F.R. 270.40, 38 Fed. Reg. 35070-35071 (1973).
330 C.F.R. 270.46, 38 Fed. Reg. 35071 (1973).
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A related serious health hazard is the sound level of noise
from steam ejection or expansion due to accidental blowout or
during the venting of steam wells after completion. Operating
regulation 240.42 specifies that the welfare of employees and
the public must not be affected as a consequence of the "noise
created by the expanding gases." Federal occupational noise
exposure levels applicable to geothermal operations have been
established,l as well as permissible noise exposure based on the
sound level duration in hours per day. Besides the federal
standards, many states have enacted occupational noise standards
to protect workers. If such state standards are more restric-
tive than federal standards, they will apply to geothermal
activity in lieu of federal standards.2 It is a USGS function
to approve the method and degree of noise abatement adopted by
the lessee.
Noise regulation associated with geothermal development is
imposed by the BLM on federal leases. All geothermal developers
are subject to local noise ordinances, but only one county has
specifically directed regulations at geothermal development.3
Production testing, which is the transitional phase between
exploration and potential development and production, involves
venting of the geothermal well to the atmosphere, with accom-
panying vapor release and, as noted above, noise. This vented
steam often contains (in varying amounts) noncondensable gases
such as carbon dioxide, methane, hydrogen, nitrogen, argon,
carbon monoxide, hydrogen sulfide, radon, ammonia, and vapors
'29 CFR 1910, Section 6(a) and 8(g).
Department of the Interior. Final Envirpnme_ntal_ Statement
for the Geothermal Leasing Program. Volume I of IV.Washington,
D.C.: U.S. Government Printing Office, 1973, p. 111-62.-
3Although not part of this study, Imperial County, Califor-
nia has a noise abatement component to its geothermal ordinance.
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such as boron and mercury.1 The toxicity of these gases varies,
but at least one potential hazard would be both the toxicity and
nuisance odor of hydrogen sulfide. Under normal climatic and
topological conditions, hydrogen sulfide would mix with the atmo-
sphere and would not tend to accumulate locally. However, under
stagnant air or temperature inversion conditions , the gas could
accumulate locally to a high nuisance level, and perhaps a toxic
level.2 Under extreme conditions, some of the other gases present
in geothermal fluids could pose similar threats to operating
personnel. As a result, during production testing, considerable
monitoring and analytical work is required for evaluating the
potential risk and for establishing control measures needed to
assure that federal and state public health and safety require-
ments are met.
An additional health and safety hazard encountered during
field development is the use of asbestos, alone and in combina-
tion with fiberglass, as insulation material around pipelines,
as a sheathing material on cooling towers, and for various other
purposes. If airborne asbestos fibers are sufficiently concen-
trated in enclosed fabricating and storage areas, and are inhaled
by workers, they could pose a health hazard. Thus, as with
noxious gases, monitoring is required at fabrication and storage
areas and during field installation to assure health and safety
protection.3
Department of the Interior. Final Environmental Statement
for the Geothermal Leasing Program. Volume I of IV. Washington,
D.C. : U.S. Government Printing Office, 1973, p. III-ll.
zlbid., p. 111-14.
*Ibid., p. 111-27.
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8.6.4.4 Environmental Protection and Restoration
Alleviation of potential environmental impacts resulting
from geothermal exploration and development operations is
accomplished under the applicable federal, state, and local laws
and regulations, geothermal leasing and operating regulations,
Geothermal Resources Operational (6RO) Orders issued by the
Supervisor (an authorized representative of the Secretary of the
Interior), and other lease and land-use permit provisions.
Section 8.5.4.1 above described the provisions for initial
environmental analysis as specified in the leasing regulations.
In addition to these procedures which establish the framework
within which all exploration and development operations are to
be conducted, specific environmental protection measures are
included throughout the regulations. These will be discussed
below.
General Considerations
The basic federal requirement is that lessees (including
operators) take all reasonable precautions to prevent any
environmental pollution or damage, including damage to trees,
other vegetation, natural resources, fish and wildlife and their
habitat.l In addition, a subsequent section provides that geo-
thermal developers must comply with all "federal and state
standards with respect to the control of all forms of air, land,
water, and noise pollution, including, but not limited to, the
control of erosion and the disposal of liquid, solid, and
gaseous wastes.2 This section also grants the Supervisor dis-
cretionary authority to establish additional and more stringent
standards which must be met.
'30 C.F.R. 270.30, 38 Fed. Reg. 35069 (1973).
230 C.F.R. 370.41, 38 Fed. Reg. 35071 (1973).
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Environmental problems and impacts stemming from geothermal
resources development are to be mitigated as indicated under
operating regulations.1 The former Section (30 CFR 270.11) gives
the Supervisor authority to issue written GRO orders to implement
regulations insuring protection of the environment, while the
latter Section provides, among other things, that authorized
field officials of Interior shall inspect and supervise geothermal
operations to insure implementation of regulations to prevent
unnecessary damage to natural resources, to prevent degradation
of water quality, and to protect air, wa.ter and other environmen-
tal qualities.2 This includes inspection and control of activ-
ities which might cause subsidence of the land surface to deter-
mine if the potential subsidence is unacceptable. The Supervisor
may also prescribe or approve variances from previous GRO orders
when necessary for environmental protection.3 Stipulations
regarding emissions and effluents issued by USGS, BLM, and other
concerned agencies are enforced by USGS. Also the Forest
Service and the Bureau of Sport Fisheries and Wildlife (BSFW)
can make recommendations concerning emission and effluent stipu-
lations to be included in BLM geothermal leases and to be enforced
by USGS.1*
Air Quality
The basic provisions for air pollution control are included
in the leasing regulations, Sections 3204.1 (c) (3), 3204.1 (c)
(5), and 3210.2-1, and in the operating regulations, Section
'30 C.F.R. 270.11 and 270.12.
238 Fed. Reg. 35069 (1973).
330 C.F.R. 270.48, 38 Fed. Reg. 35071 (1973).
"Doub. Federal Energy Regulation. 1974: H-28.
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270.30, 270.40, 270.41, and 270.46. Geothermal development must
also conform to various federal guidelines dealing with air
quality as established by EPA. State ambient air quality
standards are likewise applicable.1 In those western states
with potential for geothermal development, air quality standards
for the most part apply only to carbon monoxide and particulates
(some states have, however, promulgated standards for dust and
hydrogen sulfide). In addition to these ambient criteria, any
geothermal development that occurs in certain designated state
air basins must comply with any additional standards for that
basin.2
Only one national standard could potentially be violated by
geothermal development: the National Primary Standard for carbon
monoxide of 10 milligrams per cubic meter for a maximum eight
hour concentration not to be exceeded more than once per year.3
The main air pollutant emitted during geothermal operations/
development is hydrogen sulfide. As of January 1977, of the
eight western states, Montana, New Mexico, North Dakota, and
Wyoming had set hydrogen sulfide standards." In addition Utah's
limits on sulfur compound emissions may pose some limitations
*In a recent case the U.S. Supreme Court held that EPA must
enforce state standards on federal activities through EPA's regu-
lations - this being true fro air or water regulations. See
Hancock vs. Train. 426 U.S. 167 (1976), and EPA ys. California
ex rel Water Resources Board. 426 U.S. 200 (1976).
Department of the Interior. Final Environmental Statement
for the Geothermal Leasing Program. Volume I of IV. Washington,
B.C.:U.S. Government Printing Office, 1973, p. 111-54.
3U.S. Clean Air Act Amendments of 1970.
"*Tarlock, A. Dan, and Richard L. Waller. "An Environmental
Overview of Geothermal Resources Development." Geothermal
Resources Development Institute. Boulder, Colorado.- Rocky
Mountain Mineral Law Foundation, 1977, p. 14-31.
5Ibid.
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upon geothermal development.5 However, other states could
easily limit hydrogen sulfide pollutants by the use of odor
regulations1 specifically or by a common law nuisance action.
Water Quality
With respect to water resources, Section 3204.1 (c) (2) of
the leasing regulations and Section 270.41 of the operating
regulations for geothermal development require lessees (including
operators) to conduct all activities in compliance with federal
and state water quality standards. Geothermal leasing regula-
tions further specify: "Toxic materials shall not be released
into any surface waters or underground waters. Reinjection of
waste geothermal fluids into geothermal or other suitable
aquifers will be permitted upon approval (of the Supervisor)."2
Water quality problems associated with geothermal develop-
ment are regulated by two different methods. One type of
regulatory framework is the federally guided state programs as
discussed in Chapter 2. These include the FWPCA and the Safe
Drinking Water Act (SDWA). The remaining method of handling water
pollution is the use of common law causes of action (e.g.,
nuisance).
Water pollution control under the nuisance causes of action
can be either by negligence or strict liability. Because the
type of water pollution resulting from geothermal resource
development is similar to that from oil and gas operations a
comparison of social controls would be beneficial. As one
source has noted, salt water disposal pit overflow or the escape
Regulations are in effect in Colorado, Montana, South
Dakota, and Wyoming.
243 C.F.R. 3204.1 (c) (2), 38 Fed. Reg. 35088 (1973).
-------
of gas from a well have been held to constitute negligence and
similar results could occur in geothermal.l The strict liability
for damages has been imposed in oil and gas law only in cases of
violation of duties imposed by statutes or administrative order.
Brine disposal can be handled by a National Pollutant Discharge
Elimination System (NPDES) permit, where the federal or state
government will issue the permit if the waters are cleaned to
acceptable levels.2
An additional problem with discharge of the brine into sur-
face waters is the high heat content of geothermal wastes.
Court interpretation of EPA's method of controlling heat dis-
charges is not clear. EPA had banned the use of cooling lakes
(where a stream flow is impounded), but in a recent case EPA
was required to look again at the decision.3 The court said the
decision conflicts with the Congressional policy of conserving
water in the arid West. Further the court required EPA to look
at the costs and benefits derived from the required cooling
/
technologies compared to other alternatives.
Because the reinjection of brines into the geothermal
reservoir helps maintain the reservoir pressure, that is the
preferred method of disposal. Further, the deep well injection
avoids contamination of surface and ground waters."1 EPA
Oarlock, A. Dan, and Richard L. Waller. "An Environmental
Overview of Geothermal Resources Development." Geothermal
Resources Development Institute. Boulder, Colo.: Rocky Mountain
Mineral Law Foundation, 1977, p. 14-23.
2For some discharges, effluent limitations have been estab-
lished (e.g., waters pumped out of coal mines), but as of yet
none have been written for geothermal development. See ibid
pp. 14-25. In that case limitations can be set on an ad hoc basis.
3Appalachia.vs. Train. 545 F.2d 1351, 9 ERG 1033, Modified
9 FRC 1974 (4th Cir. 1976).
"Federal geothermal lessees can be allowed by the BLM geother-
mal supervisors to use reinjection. 40 CFR S 124.80, 125.26 (1975)
-141-
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initially asserted jurisdiction over underground injection under
the FWPCA but a court decision limited the jurisdiction to only
injections that might cause surface water pollution.1 Congress
subsequently passed the Safe Drinking Water Act giving EPA
authority to require state programs to control underground
injection.2 Regulations on underground injection have not yet
been issued.
State control of geothermal reinjection is unclear. Since
the FWPCA required the states to include a provision in their
laws to allow control of underground injection prior to EPA
approval of their program, the states of Colorado, Montana,
North Dakota, and Wyoming have such provisions.3 Unfortunately,
the provisions were written prior to a serious interest in
geothermal development and the application is debatable.
Questions which have been identified, for example, include: Is
brine returned to a geothermal reservoir system a "pollutant"?
Is the geothermal reservoir part of the waters of the state?1*
Biotic Resources
In the case of biotic resources, the federal leasing regula-
tions are flexibly written to include provisions for appropriate
protection measures. Due to the diversity of vegetative cover,
*U.S. vs. GAP Corp. . 389 F. SUDD. 1379 CS.D. Texas 1975).
2Eckert, EPA Jurisdiction Over Well Injection Under the
Federal Water Pollution Control Act, 9 NAT. RESOURCES L. 455
(1976).
3See Section 2.9 of Chapter 2.
"Tarlock, A. Dan and Richard L. Waller. "An Environmental
Overview of Geothermal Resources Development," Geothermal
Resources Development Institute, Boulder; Colorado: Rocky
Mineral Law Foundation, 1977, pp. 14-28.
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fish and wildlife habitats and populations, it is not possible to
establish a single all-encompassing set of provisions to adequately
cover all situations. However, measures to protect fish and wild-
life and their habitat, and to restore all disturbed lands in an
approved manner are contained in 43 CFR Section 3204.1 (g) and
(i). These measures are to be established on a site-specific
basis and included as special stipulations in each lease or as
GRO's. Water quality measures, as discussed above, must also
provide for the protection of fish and other water-related
wildlife factors. Likewise, special noise control stipulations
may be required if there are critical wildlife factors such as
nesting, mating, migration routes, to be considered for the
area under development.1
Land Restoration
It is inevitable that lands and related vegetation will be
disturbed as a result of geothermal development. Consequently,
numerous provisions for the restoration of land surfaces upon
abandonment or termination of geothermal activities are included
in the operating and leasing regulations. Federal operating
regulations stipulate that the lessee must comply with all
federal and state standards with respect to land pollution, the
control of erosion, and the disposal of liquid, solid, and
gaseous wastes.
Proper reclamation and revegetation during development as
well as at completion are stressed. For example, when no longer
needed, pits and sumps are to be filled and covered and the
premises restored to "a near natural state'1 as prescribed by the
Department of the Interior. Final Environmental Statement
for the Geothermal Leasing Program. Volume I of IV. Washington,
B.C.:U.S. Government Printing Office, 1973, pp. 111-77, 78.
-143-
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Supervisor.1 Operating regulations further stipulate that "the
premises at the well site shall be restored as near as reasonably
possible to its original condition immediately after plugging
operations are completed on any well, except as otherwise
authorized by the Supervisor."2
Additional measures to rectify land damage on federal lease
are contained in the leasing regulations. Section 3204.1 (i)3
requires restoration of all disturbed lands; Section 3244.1 (2)
(a) provides that upon relinquishment of a lease, a statement
must be submitted as to whether the relinquished land has been
disturbed and whether it was restored according to the terms of
the lease; and Section 3204.1 (d) additionally requires that the
developer remove or dispose of all waste, including but not
limited to, human waste, trash, garbage, refuse, petroleum pro-
ducts, and extraction and processing waste generated in connection
with the operation, in a manner acceptable to the Supervisor.
GRO orders may be issued as necessary to entail specific land
reclamation activities not covered in the leasing or operating
regulations. Site-specific revegetation methods may also be
specified by GRO order or lease stipulation.
Well Abandonment
Notice of intention to abandon any well (whether a drilling
well, geothermal resources well, water well, or dry hole) must
be filed with and approved by the Supervisor. Operating regula-
tions require that the lessee shall "promptly" plug and abandon
any well that is not used dr useful. Abandonment work must be
a30 C.F.R. 270.44, 38 Fed. Reg. 35071 (1973).
230 C.F.R. 270.45, 30 Fed. Reg. 35071 (1973).
30f Chapter 43, Code of Federal Regulations.
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conducted so as to preserve fresh water aquifers and prevent the
intrusion of saline or polluted waters into these aquifers.
After work is completed, the operator has 30 days to file a
report of abandonment.1
8.6.4.5 Conservation
Both federal and state statutes emphasize avoiding waste
during geothermal extraction and development. In terms of
resource conservation, the Secretary has broad authority under
federal laws and regulations to withdraw or otherwise exclude
certain public lands from leasing and development.2 BLM under
its operational regulations is authorized and directed to "ensure
that all operations, within the area of operations, will conform
to the best practice and are conducted in such manner as to
protect the deposits of the leased lands and to result in the
maximum ultimate recovery of geothermal resources, with minimum
waste..."3 In addition, Section 3204.,2 of the leasing procedures
requires that the lessee (including operators) use all reasonable
precautions to prevent waste of geothermal and other natural
resouces found or developed in the area of the lease.
'30 C.F.R. 270.45 and 270.72 (f) (f), 38 Fed. Reg. 35071-
35072 (1973).
243 C.F.R. 3201.1-2, 38 Fed. Reg. 35014 (1973).
330 C.F.R. 270.11, 38 Fed. Reg. 35069 (1973).
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8.7 USES OF GEOTHERMAL ENERGY
Estimates of the near-term development potential of
geothermal energy vary widely. One view holds that geothermal
energy is most important for electricity generation, but only
in certain local areas or in under-developed countries seeking
alternatives to even'more expensive energy sources. The
counterview holds that geothermal energy has the greatest
potential in direct thermal or other non-electric applications.1
In 1976, electricity generating capacity from geothermal
resources amounted to about 1360 MWe worldwide.2 Worldwide,
the largest non-electric uses of geothermal energy were heating
and irrigation in greenhouses, representing over 5500 MW^ average
energy consumption.3
This chapter describes both electric and non-electric use
of geothermal energy. Alternatives for electric power genera-
tion are discussed in Section 8.7.1. Input requirements and
outputs for power generation are discussed in Sections 8.7.2
and 8.7.3 respectively. The numerous direct thermal or other
uses of geothermal energy are discussed in Section 8.7.4.
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 3.
2Meidav, T., S. Sanyal, and G. Facca. "An Update of World
Geothermal Energy Development." Geothermal Energy Magazine.
5(5): 30-34, May 1977.
3Howard, J.H. "Principal Conclusions of the Committee on
the Challenges of Modern Society Non-Electrical Applications
Project." Proceedings Second United Nations Symposium on the
Development and Use of Geothermal Resources.San Francisco, CA.
May 20-29, 1975.Washington, D.C.:U.S. Government Printing
Office. 1976. pp. 2127-2139.
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8.7.1 Electric Power Generation
There are essentially five conversion technologies for the
production of electricity from geothermal fluids:
dry steam system
flashed steam system
binary cycle system
hybrid flashed steam/binary cycle system
total flow system.
Features of each system are discussed in the following sections.
8.7.1.1 Dry Steam System
A simplified schematic for the production of electricity
from a geothermal dry steam resource is shown in Figure 8-9.
Dry steam systems are currently producing electricity on a
commercial scale in the United States, Italy, and Japan. At the
Geysers in Sonoma County, California, Pacific Gas and Electric
Company is producing over 500 MWe from a dry geothermal steam.
This represents the only commercial use of geothermal energy
for electricity generation in the United States. By 1985,
production at The Geysers is expected to increase to 1800-2130
MWe, comprising 50-60 percent of the estimated geothermal power
production in the U.S.1
The geothermal steam from production wells requires only
minor pretreatment prior to use. This pretreatment usually
xLa Mori, Phillip N. "Growth in Utilization of Hydrothermal
Geothermal Resources." Geothermal Resources Council, Transactions,
Vol. 1, May 1977. pp. 181-182.
-147-
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STEAM
STEAM
FROM
PRODUCTION
WELLS
t:
TURBINE
GENERATOR
COOLING
TOWER
DIRECT
CONTACT
CONDENSER
CONDENSATE
PUMP
T
CIRCULATING
WATER
PUMP
SLOWDOWN
PUMP
c
TO
REINJECTION
WELLS
Figure 8-9. Simplified Schematic of a Dry Steam Energy Con-
version System
Source: Ramachandran, G. et al. Economic Analyses of Geother-
mal Energy Development in California, 2 Vols.Stanford
Research Institute.Prepared for U.S. Energy Research
and Development Administration and California Energy
Resources Conservation and Development Commission.
Contract No. ERDA/SAN E(04-3)-115-P.A.108. May 1977.
p. 30.
-148-
-------
entails the removal of particulate matter and occasional slugs
of water. The cleaned steam is expanded in a conventional low-
pressure steam turbine which then powers a generator to produce
electricity. Although steam could be exhausted from the turbine
directly to the atmosphere, a condenser is normally employed
to increase turbine efficiency and avoid the condensation of
steam in the turbine. Either a direct contact condenser or a
surface condenser can be used to condense the exhaust steam.
In surface condensers, the coolant does not contact the vapor
or condensate: condensation occurs on a wall separating the
coolant and the vapor. Contact condensers usually cool the
vapor by spraying the coolant directly into the gas stream.
Contact condensers also act as scrubbers in removing vapors
which normally might not be condensed. Heat rejection systems
such as cooling towers provide cooling water for the condensers.1
To maximize the energy extraction of the power cycle and
s
to avoid the condensation of steam in the turbine, a vacuum is
maintained in the exhaust steam condensers. Noncondensable
gases including in-leakage air, which limit the vacuum that can
be maintained, are removed with gas ejectors: either multi-
stage steam jets or centrifugal exhausts are typically employed.2
Direct contact condensers are currently used in those dry
steam systems that condense turbine exhaust steam.3 Noncon-
densable gases removed with gas ejectors are simply released to
Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15', 1975, p. 32.
2Axtmann, R. C. "Emission Control of Gas Effluents from
Geothermal Power Plants." Environmental Letters 8(2): 135-146
(1975).
3 ibid.
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the atmosphere. At The Geysers, a program is planned in which
a ducting system will be installed on all existing units to
transfer the gases from the gas ejectors to the cooling towers.
Proposed air pollution control techniques to be applied at the
cooling towers are discussed in Section 8.7.3.I.1 Future gener-
ating units built at The Geysers will employ surface condensers
to condense turbine exhaust steam.2
No external makeup water is required for cooling at The
Geysers: all cooling water is supplied by condensed turbine
exhaust steam.3'1*
Current generating units at The Geysers are relatively
small; an average plant supplies 110 MWe electric power and
consists of two 55-MWe generators. About two million Ib/hr of
steam at 350°F and 100 psi enter the turbines at each plant.5
1 Resource Planning Associates, Inc. Western Energy Resources
and the Environment; Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May
1977, p. 79.
2Ramachandran, G., et al. Economic Analyses of Geothermal
Energy Development in California, 2 Vols.Stanford Research
Institute.Prepared for U.S. Energy Research and Development
Administration and California Energy Resources Conservation and
Development Commission. Contract No. ERDA/SAN E(04-3)-115-P.A.
108. May 1977 p. 41.
3Axtmann, R. C. "Emission Control of Gas Effluents from
Geothermal Power Plants." Environmental Letters 8(2): 135-146
(1975). p. 141.
''Resource Planning Associates, Inc., op.dt., p. 60.
*ibid., pp. 19-20.
-150-
-------
Plants larger than 100 MWe are not anticipated.1'2 The overall
plant efficiency for power production from geothennal steam is
approximately 14 to 16 percent, compared to 32 to 34 percent
for nuclear power production and 36 to 40 percent for production
from fossil fuels.3
8.7.1.2 Flashed Steam System
A simplified schematic for the production of electricity
from a geothennal hot water or liquid-dominated resource is
shown in Figure 8-10. Plants employing the flashed steam
process are in operation or under construction in New Zealand,
Mexico, Japan, the Philippines, Central America, and Iceland.
The largest of these facilities is located at Wairakei, New
Zealand, with an installed power generating capacity of 190 MWe.
A flashed steam plant at Cerro Prieto, Mexico, has an electric
power production capacity of 75 MWg.1* No commercial flashed
steam plants have been built in the United States.
If the pressure of a liquid-dominated geothennal fluid
is not maintained as the fluid is withdrawn from a well, the
xThe Futures Group. A Technology Assessment of Geothermal
Energy Resource Development^Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, pp. 53, 56.
2Larger plants must be supplied with steam from wells
located greater distances from the site of power generation.
As the plant size increases, the increased costs of the piping
network become.more important than economies of scale associated
with larger units.
3Uranesh, G. and J. D. Musick, Jr. "Geothermal Resources:
Water and Other Conflicts Encountered by the Developer." Geo-
thermal Resources Development Institute. Rocky Mountain Mineral
Law Foundation, Boulder, Colorado.January 27-28, 1977, p. 6-10,
^Muffler, L. J. P. "Summary of Section I: Present Status
of Resources Development." Proceedings Second United Nations
Symposium on the Development and Use of Geothermal Resources.
San Francisco, CA, May 20-29, 1975.Washington, D.C.:DTsT
Government Printing Office, 1976, pp. xxxiii-xlv.
-151-
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TURBINE-GENERATOR
STEAM
HIGH-PRESSURE
FLASH VESSEL ,^-x
LOW-PRESSURE
FLASH-VESSEL
COOLING
TOWER
BRINE/
CONDENSATE
JBRINE/
CONOENSATE
PUMP
DIRECT
CONTACT
CONDENSER
CONDENSATE
PUMP
MAKEUP.
WATER
CIRCULATING
WATER PUMP
BLOWDOWN
HOT WATER/BRINE TO
FROM REINJECTION
PRODUCTION WELLS
WELLS
Figure 8-10.
Simplified Schematic of a Two-Stage Flashed Steam
Energy Conversion System
Source: Ramachandran, G. et al. Economic Analyses of Geother-
mal Energy Development in California, 2 Vols.Stanford
Research Institute.Prepared for U.S. Energy Research
and Development Administration and California Energy
Resources Conservation and Development Commission.
Contract No. ERDA/SAN E(04-3)-115-P.A.108. May 1977.
p. 32.
-152-
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fluid may issue at the surface as a two-phase mixture of steam
and hot water (or brine). Additional quantities of steam are
produced in a separator by flashing the fluid at a reduced
pressure and separating the two phases. After the removal of
particulates, the steam is expanded in a conventional low-
pressure steam turbine which then powers a generator to produce
electricity. The remainder of the power cycle is similar to
the previously discussed cycle for producing electricity from
dry steam.1
It is usually desirable to flash the residual liquid a
second time, using the secondary steam in lower stages of a
turbine. This process option is demonstrated in the flashed
steam system illustrated in Figure 8-10. Theoretically, energy
extraction is maximized by flashing the residual fluid an
infinite number of times. However, more than two flash stages
appear to be impractical.2
For fluids high in dissolved solids or noncondensable
gases, flashed steam plants may be impractical. Flashing can
result in the deposition of solids, while the presence of
noncondensables reduces the net power production from steam
turbines.3 Carryover of salts into the steam can cause
:The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, pp. 33-34.
2The Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera, New Mexico, and Raft River, Idaho - Case Studies.
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976, p. 20.
3Bloomster, C. H. and C. A. Knutsen. The Economics of
Geothermal Electricity Generation from Hydrothermal Resources.
Battelle Pacific Northwest Laboratories. BNWL-19S9.Richland,
Washington: 1976, pp. 33-34.
-153-
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corrosion, erosion, or scaling of turbine components.1 A
flashed steam plant may also be unattractive for power production
from intermediate-temperature geothermal fluids. The steam yield
from such fluids is low, and the consequent increase in produc-
tion well costs may be prohibitive.2
8.7.1.3 Binary Cycle System
A schematic of a simple binary cycle system is reproduced
in Figure 8-11. Only two binary cycle geothermal power plants
are in use anywhere in the world: pilot plants of 3.8 MWe and
0.75 MWe are operating in Japan and the Soviet Union respectively.
Power from the Soviet plant is produced by energy extracted
from an 80°C geothermal fluid.3'1*
San Diego Gas and Electric Company plans to build a 45 MWe
(net) binary cycle demonstration plant at Heber, California.
Plant start-up is expected in 1980. The Heber demonstration
will have some applicability to roughly 80 percent of the
identified liquid-dominated resources in the United States.5
Austin, A. L. and A. W. Lundberg. "Electric Power Genera-
tion from Geothermal Hot Water Deposits." Mechanical Engineering
97(12): 18-25, December 1975.
2Sacarto, D. M. State Policies for Geothermal Development
NSF/RA-760230. Funded through grant by National Science
Foundation. Denver, Colorado: National Conference of State
Legislatures, 1976, p. 27.
3Resource Planning Associates, Inc. Western Energy Resources
and the Environment; Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C. : U.S.' Environmental Protection Agency, May
1977, p. 18.
"•Austin, A. L. and A. W. Lundberg, op.cit.
5Lombard, G. L. "Heber Geothermal Demonstration Plant."
Geothermal Resources Council. Transactions. Vol. 1, May 1977,
pp. 195-196.
-154-
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TURBINE-GENERATOR
HOT WATER/
BRINE PUMP
COOLING
TOWER
WORKING
FLUID
HEAT
EXCHANGER
MAIN
FEED
PUMP
LOW-PRESSURE
FEED PUMP
CIRCULATING
WATER PUMP
BLOWOOWN
PUMP
HOT WATER/BRINE TO
FROM REINJECTION
PRODUCTION WELLS
WELLS
Figure 8-11. A Schematic Diagram of a Binary Cycle Energy Con-
version System
Source: Ramachandran, G. et al. Economic Analyses of Geother-
mal Energy Development in California 2 Vols. Stan-
ford Research Institute.Prepared for U.S. Energy
Research and Development Administration and California
Energy Resources Conservation and Development Com-
mission. Contract No. ERDA/SAN E(04-3)-115-P.A.108.
May 1977. p. 33.
-155-
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Magma Power Company is constructing an 11.2 MVfe (net)
"dual binary cycle" power plant at East Mesa in Imperial Valley,
California. Heat is recovered from a high-temperature geothermal
fluid by two binary cycle systems. Magma anticipates start-up
of the new plant in the spring of 1978.l
In the binary process, thermal energy in a hot water (or
brine) geothermal resource is used to heat a second fluid having
a lower boiling point. Typically, a conventional surface heat
exchanger is employed to transfer heat from the geothermal fluid
to the "working" fluid. More recently, the use of direct
contact heat exchangers has been proposed. The direct contact
exchanger may reduce the buildup of scale on heat exchanger
surfaces and may reduce capital costs. Total power costs may
be similar.2'3'1*
After heat exchange, the vaporized "working" fluid is
expanded through a turbine to produce electricity. The expanded
fluid is then condensed and pumped up to its initial pressure
for recycle through the system. 5
'Hinrichs, T. C. and H. W. Falk, Jr. "The East Mesa
'Megamax Process1 Power Generation Plant." Gepthermal Resources
Council. Transactions. Vol. 1, May 1977, pp. 141-142.
2The Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera, New Mexico, and Raft River, Idaho - Case Studies"
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976. p. 15.
3Sheinbaum, I. "Power Production from High Temperature
Geothermal Waters." Geothermal Energy Magazine 4(10): 17-24,
October 1976.
**Harris, J. S., et al. "Conceptual Design and Evaluation
of Geothermal-Driven 50 MWe Power Plants." Geothermal Resources
Council. Transactions. Vol. 1, May 1977, pp. 195-196.
5The Ben Holt Company and Procon, Inc., op.cat., p. 25.
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Light aliphatic hydrocarbons (such as propane, isobutane
and isopentane) appear to be the best candidate working fluids
for most binary cycles using a surface heat exchanger. The
freons may also be used. Other suggested working fluids are
ammonia, sulfur dioxide, carbon dioxide, and light aliphatic
olefins. None appear to offer advantages over the light ali-
phatic hydrocarbons.l
The geothermal fluid supplied to a binary cycle power plant
may be available as a one-phase brine or as a two-phase mixture
of brine and steam. It is usually more desirable to supply the
fluid as a one-phase brine; the one-phase brine entails fewer
scaling problems2 and provides more efficient heat exchange.
The brine may be maintained as a one-phase fluid by downhole
pumps. (These downhole pumps are relatively underdeveloped.)
The binary cycle system has several attractive features
compared to flashed steam systems. First, the binary cycle
system is potentially more efficient in recovering heat from
geothermal fluids whose temperatures are less than 400°F at the
wellhead.3 Second, the binary cycle avoids some of the scaling
problems associated with the flashing of geothermal brines. "*
:The Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power'Generationat Heber, TaTifp'rnia,
Valles Caldera, New Mexico, and""Raft" RlveiT, Idaho - Case Studies"!
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976, p. 26.
2Cortez, D. H., Ben Holt, and A. J. L. Hutchinson. "Advanced
Binary Cycles for Geothermal Power Production." Energy Sources.
Vol. 1, No. 1, 1973. pp. 81, 92.
3The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 34.
"Cortez, D. H., Ben Holt, and A. J. L. Hutchinson, op.cit.,
pp. 80, 86.
-157-
-------
Finally, the power production of binary cycle systems is not
impaired by noncondensable gases contained in the geothertnal
fluid.1
8.7.1.4 Hybrid Flashed Steam/Binary Cycle System
Hybrid systems employ elements of both flashed steam and
binary cycle technologies. Since May 1976, San Diego Gas and
Electric has been operating a "geothermal loop experimental
facility" employing one hybrid cycle scheme. The experimental
facility is sized to produce 10 MWe electric power using a
hybrid cycle; initial operating experience has been obtained
without a turbine/generator installation.2
The experimental facility is located at Niland, California,
and uses the high-temperature high-salinity brine resource
of the Salton Sea Geothermal Anomaly. The primary design and
functional intent of the hybrid cycle is to minimize scaling
in the brine/working fluid heat exchangers. The hybrid cycle
at the Niland test facility consists of: flashing the brine at
four successively lower pressures, scrubbing particulates from
the flashed steam, and vaporizing the working fluid by condensing
the flashed steam in surface heat exchangers. The vaporized
working fluid can then be expanded through a turbine to generate
electricity. Major problems experienced to date have been scale
deposition and injection well plugging. The brine piping network
1 Bloomster, C. H. and C. A. Knutsen. The Economics of
Geothermal Electricity Generation from Hydrothermal Resources.
Battelle Pacific Northwest Laboratories. BNWL-1989.Richland,
Washington, 1976, p. 34.
2Jacobson, W. 0. "Recent Operational Experience at the
SDG&E/ERDA Niland Geothermal Loop Experimental Facility."
Geothermal Resources Council, Transactions, Vol. 1, May 1977,
pp. 153-155.
-158-
-------
must be continuously cleaned of scale. Continuous operation is
limited by scale accumulation at the reinjection pumps.1'2
An alternate hybrid cycle has been described by Holt/
Procon.3 In this hybrid process, part of the geothermal brine
is flashed into steam. The flashed steam is then used to drive
a conventional steam turbine. The residual heat in the brine
is then transferred to a working fluid. The vaporized working
fluid is used to drive a second turbine. This process appears
to be especially susceptible to scaling problems in the brine/
working fluid heat exchanger.
8.7.1.5 Total Flow System
Several novel heat engines have been proposed for directly
converting the thermal and kinetic energy of a two-phase
geothermal fluid into shaft work without phase separation.
Energy is recovered by the two-phase expansion of the geothermal
fluid. Classes of expanders developed for total flow applica-
tions are shown in Table 8-47. Operating characteristics and
descriptions of total flow expanders1 are often proprietary. "*• 5
1 Jacobson, W. 0. "Recent Operational Experience at the
SDG&E/ERDA Niland Geothermal Loop Experimental Facility."
Geothermal Resources Council, Transactions, Vol. 1, May 1977,
pp. 153-155.
2The Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera, New Mexico, and Raft River, Idaho - Case Studies"!
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976, p. 15.
f
3 Ibid.
* Austin, A. L. and A. W. Lundberg. "Electric Power Generation
from Geothermal Hot Water Deposits.11 Mechanical Engineering
97(12): 18-25, December 1975.
5The Futures Group. A Technology Assessment of Geothermal
Energy Resource Development"! Prepared for National Science
Foundation, Contract No. C-836. Glastonbury, Connecticut: The
Futures Group, April 15, 1975, p. 34.
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TABLE 8-47 .
CLASSES OF EXPANDERS DEVELOPED OR CONSIDERED FOR
TOTAL FLOW APPLICATIONS
Class
Examples
Impulse/reaction machines
Axial flow
Radial inflow
Radial outflow
Curtls/Rateau steam turbine
Francis turbine
Hero's turbine
Bladeless impuse or reaction drag
turbine
Positive displacement machines
Helical screw expander
Rotating oscillating vane machine
Impulse machines
Tangential flow
Axial flow
Pelton wheel
Re-entry turbine
DeLaval turbine
Curtis turbine
Source:
Austin, A. L. and A. W. Lundberg. "Electric Power Generation from
Geothermal Hot Water Deposits." Mechanical Engineering 97(12);
18-25, December 1975.
-160-
-------
One proposed design uses a helical screw which rotates as the
fluid expands along its axis.1 Other designs employ principles
applied in waterwheels. While total flow expanders theoretically
recover more energy than other systems, little operating experi-
ence has been attained. Potential problems are associated with
scaling, corrosion, and erosion of metal parts.2
8.7.2 Input Requirements
Input requirements and outputs of electric power generation
are associated with the electric power plant and the reinjection
well piping network. Manpower, materials and equipment, finances,
water, land, and ancillary energy requirements for electric
power generation and reinjection of spent geothermal fluids
are discussed in the following sections.
8.7.2.1 Manpower
Manpower requirements for the construction, operation, and
maintenance of a reinjection well piping network and geothermal
power plant have been estimated by Bechtel Corporation for the
Federal Energy Administration. Bechtel1s estimates of construc-
tion manpower include manpower requirements during the design,
Austin, A. L, "Total Flow Concept for Geothermal."
Proceedings of the Conference on Research for the Development
of Geothermal Energy Resources"!NSF-RA-N-74-159.Organized
by Jet Propulsion Laboratory, California Institute of Technology,
Pasadena, California, September 23-25, 1974, pp. 186-194.
2The Ben'Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera, New Mexico, and Raft River. Idaho - Case Studies.
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976, p. 15.
3Federal Energy Administration, Interagency Task Force on
Geothermal Energy. Project Independence Blueprint, Final Task
Force Report: Geothermal Energy.Washington, D.C.:U.S.
Government Printing Office, 1974, pp. D-3 to D-7.
-161-
-------
procurement, construction, testing, and start-up of the power
plant and piping network. Construction manpower for the rein-
jection well piping network previously defined in Section 8.4.2
is reported in Table 48. Estimates reported herein are simply
extrapolated from those reported by Bechtel.
Construction manpower for the geothermal power plant are
reported in Table 8-49. Manpower requirements for the construc-
tion of a hot water or brine power plant are assumed to be 40
percent greater than the manpower requirements for construction
of a dry-steam plant.l Manpower requirements for construction
of a power plant using a fluid from a hot rock system are probably
similar to the manpower requirements for a brine power plant.
Personnel required for the operation and maintenance of
the reinjection piping network are summarized in Table 8-50.
Estimates of the personnel required to operate and maintain a
100 MWe dry-steam power plant are presented in Table 8-51. Man-
power estimates for the operation and maintenance of a 100 MWe
brine power plant are presented in Table 8-52, as estimated by
Holt/Procon.2'3
8.7.2.2 Materials and Equipment
Construction of the reinjection piping network and power
plant requires heavy equipment to: transport and handle pipe,
1Federal Energy Administration, Interagency Task Force on
Geothermal Energy. Project Independence Blueprint, Final Task
Force Report: Geothermal Energy!Washington, D.C.:U.S.
Government Printing Office, 19/4, p. D-3.
2The Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera, New Mexico, and Raft River. Idaho - Case Studies.
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976, p. 102.
3Data reported by Holt/Procon describe a 50 MWe plant; data
for a 100 MWe plant are assumed to be double those of 50 MWe plant.
-162-
-------
TABLE 8-48.
MANPOWER REQUIRED TO CONSTRUCT A REINJECTION PIPING NETWORK ASSOCIATED
WITH A 100 MWe POWER PLANT
Manpower, total man-years
Hot water resource Hot water resource Hot rock resource Steam resource0
Binary Direct steam Binary Direct
Personnel Description fluid cycle flashing cycle fluid cycle steam cycle
Design
Mechanical engineer
Civil engineer
Draftsman3
«
Draftsman
Route surveyor*
Construction
Civil engineer
Foreman
Pipefitterb
Welderb
Carpenter
Concrete worker
Dozer operator
Truck driver
Crane operator
Insulation installer
Inspector (construction)
Inspector (nondestruc-
tive testing)5
TOTAL
aBased on 4 -month design program.
Based on 8-month construction program.
0.9
0.4
0.4
0.4
1.6
0.9
1.8
3.9
2.6
1.3
2.6
1.3
2.6
1.3
0.6
0.7
0.8
24
Source: Federal Energy Administration. Interagency Task
Independence Blueprint Final Task Force Report:
1.0
0.5
0.5
0.5
1.8
1.0
2.0
4.2
2.8
1.4
2.8
1.4
2.8
1.4
0.7
0.8
0.9
27
C0nly
0.1
0.1
0.1
0.1
0.2
0.1
0.3
0.4
0.3
0.2
0.3
0.2
0.3
0.2
0.1
0.1
0.1 ^
3 -vl
one re-injection well required.
Force on Geothermal Energy. Project
Geo thermal Energy. Washington, D.C.
U.S. Government Printing Office. 1974. p. D-6.
-------
TABLE 8-42.
MANPOWER REQUIRED TO CONSTRUCT A 100 MWe GEOTHER-
MAL POWER PLANT3
Manpower ,
Hot water resource
Personnel Description
Structural Engineer
Mechanical Engineer
Civil Engineer
Electrical Engineer
Corrosion Engineer
Architect
Draftsman (Designer Quality)
Draftsman
Topographical Surveyor
Purchasing Agent
Equipment Inspector
Corrosion Engineer
Civil Engineer (Construction)
Mechanical Engineer
Electrical Engineer
Surveyor (Construction Control)
Inspector (Construction)
Superintendent
Asst. Superintendent (Contraction)
Foreman
Electrician
Pipe Fitter
Welder
Millwright
Iron-Worker
Concrete Worker
Sheetmetal Worker
Carpenter
Plumber
Insulation Installer
Tile-Setter
Painter
Instrument Technician
Machinist
Rigger
Truck Driver
Crane Operator
Timekeeper
Warehouseman
Pile-Driver
Laborer
TOTAL
Based on 1.5 year design schedule.
1st yr.
1.4
3.5
1.4
2.1
0.2
0.4
2.8
8.1
2.3
0.4
0.7
0.1
1.4
0.7
1.4
2.8
2.1
0.7
0.7
3.5
2.8
-
2.8
-
2.1
1.1
-
7.0
-
-
-
-
-
-
1.1
3.5
2.1
l.l
1.1
2.8
10.5
75
3 year
2nd yr.
0.7
1.8
0.7
1.1
-
0.1
1.4
2.3
-
0.4
0.7
-
1.4
0.7
1.4
2.8
2.1
0.7
0.7
4.2
4.2
-
5.6
4.2
4.2
1.1
2.1
7.0
-
1.4
-
2.1
1.1
1.4
2.8
3.5
2.8
1.1
2.1
-
14.0
84
construction
Source: Federal Energy Administration. Interagency Task
Independence 31ueorinc. Final Task Force Report
3rd yr.
-
-
-
-
-
-
-
-
-
-
-
0.1
1.4
0.7
1.4
0.7
2.1
0.7
0.7
3.5
4.2
7.0
4.2
2.8
2.8
4.9
4.2
2.8
2.8
2.8
1.1
2.8
2.1
1.4
2.1
2.8
2.1
l.l
1.4
-
7.0
74
schedule.
man-years
Dry sti
1st yr. 1
1.0
2.5
1.0
1.5
0.1
0.3
2.0
5.8
1.7
0.3
0.5
0.1
1.0
0.5
1.0
2.0
1.5
0.5
0.5
2.5
2.0
-
2.0
-
1.5
0.7
-'
5-0
-
-
-
-
-
-
0.7
2.5
.1.5
'o.S
0.5
2.0
2Li
53
aam resource
2nd yr.
0.5
1.3
0.5
0.8
-
0.1
1.0
2.0
-
0.3
0.5
-
1.0
0.5
1.0
2.0
1.5
0.5
0.5
3.0
3.0
-
4.0
3.0
3.0
0.7
1.5
5.0
-
1.0
-
1.5
0.7
1.0
2.0
2.5
2.0
0.5
1.5
-
10.0
60
3rd yr.
-.
-
-
-
-
-
-
-
-
-
-
0.1
1.0
0.5
1.0
0.5
1.5
0.5
0.5
2.5
3.0
5.0
3.0
2.0
2.0
3.5
3.0
2.0
2.0
2.0
0.7
2.0
1.5
1.0
1.5
2.0
1.5
0.5
1.0
-
1^0
52
Force on Geotheraal Energy. Project
: Geo thermal Energy. Washington. D.C. :
avernment Printing Office,
-164-
-------
TABLE 8-50. MANPOWER REQUIRED TO OPERATE AND MAINTAIN A RE-INJECTION PIPING NET-
WORK ASSOCIATED WITH A 100 MWe POWER PLANT
Personnel Description
Manpower, average man-years per year
Hot water resource
Binary
fluid cycle
Hot water resource
Direct steam
flashing cycle
Hot rock resource
Binary
fluid cycle
Steam resource
Direct
steam cycle
Operation
Field Operator
1.3
1.4
0.2
ui
i
Routine Maintenance
Foreman
Pipefitter
Welder
Insulation Installer
Crane Operator
TOTAL
0.1
0.3
0.1
0.3
0.1
2.2
0.1
0.3
0.1
0.3
0.1
2.3
M)
M)
00
%o
%o
0.3 'UKl
Source: Federal Energy Administration. Interagency Task Force on Geothermal Energy. Project Indepen-
pendence Blueprint Final Task Force Report; Geothermal Energy. Washington, D.C.: U.S.
Government Printing Office. 1974. p. D-7.
-------
TABLE 8-51. MANPOWER REQUIRED TO OPERATE AND MAINTAIN A 100
MWe GEOTHERMAL STEAM POWER PLANT
Personnel Description
Manpower, average man-years
per year
Operation
Plant superintendent
Shift foreman
Plant operator
0.5
1.5
4.5
Routine Maintenance
Mechanical engineer
(turbine specialist)
Corrosion engineer
Instrument technician
Foreman
Millwright
Machinist
Pipefitter
Welder
Electrician
Insulation installer
Painter
Rigger
Crane Operator
Laborer
TOTAL
J 0.1
0.3
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
< 0.1
0.1
8
Source: Federal Energy Administration. Interagency Task Force
on Geothermal Energy. Project Independence Blueprint
Final Task Force Report: Geothermal Energy. Wash-
ington, D.C.: U.S. Government Printing Office. 1974.
p. D-7.
-166-
-------
TABLE 8-52 . MANPOWER REQUIRED TO OPERATE AND MAINTAIN A 100
HOT WATER OR BRINE POWER PLANT
Personnel Description Required Number of Personnel
Superintendent 1
Office manager 1
Electrician
Instrument specialist
Mechanic
Laborer 2
Operator 18_
TOTAL 26
Source: The Ben Holt Company and Procon, Inc. Energy Con-
version and Economics for Geothermal Power Generation
at Heber, California, Valles Caldera, New Mexico, and'
Raft River. Idaho - Case Studies.Prepared for Elec-
tric Power Research Institute, EPRI ER-301, Research
Project 580, Topical Report 2, November 1976. p.102.
-------
prepare pipeline corridors, prepare the site of the power plant,
prepare transmission line corridors, install power plant equip-
ment, and construct related surface facilities. None of this
equipment is permanently committed to the reinjection piping
network and power plant.
Steel in the piping network is the largest material require-
ment of the reinjection system. Based on the previous discussion
in Section 8.6.2.2, steel used in the reinjection piping network
is estimated as the following:
Hot water resource 2200-2400 tons
Hot rock resource 360 tons
Steam resource1 40 tons.
Major equipment installed in geothermal power plants include:
heat exchangers, turbine-generators and electrical gear, pumps,
cooling tower, flash drums, accumulators, and scrubbers.
8.7.2.3 Economics
Milora and Tester2 have developed capital costs estimates
for binary cycle and flashed steam cycle power plants utilizing
a 150°C geothermal fluid. Capital costs have also been developed
for a binary cycle power plant utilizing a 250°C geothermal
fluid produced from a hot rock geothermal development. These
costs estimates are presented in Table 8-53, and are among the
most recent available. Capital costs for the reinjection
one reinjection well is required.
2Milora, S. L. and J. W. Tester. Geothermal Energy as a
Source of Electric Power: Thenaodynamic and Economic Design
Criteria.—Cambridge, Massachusetts: The MIT Press, 1976,
pp. 105-106.
-168-
-------
TABLE 8-53. ESTIMATED CAPITAL COSTS OF POWER PLANT (AND ASSOCIATED REINJECTION
PIPING NETWORK) PRODUCING 100 MWe ELECTRIC POWER
a
Geothermal Resource Development
Cost Component
Hot water @150°C
Binary-fluid
cycle
Hot water @150°C
Flashed steam
cycle
Hot rock: water @250°C
Binary-fluid
cycle
Power plant
Turbine
Generator
$ 308,000 $41,700,000 $ 205,000
1,130,000
Pumps 740 , 000
Turbine drive 87,600
Heat exchanger 11,000,000
Flashing
tanks and cyclones
Condenser/desuperheater 7,280,000
1,130,000 1,130,000
250,000 255»°00
10,000
3,840,000
200,000
500,000 8,770,000
Total purchased equipment 20,500,000 43,800,000 14,200,000
Total power plant capital $56,800,000 $12
investment $568/kwe $1
1,000,000 $39,400,000
,210/kwe $394/kwe
Reinjection piping network
$ 9,600,000
$10,400,000
$ 1,500,000
1976 Dollars
Source: Milora, S. L. and J. W. Tester. Geothermal Energy as a Source of Electric Power;
Thermodynamic and Economic Design Criteria. Cambridge, Massachusetts: the MIT
Press, 1976.
-------
piping network have been estimated by the method outlined in
Section 8.5.2.3; these costs are also summarized in Table 8-53.
The costs for the hot water power plants confirm trends reported
by Holt/Procon:1 binary cycle systems are more efficient and
economic than flashed steam systems at lower fluid temperatures.
Lower capital costs per kilowatt generating capacity are expected
for the flashed steam cycle at higher geothermal fluid tempera-
tures .
Total capital and annual costs for the production of
electricity from hot brines and hot rock are summarized in
Table 8-54. These cost estimates are subject to change as the
technologies are further developed and ultimately demonstrated.
Costs for the production of electricity from three low salinity,
water-dominated resources are reported in Table 8-55, as
estimated by Bloomster and Knutsen.2 Data in Table 8-55
illustrate the economies resulting from the increased efficiency
of energy extraction at higher temperatures. At high tempera-
tures , the flashed steam cycle is more economic than the binary
cycle.
Capital costs for new power generation units at The Geysers
dry steam field amount to about $170/kw (in 1976 dollars).3
xThe Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera. New Mexico, and Raft River, Idaho - Case Studies"!
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976.
2Bloomster, C. H. and C. A. Knutsen. The Economics of
Geothermal Electricity Generation from Hydrothermal Resources.
Battelle Pacific Northwest Laboratories. BNWL-1989.Richland,
Washington, 1976. Tables 2, 7.
3Greider, B. "Status of Economics and Financing of Geothermal
Energy Power Production." Proceedings Second United Nations
Symposium on the Development and Use of Geothermal Resources.
San Francisco, CA, May 20-29, 1975.Washington, D.C.:UTST
Government Printing Office, 1976, pp. 2305-2314.
-170-
-------
TABLE 8-54. COST SUMMARY FOR THE PRODUCTION OF ELECTRICITY FROM 100 MWe HOT WATER
POWER PLANTSa
Geo thermal Resources Development
Hot water @150°C
Cost Components
Capital Costs
Exploration
WellsC
Well-head production system
Q "*
Power plant
Reinjection piping network
TOTAL
Annual Costs
Fixed charges
o
Operating and maintenance
Power generating cost at busbar
Costs in 1976 dollars.
Scaled from data in Table 8-14 and
CFrom Table 8-25.
From Table 8-44.
Binary-fluid
cycle
$ 7,200,000
43,300,000
12,000,000
56,800,000
9,600,000
$129,000,000
$ 21,900,000
1,000,000
3.1<7kwh
escalated to 1976
Source: Milora, S. L. and J. W. Tester. Geothermal
Thernvodynamic and Economic
Design Criteria.
Hot water @150°C Hot
Flashed steam
cycle
$ 7,200,000
47,300,000
13,000,000
121,000,000
10,400,000
$199,000,000
$ 33,800,000
1,000,000
4 . 7c/kwh
6From Table 8-53.
$17% per year.
From Milora and Tester.
Based on load factor of
ates 7,446 hr/year.
rock: water @250°C
Binary-fluid
cycle
$ 7,200,000
13,000,000
1,800,000
39,400,000
1,500,000
$62,900,000
$10,700,000
1,000,000
1.6c/kwh
85%; plant oper-
Energy as a Source of Electric Power:
Cambridge, Massachusetts:
the MIT Press,
1976.
-------
TABLE 8-55. COSTS FOR ELECTRICITY GENERATED FROM THREE REPRESENTATIVE HOT WATER
RESERVOIRS21
1
I-*
•-4
to
1
Development
Technology
1. Two stage
flashed steam
2. Binary cycle
3. Binary cycle
4. Binary cycle
Wellhead
Temperature, °C
250
250
200
150
Powerplant
Gross
55
55
55
55
size, MWe
Net
53.0
46.1
44.5
45.9
Powerplant
Capital Cost
$291/kw
$329/kw
$335/kw
$375/kw
Total Cost of
Generating Electricity
1.7c/kwh
2.0c/kwh
2.8c/kwh
8.5c/kwh
1976 conditions.
Source: Greider, R. "Economic Considerations for Geothermal Exploration in the Western United States,"
Bulletin, Geothermal Resources Council, Davis, California, May/June 1974. Tables 2, 7.
-------
Stanford Research Institute has estimated that the total capital
investment at a dry steam field ranges from $200-280 per kilowatt
of capacity. The busbar price of electricity from a dry steam
power plant has been reported as 20/kwh.1
8.7.2.4 Water
By far the largest use of water at a geothermal power plant
is cooling. This requirement varies with the power production
method, the cooling method, and the potential requirement2
for reinjection of a volume of fluid equal to the volume of the
extracted fluid.
Anglin3 has estimated the cooling water requirements for
50 MWe geothermal brine power plants located at Heber, California.
These data are summarized below, as scaled to a facility size
of 100 MWe:
One-stage flashed steam
Two-stage flashed steam
Binary cycle
Water
Evaporated
Slowdown
10,300
9,500
10,000
acre-ft/year
3,400
3,200
3,300
Total
Make-up
13,700
12,700
13,300
1Romachandran, G., et al. Economic Analyses of Geothermal
Energy Development in California^2 Vols.Stanford Research
Institute.Prepared for U.S. Energy Research and Development
Administration and California Energy Resources Conservation and
Development Commission. Contract No. ERDA/SAN E(04-3)-115-P.A.
108. May 1977. pp. 74-75.
2Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at Heber, Imperial County, California:
Water and Land Use Issues.Working Paper No. 2, Jet Propulsion
Laboratory, California Institute of Technology, December 14, 1976,
p. 22.
-173-
-------
Similar cooling water requirements are expected for systems
using a geothermal fluid produced in a hot rock development.
The above tabulated data describe the typical use of wet-
cooling towers.
As discussed earlier, condensed turbine exhaust from dry
steam and flashed steam systems can completely satisfy make-up
requirements for cooling water. The above make-up requirements
for flashed steam systems exist only when complete reinjection
of the geothermal fluid is required.
8.7.2.5 Land
From discussions with drillers, Anglin1 has.concluded that
about one-half acre per reinjection well is permanently committed
to the geothermal fluid reinjection network. Included in the
above estimate are land areas required for the piping network,
service roads, pumps, and the like. Anglin has also estimated
land requirements for power generation and transmission facilities
to be 8 MWe/acre for a flashed steam plant and 11 MWe/acre for
a binary plant. At The Geysers, land requirements have been
reported as 27.5 MWe/acre.2 Based on the above estimates and
the required number of reinjection wells for a 100 MWe complex,
the following areas are assumed to be permanently committed to
power production facilities and the reinjection piping network:
1Anglin, R. L. Potential Power Generation Utilizing the
Geothermal Resource at~Heber. Imperial County, California:
Water and Land Use Issues. Working Paper No. 2, Jet Propulsion
Laboratory,California Institute of Technology, December 14, 1976.
2The topography of the region severely constrains plant
layout design at The Geysers.
-174-
-------
Hot water resource 31-37 acres
Hot rock resource 15 acres
Steam resource 4 acres
8.7.2.6 Ancillary Energy
Holt/Procon1 has indicated that about 5-20 percent of the
gross output from brine power plants is required for plant use,
including the pumping of geothermal brine. This is energy
supplied from inside the plant boundaries and strictly defined
is not ancillary energy. Hence, the geothermal power generation
facilities have no ancillary energy requirements.
8.7.3 Outputs
Outputs associated with the generation of electricity from
geothermal resources are discussed in the following sections.
These outputs include: air emissions, water effluents, solid
wastes, noise pollution, occupational health and safety hazards,
and odors.
8.7.3.1 Air Emissions
Air emissions from geothermal power generation are chiefly
emissions of noncondensable gases from gas ejectors, and noncon-
densable gases and particulates from cooling towers (if direct
contact condensers are used). Only emissions from The Geysers
have been quantified; likely emissions from brine power plants
are discussed qualitatively. Data on emissions from brine plants
will not be available until brine plants are built in the U.S.
xThe Ben Holt Company and Procon, Inc. Energy Conversion
and Economics for Geothermal Power Generation at Heber, California,
Valles Caldera, New Mexico, and Raft River, Idaho - Case Studies.
Prepared for Electric Power Research Institute, EPRI ER-301,
Research Project 580, Topical Report 2, November 1976.
-175-
-------
Currently, power generating units at The Geysers emit air
pollutants from two sources: gas ejectors and cooling towers.
Estimates of the uncontrolled release of pollutants from these
sources are shown in Table 8-56, as measured by Pacific Gas and
Electric Company.1
About 96 percent of the nitrogen and essentially all of the
oxygen present in the ejector off-gas originate from air dissolved
into the cooling waters in the cooling towers, and air that leaks
into the subatmospheric pressure portions of the power generating
equipment. Trace amounts of radon are also present in the ejector
off-gas.2 The other gases were part of the geothermal fluids.
Two other groups of elements have been detected in trace
amounts. Cne of these groups includes certain elements normally
found in soil. This group includes silicon, aluminum, iron,
calcium, sodium, magnesium, titantium, and strontium, which
are emitted in the cooling tower drift in quantities less than
one Ib/day each. The other group of elements includes lead,
copper, chromium, manganese, nickel, and zinc. These five metals
may originate from the rock in the'steam field or may be eroded
from the piping and valves of the steam transportation network.
These elements are emitted in the cooling tower drift in
quantities less than 0.2 Ib/day each.3
Pollution control strategies are primarily designed to con-
trol hydrogen sulfide emissions. The current abatement program
at The Geysers includes plans to install a ducting system on
Griffin, D. P., Jr., H. K. McCluer, and R. 0. Dean.
"Emissions of Noncondensible Gases and Solid Materials from the
Power Generating Units at The Geysers Power Plant." Report
7485.16-74. Pacific Gas and Electric Company, Department of
Engineering Research. July 30, 1974. 13 pp.
2
Ibid.
3 Ibid.
-•Lie-
-------
TABLE 8-56. UNCONTROLLED EMISSIONS OF NONCONDENSABLE GASES AND SOLID MATERIALS
FROM THE POWER GENERATING UNITS AT THE GEYSERS POWER PLANT3
Range of Concentrations, by Vol.
Source
Ejector off-gas
Cooling tower exhaust
Cooling tower drift
Constituent
Carbon dioxide
Hydrogens sulflde
Methane
Oxygen
Nitrogen
Hydrogen
Hydrogen sulflde
Ammonia
Carbon dioxide
Arsenic
Boron
Mercury
Low
22 . 6%
0.52%
2.577.
1.237.
5. 8X
8.2%
--
--
--
_.
--
--
High
63.6%
1 . 607.
13.2%
15. 4%
50.1%
21.7%
--
--
--
__
--
--
Average Concentrations
by Vol.
41.7%
1.08%
7.2%
8.0%
28.1%
13.9%
5. 1 ppm
12 . 2 ppm
5.06 ppm
.-
--
--
by Wt.
59.97.
1.27.
3.8%
8.4%
25.8%
0.9%
--
--
--
.059 ppro
129 ppm
.0037 ppm
Mass Flow
5240 Ib/hr
105 Ib/hr
333 Ib/hr
735 Ib/hr
2260 Ib/hr
79 Ib/hr
275 Ib/hr
332 Ib/hr
254 Ib/hr
.0096 Ib/d
21 Ib/d
.00060 Ib/d
Scaled to basis of 100 HW(> generating capacity.
bDrift rate of .15 percent by weight of the cooling water flowing through tower, equal to 162,000 Ib/d.
Source.- Griffin, D. P., Jr., It. K. McCluer, and R. 0. Dean. "Emissions of Honcondensable Gases and Solid Materials from the
Power Generating Units at the Geysers Power Plant." Report 7485.16-74. Pacific Gas and Electric Company, Department
of Engineering Research. July 30, 1974. 13 pp.
-------
existing units to transfer the gases from the gas ejectors to
the cooling towers. The noncondensable gases routed from the
gas ejector are essentially "scrubbed" by cooling water in the
cooling tower. An iron catalyst added to the cooling water
promotes the oxidation of hydrogen sulfide to elemental sulfur.
The sulfur sludge is removed in settling ponds and conveyed to
a disposal site. Overall H2S abatement levels in excess of 90
percent have been reported.1
Future generating units will use an alternate control
technique. In the proposed new units, surface condensers will
be substituted for direct contact condensers: the exhaust
steam will no longer be directly contacted with cooling water.
Up to 90 percent of the H2S in the condensing steam will be
released by the off-gas ejectors. The off-gas will be conveyed
to a Stretford unit, where H2S will be oxidized to elemental
sulfur. The sulfur sludge produced by the Stretford will
probably be conveyed to a disposal site. About 10 percent of
the H2S in the condensing steam will remain in the steam
condensate. In current designs, this condensate will be added
to the circulating cooling water. The H2S in the cooling water
will be stripped at the cooling tower and emitted to the
atmosphere. The amount of H2S emitted at the cooling tower can
be reduced by treatment of the condensate from surface condensers
with H202 or Os. This treatment and the use of a Stretford
Resource Planning Associates, Inc. Western Energy
Resources and the Environment: Geothermal Energy!Prepared
for U.S. Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 79.
-178-
-------
for treatment of the ejector off-gas remove about 99 percent
of the H2S in the inlet steam stream.1'2
Other processes are being developed to remove H2S from
geothermal steam upstream of the power plant. The presence of
ammonia and carbon dioxide complicates the selection of absorp-
tion liquors for the removal of H2S. The EIC Corporation is
developing a scrubbing system using a solution of a metal salt,
such as CuSO,,, to convert the H2S to various copper sulfide
precipitates. CuSOt» is regenerated on-site by oxygen pressure
leaching. Removals in excess of 90 percent have been routinely
achieved. Full scale testing on a steam flow of about 100,000
Ib/hr is being considered.3'^ Another scrubbing process is
being developed by Republic Geothermal, Inc. and FMC Corporation.
The Republic/FMC process uses an aqueous hydrogen peroxide and
sodium hydroxide solution to oxidize the H2S to various sulfates
and elemental sulfur. Removal efficiencies of up to 96 percent
have been obtained in pilot tests.5 The Republic/FMC process is
intended mostly for control of emissions during drilling.
Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S. Environ-
mental Protection Agency, Contract No7 68-01-4100. Washington,
D.C.: U.S. Environmental Protection Agency, May 1977, p. 80.
2Ramachandran, G., et al. Economic Analyses of Geothermal
Energy Development .in California, 2 Vols.Stanford Research
Institute.Prepared for U.S. Energy Research and Development
Administration and California Energy Resources Conservation and
Development Commission. Contract No. ERDA/SAN E(04-3)-115-P.A.
108. May 1977. p. 41.
3Harvey, W. W. and F. C. Brown. "The CuSO., Process for
Removal of H2S from Geothermal Steam." Geothermal Resources
Council, Transactions. Vol. 1, May 1977, pp. 135-136.
"•Tornany, J. P. "Air Pollution Control Plans for Geothermal
Energy Plants." Geothermal Resources Council, Transactions.
Vol. 1, May 1977, pp. 295-296.
5 Ibid.
-179-
-------
As previously discussed in Section 8.5.3.1, estimates of
emissions from the development of liquid-dominated systems can
be prepared only from a detailed site-specific analysis of the
chemistry of the geothermal fluid.1
In flashed-steam systems, essentially all of the noncon-
densables present in the geothermal fluids are vented to the
atmosphere. Control techniques similar to those developed at
The Geysers should be applicable.2 If reinjection of condensed
steam and residual brine is required, the only emission sources
are off-gas ejectors unless condensed steam is used as cooling
water make-up.
In binary power plants, if the geothermal fluid is maintained
at reservoir pressure, no noncondensable gases are emitted: the
gases are maintained in solution in the brine.3 If the geo-
thermal fluid issues as a two-phase mixture, noncondensables
are separated from the liquid at the binary heat exchanger, and
subsequently released to the atmosphere.
Potential air emissions from hot rock resource developments
have not been discussed quantitatively or qualitatively.
Essentially no noncondensable gases have been detected during
initial operation of the demonstration facility at Fenton Hill,
New Mexico."
1 Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 74.
2Ibid.
Private communication with M. C. Smith, December 13, 1977.
-180-
-------
Concentrations of noncondensable gases emitted from an
uncontrolled vent at the geothermal loop experimental facility
in Nilands, California are shown in Table 8-57. Emission rates
have not been reported.
TABLE 8-57.
Species
CONCENTRATIONS OF VARIOUS CHEMICAL SPECIES
IN NONCONDENSABLE EMISSIONS FROM NILAND
TEST FACILITY
Concentration (by volume)
H2S
CO 2
H2
N2
CH,,
C2H6
1500-4900 ppm
96-98%
< 0.05 -0.34%-
0.2-0.7%
0.5-1.4%
<0.03%
Source: Phelps, P. L. and L. R. Anspaugh, eds. Imperial Valley
Environmental Project: Progress Report.UCRL-50044-76-1,
Lawrence Livermore Laboratory.Prepared for U.S. Energy
Research and Development Administration under Contract
No. W-7405-Eng-48. Livermore, CA. p. 40.
8.7.3.2 Water Effluents
The most significant water effluents discharged by a
geothermal power plant are cooling tower blowdowns and spent
geothermal brines. The ultimate disposal of these wastes is
dependent on the chemistry of the effluent, adjacent land uses,
and the geothermal plant design. Disposal may be one or a
combination of the following practices:
-181-
-------
reinjection,
discharge to surface waters, or ,
disposal to lined or unlined evaporation or
sedimentation ponds.
Reinjection is usually most desirable.1
Each 100 MWe of generating capacity at The Geysers produces
about 1100 acre-feet per year of excess steam condensate which is
withdrawn from the cooling system as blowdown.2 Cooling tower
blowdowns from flashed-steam and brine power plants have been
quantified in Section 8.7.2.4. Total quantities of blowdown
and spent brine to be disposed are summarized in Table 8-58.
The brine flows are based on the geothermal fluid requirements
defined previously in Section 8.5.2. Characteristics of these
water effluents are highly site and process specific.
Some potential exists for contamination of ground water if
the spent brine and blowdown are disposed by reinjection. How-
ever, this potential hazard can be reduced to insignificance
by proper and complete casing of the reinjection wells. Rupture
of the piping network is rare, but can be a source of contamina-
tion of surface water.
1Morrison, R. "Surface Disposal of Geothermal Brines."
Geothermal Energy Magazine 5(8): 40-42, August 1977.
2Resource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency,Contract No. 68-01-4100.
Washington, B.C.: U.S. Environmental Protection Agency, May
1977, p. 56.
-182-
-------
TABLE 8-58- WATER EFFLUENTS PRODUCED DURING POWER PRODUCTION AT A 100 MWe POWER
PLANT
Geothermal Resource - Conversion Technology
Cooling Water Slowdown
acre-feet/year
Spent Brine
acre-feet/year
1. Hot Water
a. Binary fluid cycle
b. Flashed steam cycle
3,200
3,300-3,400
51,000
42,000-43,000*
52,000d'e
2. Hot rock - binary fluid cycle
3,000
17.0008
20,000h
i
»-•
CD
u>
I
3. Dry steam - direct steam cycle
1,100
Assumes use of surface heat exchangers.
Assumes use of surface or direct contact heat exchangers.
CAssumes no legal restriction requiring reinjection and that condensate is not required to dilute
residual brine.
Excess steam condensate is classed as spent brine.
Assumes legal restriction requiring complete reinjection of extracted fluids.
Assumes cooling requirement based on hot water conversion technologies.
Assumes that cooling water blowdown can be used as make-up water for hot rock development.
Assumes that cooling water blowdown cannot be used as make-up.
-------
Additional, unquantified water effluents are associated
with the operation of hydrogen sulfide removal equipment. The
quantities of these wastewaters are certainly less than quanti-
ties of spent brine. However, some of these wastes may be highly
toxic. Disposal will typically require evaporation or sedimenta-
tion ponds or reinjection.
8.7.3.3 Solid Wastes
Solid wastes generated during power production include
sludges from hydrogen sulfide removal and solids from scale
removal. These solid wastes have not been described quantita-
tively or qualitatively.
8.7.3.4 Noise Pollution
Noise during power production is chiefly associated with
the operation of gas ejectors, cooling towers, and turbine-
generators. Typical noise levels for these operations as
observed at The Geysers are summarized below:1'2'3
lResource Planning Associates, Inc. Western Energy Resources
and the Environment: Geothermal Energy. Prepared for U.S.
Environmental Protection Agency, Contract No. 68-01-4100.
Washington, D.C.: U.S. Environmental Protection Agency, May
1977, p. 65.
2Ecoview Environmental Consultants. Draft Environmental
Impact Report for Geothermal Development of Union Oil Company's
Leaseholds on the Upper Part of the Squaw Creek Drainage at
The Geysers, .Sonoma County. California"Napa, California, 1974.
3Reed, M. J. and G. E. Campbell. "Environmetal Impact of
Development in The Geysers Geothermal Field, U.S.A." Proceedings
Second United Nations Symposium on the Development and Use of
Geothermal Resources.San Francisco, CA, May 20-29,1975.
Washington, D.C.:U.S. Government Printing Office, 1976,
pp. 1399-1410.
-184-
-------
Noise Source Duration Noise Level Distance
Jet gas ejector Continuous 5-10 feet
Unattenuated 117 dBA
With acoustical insulation 84 dBA
Cooling tower Continuous 80-90 dBA 5-10 feet
Turbine-generators building Continuous 70 dBA Outside
8.7.3.5 Occupational Health and Safety
Safety hazards associated with the operation and maintenance
of a geothermal- power plant have not been extensively studied to
date. These hazards are similar to those at fossil-fuel plants.
Health hazards are chiefly associated with worker exposure to
toxic gases, as described in Section 8.5.3.5.
8.7.3.6 Odor
Odors at geothermal developments are chiefly associated
with the presence of ammonia and hydrogen sulfide, as described
in Section 8.5.3.6. These gases can be emitted in malodorous
concentrations via the noncondensable gas vent and the cooling
towers.
The inputs and outputs associated with geothermal power
plants are summarized in Table 8-59.
8.7.4 Direct Thermal and Other Uses of Geothermal Energy
On a worldwide basis, non-electrical applications of geo-
thermal energy represent an average energy consumption of
-185-
-------
TABLE 8-59.
SUMMARY OF INPUTS AND OUTPUTS OF A GEOTHERMAL POWER PLANT
PRODUCING 100
Hot water/
binary fluid
Input Requirements
Manpower
• construction 257 Ban-years
• operating 28 Ben
Materials
• steel In piping network 2200 tona
EconoBlcs
• capital coata* $66.4 Billion
• power generation coata 3.1c/kwhc
Water
• total Bake-up 13,000 acre ft/yr'
Land 31 acrea
1 Ancillary energy None
00 Air eBlaalona
1 • carbon dioxide Unknown
• hydrogen sulflde
• Methane
• hydrogen
• aBBonla
• arsenic
• boron
• Bercury
Water effluents
• blowdown 3,000 acre ft/yr
• spent brine 51,000 acre ft/yr
Solid waatea Not quantified
Noise pollution <90 dB(A)
Occupational health Hot quantified
and aafety
Odora NH,
II, S
Hot water/ Hot rock/
ateaa flashing binary fluid
260 Ban-years . 230 Ban-years
28 Ben 26 Ben
2400 tona 360 tona
$131.4 Billion $40.9 Billion
4.7c/kwhc 1.6c/kwhc
13.000 acre ft/yr* 13,000 acre ft/yr*
37 acrea 15 acres
None None
Unknown Unknown
3.000 acre ft/yr 3.000 acre ft/yr
52,000 acre ft/yr 20.000 acre ft/yr
Not quantified Not quantified
<90 dB(A) <90 dB(A)
Not quantified Not quantified
Nil] Unknown
H2S
Dry ateaa/
direct uae
170 Ban-years
8 Ben
40 tona
2.0c/kwhd
Hon.
4 acrea
Nona
5500 Ib/hr
380 Ib/hr
330 Ib/hr
80 Ib/hr
330 Ib/hr
0.01 Ib/d
21 Ib/d
0.0006 Ib/d
1.100 acre ft/yr
—
Not quantified
<90 dB(A)
Not quantified
NH,
H2S
Based on ISO'C resource.
Including capital charges.
C1976 dollars.
1977 dollars.
eCoBplete relnjectlnn of geothernal fluids.
-------
about 6000 MW^.l While non-electrical applications worldwide
are the largest users of geothermal energy, non-electrical uses
in the United States are still relatively undeveloped. In 1975,
less than five percent of the heat extracted from geothermal
resources in the United States was used in direct thermal
applications.2 The U.S. Department of Energy anticipates that
by 1985 direct thermal uses will represent one-fourth to one-
third of the total usage of geothermal energy in the U.S.3
Some of the anticipated direct thermal uses of geothermal
energy are shown in Figure 8-12. Direct thermal applications
can utilize the heat of low-to-medium temperature geothermal
resource more efficiently than electric power generation. Since
geothermal resources of low-to-medium temperature are larger
than those of high temperature, non-electrical applications
also have the largest potential resource base.1*
toward, J. H. "Principal Conclusions of the Committee on
the Challenges of Modern Society Non-Electrical Applications
Project." Proceedings Second United Nations Symposium on the
Development and Use of Geothermal Resources.San Francisco, CA,
May 20-29, 1975.Washington, D.C.:U.S. Government Printing
Office, 1976, pp. 2127-2139.
zlbid.
3U.S. Energy Research and Development Administration.
Program Approval Document, Geothermal Energy Development, Fiscal
Year 1977. January 17, 1977.p. 3.
^Reistad, G. M. "Potential for Nonelectrical Applications
of Geothermal Energy and Their Place in the National Economy."
Proceedings Second United Nations Symposium^on the Development
and Use of Geothermal Resources.San Francisco, CA, May 20-29,
1975.Washington, D.C.:U.S. Government Printing Office, 1976,
?p. 2155-2164.
-187-
-------
41
g
I
a
m
•c
200.
190
180.
170-
160
150.
140-
130-
120-
110-
100.
90-
80-
70-
60'
50-
40-
30-
20-
Evaporation of high cone, solutions.
Refrigeration by ammonia absorption.
Digestion in paper pulp, Kraft.
Heavy water via hydrogen sulfide process.
Drying of diatooaceous earth.
Drying of fish neal.
Drying of timber.
Alumina via Bayers process.
Temp, range of
- conventional
power production
Drying farm products at high rates.
Canning of food.
Evaporation in sugar refining.
Extraction of salts by evaporation and crystalization.
Fresh water by distillation.
Most multiple effect evaporations, concentration of saline solutions.
Refrigeration by medium temperatures.
Drying and curing of light aggregate cement slabs.
Drying of organic materials, seaweeds* grass, vegetables, etc.
Hashing and drying of wool.
Drying of stock fish.
Intensive de-icing operations.
Space heating.
Greenhouse space heating.
Refrigeration by low temperature-
Animal husbandry.
Greenhouses by combined space and hotbed heating.
Mushroom growing.
Balneological baths.
Soil warming.
Swimming pools, biodegradation, fermentations.
Warm water for year around mining in cold climates.
Hatching of fish. Fish farming
De-icing.
Figure 8-12. Recommended Temperature of Geothennal Fluids
for Various Direct Thermal and Other
Non-Electrical Applications.
Source: Lindal, B. "Industrial and Other Applications of Geo-
thermal Energy." Geothennal Energy. H. C. H. Armstead,
(ed.). Paris: UNESCO, LC No. 72-07138, pp. 135-148.
-188-
-------
Geothermal energy can be utilized in certain "multipurpose"
developments. As one example, at the Raft River Geothermal
Project in Idaho, a 3008F resource is being developed to furnish
electricity, industrial process heat, and district heating.1
Such multipurpose developments are mostly confined to geothermal
resources containing few dissolved solids.
The following sections provide a brief overview of direct
thermal and other non-electrical applications of geothermal
energy. A discussion of residential and commercial applications,
agricultural applications and related topics, and industrial
applications follows. Since non-electrical uses of geothermal
energy are diverse, no input/output data for non-electrical
applications are provided. Such data are largely unavailable.
Some economic data are presented in the final section.
The following discussion draws heavily from a paper by
J. H. Howard.2
8.7.4.1 Residential and Commercial Applications
In 1975, the world-wide use of geothermal energy for
commercial and residential applications represented an average
energy consumption of about 400 MWt. Uses in these applications
are chiefly space and district heating and cooling.3
1Idaho National Engineering Laboratory. Idaho Geothermal
Development Projects, Report for the Year Ending February 1976".
U.S. Energy Research and Development Administration,1976.
2Howard, J. H. "Principal Conclusions of the Committee on
the Challenges of Modern Society Non-Electrical Applications
Project." Proceedings Second United Nations Symposium on the
Development and Use of Geothermal Resources.San Francisco, CA,
May 20-29, 1975.Washington, D.C.:U.S. Government Printing
Office. 1976. pp. 2127-2139.
312>id.
-189-
-------
In the United States, geothermal waters have been used to
heat homes and buildings in Boise, Idaho and Klamath Falls,
Oregon. Other countries with large space and district heating
applications are Iceland, Hungary, the Soviet Union, France,
New Zealand, and Japan. The largest application is found in
Reykjavik, Iceland, where the average energy consumption was
about 170 MWt in 1975.'
Hot-water and forced-air residential heating systems are
easily adapted for the use of geothermal energy. If scaling
and corrosion are minimal, the geothermal fluid can be used
directly in existing hot-water equipment. In forced-air
systems, the temperature of the hot air leaving the heater is
usually around 55 to 60°C. Geothermal fluids with- temperatures
around 70 to 80°C or greater are sufficient for this application.
The furnace and fan of the present forced air systems are
replaced by a surface heat exchanger and a somewhat larger fan.2
The Rotarua International Hotel in New Zealand features a
geothermal heating and cooling system consisting of a lithium
bromide absorption unit designed for climate temperatures from
-4°C to +30°C.3 Geothermal heating and cooling systems using
ammonia absorption are also feasible.1*
toward, J. H. "Principal Conclusions of the Committee on
the Challenges of Modern Society Non-Electrical Applications
Project." Proceedings Second United Nations Symposium on the
Development and Use of Geothermal Resources.San Francisco, CA,
May 20-29, 1975.Washington, D.C.:U.S. Government Printing
Office, 1976, pp. 2127-2139.
2Ibid..
3Ibid.
^Taylor, R. J., W. J. Toth, and D. W. Stowe. "Ammonia
Absorption Geothermal District Heating and Air-Conditioning
System." QM-77-018, Applied Physics Laboratory, John Hopkins
University. March 1, 1977.
-190-
-------
8.7.4.2 Agricultural Applications
In 1975, the average worldwide usage of geothermal energy
in agricultural applications amounted to about 5500 MWt, or over
90 percent of total usage of geothermal energy in non-electrical
applications. Two uses have been identified: heating (in
greenhouses, animal husbandry, and aquaculture), and irrigation.
These applications are discussed briefly below.l
The largest agricultural application of geothermal waters
is in greenhouses for both heating and irrigation. Over 90
percent of the geothermal energy used in agricultural applica-
tions is associated with large acreages of greenhouses in the
Soviet Union. This application is more common in areas where
the growing season is short. Most geothermally heated green-
houses use geothermal waters directly on the soil alone or
mixed with cool potable or irrigation waters.2'3
Advantages of using geothermal waters in greenhouses
include increased crop yields, year-round crop cultivation, and
control of predators, pests, and frosts.1* In the United States,
toward, J. H. "Principal Conclusions of the Committee on
the Challenges of Modern Society Non-Electrical Applications
Project." Proceedings Second United Nations Symposium on the
Development and Use of Geothermal Resources"!San Francisco, CA,
May 20-29, 1975.Washington, D.C.:U.S. Government Printing
Office, 1976, pp. 2127-2139.
2ibid.
3Howard, J. H., ed. Present Status and Future Prospects
for Nonelectrical Uses of Geothermal Energy.UCRL-51926.
Lawrence Livermore Laboratory.LivermoreT CA: University of
California, October 3, 1975.
'*Cheremisinoff, P. N. and A. C. Morresi. Geothermal Energy
Technology Assessment. Westport, Conn.: Technomic Publishing
Company, 1976, p. 107.
-191-
-------
soil warming in field experiments near Corvallis, Oregon increased
the yield of corn silage by 45 percent, tomatoes by 50 percent,
soybean silage by 66 percent, and beans by 39 percent. Relatively
pure geothermal waters are required if the waters are directly
applied to the soil. More saline waters would require the
transfer of heat via surface heat exchangers.1
Relatively pure geothermal waters may be directly applied
to lands for irrigation of crops. This is especially attractive
in arid areas.*
In animal husbandry, geothermal waters are used not only
for space heating, but also for the cleaning, sanitizing, and
drying of animal shelters and wastes. Poultry, swine, and
cattle respond to optimum thermal environments with increased
production, growth rate, and feeding efficiency.3'"*
Aquaculture is "the practice of cultivating aquatic
species under controlled environmental conditions in order to
establish and maintain optimal environmental conditions year-
round for increased rate of growth and feed efficiency."5
Geothermal waters can supply the heat required to maintain optimum
temperatures.
toward, J. H., ed. Present Status and Future Prospects for
Nonelectrical Uses of Geothermal Energy"! UCRL-51926. Lawrence
Livermore Laboratory.Livermore, CA: University of California,
October 3, 1975, pp. 62-64.
2iMd., pp. 108-109.
3ibid., p. 64.
"*Yarosh, M. M. , et ail. Agricultural and Aquacultural Uses
of Waste Heat. Report Number ORNL-4797.Oak Ridge National
Laboratory, 1972.
bHoward, J. H., ed., op.cit., pp. 62-64.
-192-
-------
8.7.4.3 Industrial Applications
Present industrial applications of geothermal energy have
been summarized by Howard1 and are shown in Table 8-60. The
average energy consumption of these applications represents a
total utilization of 150-200 MWt of geothermal energy.
Geothermal fluids can supply industry with direct heat,
process steam, and raw materials. Applications using the
geothermal resource as a source of heat or steam include:
process heating, evaporation, drying, distillation, refrigeration
by absorption machines, sterilization, washing, and de-icing
(as in mining operations). Raw materials contained in geothermal
waters include salts and other valuable chemicals.2 Methods
for the extraction of potassium, lithium, and calcium are
available. The Italians formerly extracted large quantities
of boric acid, ammonium bicarbonate, ammonium sulfate, and
sulfur from the steam jets at Larderello. Processes are being
developed in the Soviet Union for the extraction of alkali and
alkali-earth metals, and trace elements.3 In particular, the
geopressured region of the Gulf Coast contains significant quan-
tities of methane. In some instances, geopressured resources
may be important simply for the recovery of methane.
toward, J. H. "Principal Conclusions of the Committee on
the Challenges of Modern Society Non-Electrical Applications
Project." Proceedings Second United Nations Symposium on the
Development and Use of Geothermal Resource's"! San Francisco, CA,
May 20-29, 1975.Washington, D.C.:U.S. Government Printing
Office, 1976, pp. 2127-2139.
2Howard, J. H., ed. Present Status and Future Prospects
for Nonelectrical Uses of Geothermal Energy.UCRL-51926.
Lawrence Livermore Laboratory.LivermoreT CA: University of
California, October 3, 1975.
3Stevovich, V. A. Geothermal Energy. Contract No. MDA-903-
76C-0099. Defense Advanced Research Projects Agency. Washington,
D.C.: November 1975, pp. 196-203.
-193-
-------
TABLE 8-60.
PRESENT INDUSTRIAL APPLICATIONS
OF GEOTHERMAL ENERGY
Application Couatry
Hood aad pa
laduetry
par
Deecrtpcloa of
«ppllcat1aa
staaa. flow tate,
or' Water no* tat*
fowr to
Meaavatta Coaaaata
Palp aod paper
Proceeelat aad • oaall
eamoK of electrical
paMr feaeracloa.
Kraft i
-400.000 tta/kr of
100
123
Veaaar factory
TlBkar erylaf
tiaaklae end drytai
of vood
Mlalai
DtatoaacaoM Earth
Plaae
Staaa drylae
Icalaad
Op to JO toae/kr -35
of itaaai at
1«3*C/10 atf. Total
40 to JO teaa/kr
aeeardlaf to the
«ia»pa. Uollkora
no*—iia.t
Ccal/kr.
Utilised— ».J
Ccal/kr.
Salt pla«t
Salt plaat
Sulfur alalat
Calctua chlotldo
tone actd
Forte aeU,
kiearbonat<
mlfata. oalfar
Dry le«
Phlllppt
Caafoetlaaair
loduotxt
Crala
Iravlat aM
dUt lilac loo
Stock flak
Oalted Statea
Italy
Oaltad SeatM
Fhlllpplaao
IcoUad
of aalt froa
oaa votor.
Prodoctlaa of aalt froa
ooa vatar
Sdfmr nttactlaa fraa
tka H««I lao«ia«
froa • valcaao
•acovory of aotaaala*
eUorlda frea tka
nathomal orla*
-130
aaltVr
Oacortala kat laall
dollmrad to atlla by
•0,000 Ib/kr of MO
pale atoaa ani •
U.OOO Ib/hr of 100
polf ataaa Mhlck ara
obtdMd by flaaklat
«ot atoaB at tka vallbor
to ••tall* H»aa.
•o aatalla (l«aa.
•o datalta furalabad,
Upertod to occur
la other placaa.
Drodsia* la tba laka to
doaa oaly la tka
tmmti Hhlla tka
plaat ram* thrwskaat
tka yaar. HM roportad
XI. 5 Ccal/hr appaara
to bo kick or aaavaaa
aaparaaatad ataam at
10 ata.
•o loaaar la opancloa
Saa natar krouabt 1 to
to plaat. Ihraa aradaa
of aalt prodnead.
Uaaopklatieatad
oparatloa that kaa
kacoaa unaconoalc.
-13 to If
Prodactloa of dry lea
fnai COi U tko Saltoa
haati rotary Ula
ko loaaar la oparatloa.
Largo prodactlaa
kafora 1H«.
Bally rtca aroeaaaiac
capacity 110 kj.
Dacortala bat aaall
<2.3
Flak drytaf la akalf
dryara.
Curiac of llakt
Uaahlat aa4 diylM of
Icalaad
Drylaf
for
-W 1/aoc at 100-C
rradactloa of MOO
taaa of dry taaiiaad
par yaar. lack toa
rooalm $1.40 nortk
of oaorty par toa of
aaavMd If tka oaargy
coata S0.4S par Ccal.
-J to *
Faw dataila |i*aa. uaoa
N*C vatar. apriot tourc*.
Falay drytac tlaa cut to
10 a*aata* froa 4-«
hra. Modal unoar taat.
•o dataila |l«a. Ono
nail uaod.
OMa cxcaaa xacor froa
cnawrelal kaatla« «yac»a
la loykj.vtk durlat suaMr
la local itock tUh pro-
caaalag caatar.
BO aatalla (l«aa.
•o datall* (!««•
laportod to occur in
too or aoro cowncrlaa.
Doaerlptloa of propoaad
•yataa (l«aa, oaly
Mord-of-«ouck Indlca-
cloa that lyatoa 1«
praaaatly In oparaclon.
*nta "aaaaclatad powar la aaaavacta" oacry I* aa •attaato of tka rata at uhlek aaaray ia auppllod to aad avallakla Co bo utilised by the proee*«.
umiall* not the eaerfy flov rate froa the well.
Curreat atarua of appltcatloa la uakaowi.
Source: Io«rd J. •. -Principal Caaelualoaa of tka Coaalttoa oa tka Chelleaaee of Hadara Society «oa-tleetrlcal Appllcacloae Project."
Ptocoedlaaa Secoad Ualtad »atieaa S?a»
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8.7.4.4 Economics
D. F. Towse1 has estimated the costs of various non-electrical
utilizations of geothermal energy. These preliminary costs
estimates are presented as Table 8-61. The costs are based
largely on experience for Klamath Falls, Oregon,2 Iceland,3
and the Imperial Valley of California," and a feasibility study
of the Gulf Coast.5
toward, J. H., ed. Present Status and Future Prospects
for Nonelectrical Uses of Geothermal Energy.UCRL-51926.
Lawrence Livermore Laboratory.Livermore, CA: University of
California, October 3, 1975, pp. 80-86.
2Culver, G., J. W. Lund, and L. Svanevik. Klamath Falls
Hot Water Well Study. UCRL-13614. Lawrence Livermore Laboratory,
1974.
3Zoega, J. "The Reykjavik Municipal Heating System."
Proceedings International Conference on Geothermal Energy for
Industrial, Agricultural, and Commercial-Residential UsesT
Klamath Falls, Oregon:Oregon Institute of Technology, 1974.
"*U.S. Department of the Interior, Bureau of Reclamation.
Geothermal Resource Investigations. East Mesa Test Site, Imperial
Valley. "CXStatus Report, November 1974.
5DES Engineers, Inc. Geothermal Resource Utilization -
Paper and Cane Sugar Industries.UCRL-13633.Lawrence Livermore
Laboratory,1975.
-195-
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TABLE 8-61. ESTIMATED COSTS OF NON-ELECTRICAL UTILIZATIONS OF GEOTHERMAL ENERGY
J
>
\
*
1
!
§
s
1
Example
number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
NOTES
Not to
rather
Source:
Meat
utilization* Type of Number of
(106 Btu/hr.) example users
2,500,000 Pulp & Paper Mill
419,000 Industrial freezing
200,000 Industrial refrigeration
84,100 Food processing
84,100 Commercial bldgs-heat
55,100 Industrial drying
55,100 Commercial bldgs.
(heat 6 cool)
25,000 College
25,000 (4 Hospitals)
25,000 (10 Commercial Buildings)
25,000 (100 Single-family
residences)
2,453 Commercial-heating
2,453 Single-family residences
175 Single-family residences
(1) 13,000' deep 250°F U.S. Gulf Coast
(2) 8,500' deep 180°F U.S. Gulf Coast
(3) 6,000' deep 225°F Imperial Valley
be confused with capacity of the system
than potential for provldl-t; heat.
Howard, J. H. . ed. Present Status
of Geothermal Energy. UCRL-51926.
1
1
1
1
10
1
10
1
4
10
100
1
10
1
to produce
106 Btu/hr
per user
2,500,000
419,000
200,000
84,100
8,410
55,100
5,510
25,000
6,250
2,500
250
2,453
245
175
(4) 6,000
(5) targe
(6) Small
heat energy
Capital costs ($)
Wells Distribution
15,700,000 0
2,720,000 0
870,000 0
470,000 0
470,000 25,000
470,000 0
470,000 25,000
40,000 0
40,000 10,000
40,000 25,000
40,000 250,000
7,000 0
7,000 25,000
7,000 0
1 deep 225°F Imperial Valley
System, Klamath Falls, Oregon
System, Klamath Falls, Oregon
Annual geo-
thermal fuel
costs per user
2,905,000
496,096
154,000
85,362
8,965
85,349
8,970
16,925
4,538
2,000
476
912
549
912
- -190°F
- -190°F
Costs per
106 Btu
used ($)
1.162
1.184
0.770
1.015
1.066
1.549
1.628
0.667
0.726
0.800
1.906
0.372
2.242
5.217
Notejs
(1)
(1)
(2)
(3)
(3)
(A)
(4)
(5)
(5)
(5)
(6)
(6)
(6-)
; i.e., this expresses heat actually used,
and Future Prospects for Nonelectrical Uses
Lawrence
Livermore
Laboratory. Livermore,
CA.: University of California, October 3, 1975, p. 82.
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