EPA
Interagency Geothermal
Coordinating Council
Environmental Controls Panel
United States
Environmental Protection
Agency
Energy Processes
Division
April 1980
Research and Development
Status of Environmental
Controls for Geothermal
Energy Development
DRAFT REPORT
Interagency
Energy/Environment
R&D Program
Report
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STATUS OF ENVIRONMENTAL CONTROLS
FOR
GEOTHERMAL ENERGY DEVELOPMENT
Presented to the
Interagency Geothennal Coordinating Council
by the
Environmental Controls Panel
David R. Berg, Chairman
Clifton McFarland, Vice-Chairman
April 1980
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ABSTRACT
This report presents the initial findings and recommendations of
the Environmental Controls Panel to the Interagency Geothermal
Coordinating Council (IGCC). The Panel has been charged to assess
the adequacy of existing environmental controls for geothermal energy
systems, to review ongoing programs to develop environmental con-
trols, and to identify controls-related research areas where redirec-
tion of federal efforts are appropriate to assure the availability of
controls on a timely basis. In its deliberations, the Panel placed
greatest emphasis on the use of geothermal resources for electricity
generation, the application of geothermal energy receiving greatest
attention today. The Panel discussed major known environmental con-
cerns and their potential impact on the commercialization of geo-
thermal resources, control options, regulatory considerations, and
ongoing and planned research programs.
The environmental concerns reviewed in this report include: air
emissions, liquid discharges, solid wastes, noise, subsidence, seis-
micity, and hydrological alterations. For each of these concerns a
brief description of the concern, associated legislation and regula-
tions, control approaches, federal funding trend, and the Panel's
recommendations and priorities are presented. In short, the Panel
recommends that controls-related research efforts be rebalanced and
enhanced, with the greatest emphasis placed on controls for hydrogen
sulfide (H2S) and non-H2S gaseous emissions, injection monitoring
methods, systems to treat and use nongeothermal waters for environ-
mental control purposes, solid waste characterization and management
methods evaluation, and subsidence controls.
111
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ACKNOWLEDGMENTS
The Panel would like to thank The MITRE Corporation and Engi-
neering and Economics Research, Incorporated, for their assistance in
producing this report. The Panel would also like to recognize its
members who contributed time and efforts toward the success of this
report. Without the contributions of this group of knowledgeable
individuals this report would not have been possible. The Panel
members include:
David Berg, Chairman (EPA)
Clifton McFarland, Vice-Chairman (DOE)
Robert Hartley (EPA)
Gerald Katz (DOE)
Sie Ling Chiang (USGS)
Karl Duscher (BLM)
William Spalding (USFWS)
David Allen (DOE)
Tom Ladd (DOD)
Douglas Boehm (DOE)
Ron Loose (DOE)
Robert Oliver (DOE)
William Rice (DOE)
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TABLE OF CONTENTS
Page
LIST OF ILLUSTRATIONS vi
LIST OF TABLES vi
EXECUTIVE SUMMARY vii
1.0 INTRODUCTION 1
1.1 Environmental Controls Panel 1
1.2 Environmental Concerns 3
1.3 Federal Environmental Controls Budget 3
2.0 ENVIRONMENTAL CONCERNS, ASSOCIATED LEGISLATION H
AND REGULATIONS, AND CONTROL OPTIONS
2.1 Air Emissions 13
2.2 Liquid Discharges 20
2.3 Solid Wastes 24
2.4 Noise 27
2.5 Subsidence 29
2.6 Seismicity 32
2.7 Hydrological Alterations 35
3.0 RECOMMENDATIONS OF THE ENVIRONMENTAL CONTROLS PANEL 39
3.1 Priorities for Research in Environmental Controls 39
3.2 Other Recommendations 44
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LIST OF ILLUSTRATIONS
Page
Figure Number
1-1
1-2
1-3
Federal Geothermal Environmental
Research Program - Budget Summary
Federal Geothermal Environmental
Research Program - Controls-Related
Budget
Federal Geothermal Environmental
Research Program - Controls-Related
Budget by Concern
LIST OF TABLES
Page
Table Number
1-1
l-II
l-III
3-1
3-11
Federal Geothermal Environmental
Research Program - Budget Summary by
Agency
Federal Geothermal Environmental
Research Program - Controls-Related
Budget by Agency
Federal Geothermal Environmental
Research Program - Controls-Related
Budget by Concern
Control-Related Research Areas by
Geothermal Environmental Concern
Priorities for Environmental Controls
Research
42
vi
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EXECUTIVE SUMMARY
The Environmental Controls Panel of the Interagency Geotheraal
Coordinating Council has investigated the availability of existing
environmental controls for geothennal energy systems. The Panel
assessed the adequacy of federal research in light of current
knowledge about the major environmental concerns that may interfere
with the commercialization of geothermal energy resources. The Panel
examined seven categories of environmental concerns: air emissions,
liquid discharges, solid wastes, noise, subsidence, seisraicity, and
hydrological alterations.
The potential impact in each environmental category on geo-
thermal energy commercialization, the availability of controls ,'
regulatory considerations, and the extent and adequacy of ongoing
research were considered. Finally, the Panel grouped in priority
order the research areas and recommended steps to modify federal
research efforts to assure the availability of controls on a timely
basis.
The Panel concludes that the environmental problems associated
with geothermal energy development may pose obstacles to the
commercialization of geothermal resources. The concern over the en-
vironmental impact of geothermal development has already delayed or
suspended activity at some sites (particularly in The Geysers area of
Northern California). While air emissions, particularly hydrogen
sulfide, have posed the greatest environmental concern to date, the
uniqueness of each geotherraal resource, the rapid pace of exploration
for resources, and the complexity of geothermal fluids and discharges
assure that other environmental issues will present difficulties for
full use of potential geothermal energy resources in the United
States.
The next several years could be critical to geotherraal develop-
ment, because the geothermal industry is in a dynamic state and com-
mercial activity is just beginning at several resource sites. In
addition, many environmental regulations are not yet crystallized and
adequate environmental controls are not fully available. The Panel
found that the interests of all parties can best be served if
opportunities for industry-government cooperation are pursued.
Several specific research areas are identified where additional
federal resources are recommended. Federal resources could be
combined with those of industry to develop and demonstrate needed
environmental controls in a cost-effective and timely manner.
vii
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The paragraphs below summarize the Panel's assessment of the
current situation in each of the seven environmental areas. Fol-
lowing are brief discussions of federal funding trends and the Pan-
el's recommendations for the federal environmental controls program.
AIR EMISSIONS
Because of their prevalence and offensive odor, hydrogen sul-
fide (H£S) emissions are of major environmental concern in geo-
thermal development. Emissions occur during well drilling, venting
and cleanout, power plant operation and steam stacking (the release
of steam at vapor-dominated geothermal resources during turbine
shutdown). A few states (e.g., California, New Mexico, and Hawaii)
have established ambient H2S standards, although the federal govern-
ment has not done so. The state standards that currently exist
are based upon odor, but are not uniform,
The Environmental Protection Agency (EPA), under authority of
the Clean Air Act, may establish New Source Performance Standards
(NSPS) for geothermal H2S or other air emissions and may require
the application of best available control technology (BACT). BACT
is determined on a case-by-case basis under existing regulations
for prevention of significant deterioration (PSD) of air quality
under certain conditions.
Sources emitting more than 250 tons per year of f^S are subject
to EPA's PSD regulations. EPA has no current plans to promulgate
national ambient air quality standards for H2S or to designate it a
hazardous pollutant under Section 112 of the Clean Air Act. Inas-
much as H2S is a precursor to atmospheric S02, sources may be
controlled under state implementation plans.
In response to a recent court decision, however, EPA has pro-
posed comprehensive amendments to the PSD regulations (see 44FR
51924, September 5, 1979). Among them is a provision that would in
effect exempt from the BACT requirement, as well as other PSD re-
quirements, any source that would emit only noncriteria pollutants
in major amounts (44FR 51953-54 § 52.21(1) (8)). A geothermal
power plant would emit only H2S, a noncriteria pollutant, in
major amounts, if current indications hold true. Whether EPA will
make this provision final is as yet uncertain.
Insufficient data have been released to establish the environ-
mental significance of other air emissions from geothermal energy
systems. Industry sources and government researchers have, however,
indicated their concern that controls may eventually be required for
some or all of the following emissions: carbon monoxide, ammonia,
hydrocarbons, mercury, boron, and radon.
viii
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Hydrogen sulfide control technologies have been demonstrated
for geothermal operations only at the Geyers power generation site.
Existing control systems, utilized downstream of the turbine, are
the Iron Catalyst System (and its variants) and the Stretford pro-
cess; neither has been as effective as anticipated. The upstream
EIC Copper Sulfate Catalyst Process (recently demonstrated at one-
tenth scale) has advantages over existing systems in that it may
control steam stacking of I^S emissions and may also control emis-
sions of ammonia and boron. The system appears to be effective and
cost-competitive. If commercial operation meets expectations, the
EIC process may provide an acceptable control technology solution
to the H2S emission problem.
In spite of optimism regarding the EIC process, long-term
reliability, economic commercial operation, and high efficiency of
hydrogen sulfide abatement systems have not yet been assured for
any control technology. Research, development and demonstration of
new and improved technologies by both government and industry should
continue at a substantial level until a solution is conclusively
demonstrated.
LIQUID DISCHARGES
The main source of waste water from geothermal operations at
liquid-dominated fields will be the geothermal fluid itself, princi-
pally spent brine with much lesser amounts of condensate/cooling
water. Environmental problems associated with water discharges in-
clude possible contamination by dissolved metals and other sub-
stances, of surface or ground waters that might be used for drinking
(by people and/or animals) or other purposes. In most cases, the
waste water will likely be reinjected to the subsurface. Injection
not only is a disposal method, but may help to control subsidence
and to slow resource depletion. Under certain conditions, however,
injection may induce seismicity. In some cases surface discharge
of the waste water may be allowable and more desirable, particularly
where the waste water is of relatively high quality and/or water is
in short supply.
Surface water discharges will be controlled mainly by National
Pollution Discharge Elimination System (NPDES) permits under the
Federal Water Pollution Control Act. Permit conditions will be
based upon Effluent Guidelines (yet to be developed for geothermal),
or upon receiving Water Quality Standards, if the technology-based
guidelines are not sufficient to protect the receiving water.
Subsurface injection will be regulated by state-issued injec-
tion permits under authority delegated by EPA via the Federal Safe
IX
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Drinking Water Act. The State Underground Injection Control Program
regulations are now in the proposal stage. The requirements are
likely to be similar to those already in effect in many states,
requiring prior geologic and hydrologic studies, specific well
construction procedures, and subsequent ground water monitoring.
Injection regulations ordinarily require confinement rather than
treatment.
Waste treatment technologies for surface disposal applicable to
geothermal waste waters are likely to be adapted from other indus-
tries. The only affordable treatment for pollution control is
likely to be settling, filtration, and limited chemical precipita-
tion. More elaborate treatment may be applied to obtain a saleable
product or to provide fresh water where such is at a premium.
Simple conventional treatment, including chemical additives,
can be applied to spent brine prior to injection to reduce the
possiblity of scaling and plugging in the injection system and the
receiving formation. Long-term injection of geothermal spent fluids
at very high flow rates poses many uncertainties that should be
investigated. Injection well construction integrity procedures are
probably adequate. However, system and formation compatibility
must be assured, and monitoring methodologies must be developed, to
assure that injected materials do not leave their zone of confine-
ment to pollute other aquifers.
SOLID WASTES
Solid wastes from geothermal operations have taken on increased
importance because of their largely unknown character and the possi-
bility that they may be classified as hazardous wastes according to
criteria in regulations proposed under the Resource Conservation
and Recovery Act. Principal sources of solid wastes from geothermal
energy including drilling muds, waste water treament, and sludges
from air emission treatment.
Geothermal solid wastes (air and water treatment residuals and
drilling wastes) perhaps may be temporarily exempted from the hazard-
ous waste regulations due to amendment of RCRA. If found to be non-
hazardous, they will be regulated under Subtitle D of the Act (as
implemented by the individual states) which addresses nonhazardous
wastes.
Waste management technologies, such as secured landfilling, al-
ready required by some states, may be available for geothermal solid
waste disposal, although evaluations of these practices must be
undertaken. The principal needs to-be addressed are: 1) character-
izing the wastes, and 2) assessing waste management techniques. An
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additional developmental tasks is finding sites within a reasonable
distance from the geothermal operation. The costs of disposal are
likely to be high, although the recovery of minerals (e.g., silver
and lithium) in commercial quantities may in part offset these costs.
If the geothermal wastes are classified as hazardous under the
Resource Conservation and Recovery Act, disposal management costs in
some cases may be restrictive.
NOISE
Noise from geothermal operations may be excessive, particularly
from well drilling and steam venting. Other noise sources include
well cleanout and flow testing and generating unit operations.
Noise emissions will generally be regulated at the state and local
level. Occupational Safety and Health Act (OSHA) regulations may
require ear protection for workers at geothermal operations. The
Federal Noise Control Act does not specifically control geotherraal
sources but does foster control of noise from federal facilities.
The United States Geological Survey (USGS) limits noise from geo-
thermal operations on leased federal land.
Controls (shields and mufflers) are considered available at
reasonable cost for meeting standards that may be applied. Fed-
erally funded research and development in geothermal noise control
technology development does not appear warranted.
SUBSIDENCE
Subsidence may occur following the removal of large amounts of
fluid from geothermal reservoirs. Subsidence may be limited by in-
jection of the geothermal fluid or other available waters. Alterna-
tively, production can be terminated or reduced if unacceptable
levels of subsidence are detected or predicated.
Federal lessees are required to survey the land surface prior
to production and to monitor the land during protection. If subsi-
dence is determined to present a significant hazard to operations or
adjoining land uses, the USGS may require injection or other reme-
dial action. Some state and local governments may also require in-
jection if subsidence is of concern.
Research has been initiated to develop the capability to predict
induced subsidence, so that remedial actions may be taken before sub-
sidence occurs at the surface. This effort should continue at its
present level.
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SEISMICITY
Studies have shown that high pressure injection of large vol-
umes of geothermal fluid can increase the frequency of microseismic
events. It is not known, however, at what pressures and volumes the
frequency of events will increase or whether a major earthquake can
result from the lubrication of a fault. If care is taken in site
selection and monitoring is performed during operations, the impacts
of induced seismicity can be minimized.
Public agencies may initiate the installation of seismic net-
works in producing geothermal areas for the purpose of detecting
induced seismicity; federal lessees are required to cooperate with
appropriate public agencies. Where induced seismicity is determined
to present a significant hazard, the USGS may require remedial
actions on federal lands, such as reduced production rates, reduced
injection of wastes and other fluids, or suspension of production.
Federal funding of research for seismic identification and monitor-
ing is needed at a nominal level.
HYDROLOGICAL ALTERATIONS
The possible effect of geothermal development on geologic forma-
tions and their hydrologic communication has brought significant en-
vironmental concern, particularly in the proximity of Yellowstone
Park. It is suspected that geothermal development may affect sur-
face features such as hot springs, fumaroles, mud pots, and geysers
or may deplete reservoirs utilized for drinking water or agricul-
tural purposes.
There are no specific regulations controlling possible hydro-
logical alterations caused by geothermal development. However, the
National Environmental Policy Act requires evaluation of the impacts
of geothermal development on unique features, such as hot springs or
shallow ground water. Legislation requiring protection of hot
springs and hydrological evaluation prior to leasing of certain
unique lands is being proposed by state and federal governments.
If proposed legislation is enacted, hydrological evaluations
may be required of proposed geothermal development sites. The cost
of those evaluations may be significant enough to cause development
of some sites to become uneconomical. If the evaluations indicate
that a significant impact is likely, the proposed site will not be
developed. The Panel is not prepared at this time to recommend
significantly increased efforts aimed specifically at developing
predictive tools for hydrological alterations. Further study is,
however, required of the area in anticipation of future legislative
mandates.
xii
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FEDERAL FUNDING TRENDS
Aggregate federal funding for environmental controls-related
research has declined from fiscal year (FY) 1979 to FY 1980. Follow-
ing a gradual increase to slightly over $5 million in FY 1979, the
planned funding for controls-related research has dropped over 45
percent to under $3 million for FY 1980. Similarly, the federal
funding for all geothermal environmental research has dropped sharp-
ly from $9.4 million in FY 1979 to $5.55 million in FY 1980.
The Department of Energy's (DOE) funding as a fraction of total
federal spending for controls research declined from two-thirds in
FY 1979 to less than one-half in FY 1980. Other agencies sponsoring
environmental controls studies included the Environmental Protection
Agency (EPA) and the United States Geological Survey (USGS) of the
Department of Interior (DOI).
The research areas receiving greatest funding attention in FY
1978 and FY 1979 included air emissions, liquid discharges, subsi-
dence, seismicity, and hydrological alterations. The declining
federal funding for environmental controls-related research has
caused funding reductions for FY 1980 in all of these research
areas except seismicity. The most severe reduction (approximately
85 percent) has been in the area of air emissions, reflecting only
in part the completion of the government-industry costs shared EIC
H2S abatment demonstration at The Geysers. Geothermal solid
wastes have not been the object of significant federal research
between FY 1977 and FY 1980.
RECOMMENDATIONS
The Panel recommends increasing federal support for geothermal
environmental controls research in a number of specific areas, some
of which are among the most critical for geothermal commercializa-
tion. In the absence of increased federal funding, delays in com-
mercialization may result from the lack of adequate controls and
from uncertainties brought about by regulatory delay and/or revi-
sion. Equally important, without needed research, unacceptable
environmental damage may result.
The Panel concluded that several categories of environmental
concern stand out in both importance and priority for research.
These are air emissions, liquid discharges, solid wastes, and subsi-
dence. Other categories induced seismicity, hydrological altera-
tion, noise were deemed to warrant significant, but lesser,
attention in federal research programs. Industry experts consulted
by the Panel agreed with the Panel's general conclusions and most of
the Panel's specific recommendations. Where differences exist, they
xiii
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may be attributed primarily to the longer-term perspective of fed-
eral agencies with regulatory and leasing responsibilities.
Specifically, the Panel recommends:
1. Continued coordination among key federal agencies in con-
ducting controls development and other controls-related
research.
2. Government monitoring of production sites on a continuing,
cooperative basis for the purpose of developing a better
understanding of environmental concerns and controls.
3. Overall, increased federal funding for environmental con-
trols research.
4. Reordering research priorities, with enhanced funding for
several high priority controls development research areas
including:
accelerated development and demonstration of controls
for hydrogen sulfide emissions to the atmosphere from
electricity generating plants
accelerated development and demonstration of H2$ steam
stacking and well emissions control
characterization and development of controls, where
necessary, for emissions to the atmosphere of other
(non H2S ) substances
development and demonstration of viable injection moni-
toring systems for liquid discharges
research into the treatment and use of nongeo thermal
waters for injection to prevent subsidence and reser-
voir depletion
characterization of solid wastes from geothermal
energy production
evaluation of available control (disposal) methods for
solid residuals, whether hazardous or nonhazardous in
nature
development of alternative subsidence prediction, con-
trol, and prevention methods.
xiv
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5. Moderate efforts in several environmental controls re-
search areas including:
development of brine treatment technologies
development of in-line monitoring devices to measure
fluid characteristics at various points in the fluid
distribution and conversion system
development of capability to chemically and physically
model and to stimulate geothennal fluid during produc-
tion, conversion, and injection
development of solid waste management controls, as
needed
characterization of induced subsidence
identification and characterization of induced seismi-
city
characterization (and possible control) of radionu-
clide emissions.
6. Low-level efforts in the following areas:
development of controls for induced seisraicity
development of noise controls.
xv
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1.0 INTRODUCTION
1.1 Purpose of Environmental Controls Panel
The Interagency Geothermal Coordinating Council established the
Environmental Controls Panel in 1979 to assess the adequacy of exist-
ing controls for geothermal energy systems, to review ongoing pro-
grams to develop environmental controls, and to identify areas for
enhanced or reduced federal efforts. Represented on the Panel are:
Environmental Protection Agency (EPA)
Department of Energy (DOE)
Division of Geothermal Energy (DGE)
- Office of Environment (EV)
Department of the Interior (DOI)
- United States Fish & Wildlife Service (USFWS)
- United State Gelogical Survey (USGS)
- Bureau of Land Management (BLM)
- United States Forest Service (USFS)
Department of Defense (DOD) - Navy
Department of Agriculture (DOA)
This report documents the initial conclusions and
recommendations of the Panel. It builds, in part, on an earlier
report to the IGCC titled "Environmental Research and Development
Needs to Support Federal Guidance, to the Geothermal Industry"
(February 1978) prepared by the now-defunct Environmental Subpanel of
the Resource Technology Panel.
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For the purpose of its work, the Panel has defined "controls" to
be a technological or other method to reduce, terminate, or prevent
detrimental effects on the environment. Technological controls, for
example, are being used to remove l^S from vented air emissions, to
muffle noise, and to remove contaminants from water discharges. The
Panel has also included in its review a limited number of control-
oriented support efforts (such as the definitional work in charac-
terizing solid wastes and evaluating solid waste disposal options
required to develop regulations). In addition, non-technological
control methods have been included: well monitoring, for example,
because the only known way to protect an aquifer is to cease injec-
tion when contamination or the threat of contamination is detected.
Finally, siting is included because, for example, proper location of
production facilities may prevent noise pollution from affecting
other dedicated land uses and human inhabitants.
The tasks required to fulfill the stated charter of the Environ-
mental Controls Panel are:
1) identifying the environmental concerns which may interfere
with the commercialization of geothermal energy resources
2) assessing the need for controlling the impact of these con-
cerns based on current knowledge about environmental impacts
and existing and anticipated regulations
3) assessing the adequacy of existing technological and non-
technological control techniques
4) reviewing ongoing federal research efforts
5) recommending needed modification to federal research pro-
grams to assure the availability of adequate controls on a
timely basis.
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1.2 Environmental Concerns
The major environmental concerns associated with geothermal
energy development and utilization include air emissions, liquid
discharges, solid wastes, noise, subsidence, seismicity, and hydro-
logical alterations. Each of these concerns is discussed briefly in
Section 2 of this report, together with the associated legislation
and regulations, available and potential control options, and the
Panel's conclusions and recommendations for federal research.
Section 3 of this report recommends the priorities for federal
controls research. Sixteen research areas, identified in conjunction
with industry experts, are defined and ranked in importance.
1.3 Federal Environmental Controls Budget
As part of its charter, the Environmental Controls Panel was
charged with assessing the adequacy of existing federal funding for
geothermal environmental controls-related research. The Panel has
found a significant decline in federal funding for fiscal year (FY)
1980 in both the total geothermal environmental research budget and
the envirnmental controls-related research budget.
Federal funding for geothermal environmental research for the
years FY 1977 through FY 1980 is presented in Table 1-1 and Figure
1-1. The budget amounts presented here and in later tables and
figures are estimates and can only be used to illustrate the relative
trends in federal funding. The funding trend for environmental
research in Table 1-1 and Figure 1-1 reflects a slight decline from
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TABLE 1-1
FEDERAL GEOTHERMAL ENVIRONMENTAL RESEARCH PROGRAM
BUDGET SUMMARY BY AGENCY1
(Thousands of dollars)
1977
1978
1979
1980
EPA
DO I
DOE
(USGS)
(DOE/EV)2
(DOE/ET)2
TOTAL
700
1,000
5,050
(3,700)
(1,350)
6,750
850
1,000
7,650
(4,400)
(3,250)
9,500
850
1,250
7,300
(3,400)
(3,900)
9,400
850
1,150
3,550
(2
(1
5,550
,300)
,250)
Budget figures rounded to nearest $50,000.
2
DOE/EV - Department of Energy/Environment
DOE/ET - Department of Energy/Energy Technology
u
ca
r-<
,-H
o
Q
c
o
H
t-1
H
Cd
u
a
3
ca
o
OS
1977
1978
1979
1980
FIGURE 1-1
FEDERAL GEOTHERMAL ENVIRONMENTAL RESEARCH PROGRAM
BUDGETSUMMARY
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FY 1978 to FY 1979 and Chen a sharp decline from FY 1979 to FY 1980.
The sharp decline represents a 40 percent reduction in planned
federal funding from approximately $9.4 million in FY 1979 to $5.5
million in FY 1980. Table 1-1 also shows the preeminent role of the
Deparment of Energy (DOE) in geothermal environmental research.
Similarly, Table l-II and Figure 1-2 chart a sharp decline in
federal funding for controls-related research from FY 1979 to FY
1980. This sharp decline represents a 46 percent decrease in federal
controls research from approximately $5.1 million in FY 1979 to
approximately $2.7 million in FY 1980. Table l-II also shows that
the DOE is the source of $2.25 million of the $2.35 million reduc-
tion, while the Envrionmental Protection Agency (EPA) and the United
States Geological Survey (USGS) funding of controls-related research
remained relatively constant from FY 1979 to FY 1980.
The federal funding trends for controls-related research by
environmental concern are presented in Table l-III and Figure 1-3.
Federal funding declined in FY 1980 for the environmental concerns of
air emissions, liquid discharges, noise, subsidence, seismicity, and
hydrological alterations. The most severe decline (approximatly 85
percent) is in the area of air emissions, though much of the decline
reflects completion of construction at the government-industry cost-
shared pilot plant demonstration of the EIC l-^S abatement process.
Funding in the area of liquid discharges also declines noticably
in FY 1980 by approximately 48 percent from the FY 1979 level.
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TABLE l-II
FEDERAL GEOTHERMAL ENVIRONMENTAL RESEARCH PROGRAM
CONTROLS-RELATED BUDGET BY AGENCYl
(Thousands of dollars)
1
1977
1978
1979
1980
EPA
DOI
DOE
(USGS)
(DOE/EV) 2
(DOE/ET)2
TOTAL
300
1,000
800
2,100
550
1,000
2,650
(300) (600)
(500) (2,050)
4,200
500
1,250
3,350
(200)
(3,150)
5,100
500
1,150
1,100
2,750
(300)
(800)
Budget figures rounded to nearest $50,000.
2
DOE/EV - Department of Energy/Environment
DOE/ET - Department of Energy/Energy Technology
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o
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H
W
O
CQ
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TABLE l-III
FEDERAL GEOTHERMAL ENVIRONMENTAL RESEARCH PROGRAM
CONTROLS-RELATED BUDGET BY CONCERN1
(Thousands of dollars)
Fiscal Year 1977 1978 1979 1980
Air Emissions
Control Technology Development
and Assessment 450 1,350 1,050 150
Subtotal 450 1,350 1,050 150
Liquid Discharges
Model Development 50 50 100
Underground Monitoring 150 150 150 150
Control Technology Assessment 300 400 250 300
Containment Cement Development - 700 600
Subtotal 450 1,300 1,050 550
Solid Wastes
Characterization 50
Disposal Technology
Assessment
Subtotal 50
Noise
Control Technology Assessment 50 50 100 50_
Subtotal 50 50 100 50
Subsidence
Predictive Model Development 250 1,100 500
Site Monitoring2 1,050 100 50 150
Control Development -
Subtotal 1,050 350 1,150 650
Seismicity
Site Monitoring 100 450 550 500
Control Assessment and
Development _- 50 450 250
Subtotal " 100 ' 500 1,000 750
Hydrological Alterations
Predictive Model Development 100 100 100
Site Measurement 550 650 450
Subtotal 650 750 550
TOTAL 2,100 4,200 5,100 2,750
Budget figures rounded to nearest $50,000.
USGS seismic monitoring networks are initially for resource charact-
erization purposes. Upon completion of the resource evaluation, the
networks are used for environmental monitoring.
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2,000
ca
H
M-I
O
c
oj
to
3
O
H
w
D
ps
1,500
1,000 ~
500-
77 78 79 80
Air
Emissions
77 78 79 80
Liquid
Discharges
77 78 79 80
Solid
Wastes
77 78 79 80
Noise
77 78 79 80
Subsidence
77 78 79 80
Scismicity
77 78 79 80
HydroJogical
Alterat ions
FIGURE 1-3
FEDERAL GEOTHERMAL ENVIRONMENTAL RESEARCH PROGRAM
CONTROLS-RELATED BUDGET BY CONCERN
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Funding for seismicity controls research is reduced 25 percent be-
tween FY 1979 and FY 1980. Funding for noise control research de-
clined by 50 percent between FY 1979 and FY 1980, although the level
of support is very low. Table l-III also shows almost no federal
support for the area of solid waste characterization and control, an
area of great environmental concern.
In short, the Panel found the federal funding trends for overall
geothermal environmental research, controls-related research, and six
of the seven environmental concerns research to be declining sharply
from FY 1979 to FY 1980. In addition, the areas of air emissions and
liquid discharges have declining budget trends starting in FY 1978.
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2.0 ENVIRONMENTAL CONCERNS, ASSOCIATED LEGISLATION AND REGULATIONS,
AND CONTROL OPTIONS
This section discusses the Panel's review of the status of, and
relationships between 1) each major category of environmental concern
for which control methods may be needed, 2) pertinent regulations
and/or legislation under which regulations may be anticipated, and 3)
control options, whether available, under development, or in need of
development. Seven sections follow which address:
Air Emissions
Liquid Discharges
Solid Wastes
Noise
Subsidence
Seismicity
Hydrological Alterations.
The dynamic state of the geothermal energy industry made the
Panel's evaluation extremely difficult. At this time, geotherraal
energy production is concentrated at a unique resource: the steam-
dominated field at The Geysers in California. The extent to which
environmental problems at The Geysers are typical of those at liquid-
dominated sites is questionable. Similarly, the transferability of
controls from The Geysers has not been fully established. Later, the
extraction of Gulf Coast geopressured resources will present addi-
tional environmental concerns.
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The site specificity of environmental factors compounded further
the task of assigning relative priorities to environmental concerns
and, then, to research areas. Researchers have expanded the list of
environmental concerns over the past several years, and are finding
that the relative dimensions of the concerns vary widely from site to
site. For example, intrusion of injected fluids into high quality
aquifers appears improbable in the Imperial Valley, but is a major
concern in the highly-fractured Raft River (Idaho) geothermal zone.
Federal environmental regulations have not been developed for
all the major categories of environmental concern. And one regula-
tionthe application of prevention of significant deterioration
(PSD) to H2S emissionswill be amended in response to a court de-
cision. State and local regulations vary, and are often more strin-
gent than their federal counterparts. Adequate data bases are the
foundation for reasonable regulations in all areas of concern, yet
they are completely absent in the case of geothermal solid wastes.
Several federal laws exist which may affect the siting of geo-
thermal energy facilities. These include the Coastal Zone Management
Act, the Wetlands Protection Act, the Historical Preservation Act,
the Endangered Species Act, the Floodplain Management Act, the Rivers
and Harbors Act, the National Environmental Protection Act, and the
Geothermal Steam Act. In general, these laws impose anticipatory
controls on geothermal development in that they affect the siting of
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energy facilities and do not require remedial application of control
methods.
2.1 Air Emissions
Problem
Hydrogen sulfide (E^S) has been and remains a major environ-
mental concern of geothennal energy development. The offensive
nature of H^S odor is a greater cause of concern than its toxicity
at the observed levels of concentrations of geothermal sites.
Concentrations.in air of 30 parts per million (ppm) or above are
toxic while the odor threshold is only 0.0007-0.0032 ppm.
In the few states where H2S standards exist, they are ambient
standards based upon odor rather than known health or ecological
effects. The standards are not uniform, varying from 0.003 ppm
(1-hour average) in most of New Mexico to 0.03 ppm (1-hour average)
in California. There is no federal l^S ambient standard and this
has led to the development of diverse state standards.
The problem of l^S emissions from geothermal operations origi-
nated and continues to be focused at The Geysers power generation
site in Northern California. The state ambient standard of 0.03 ppm
has been translated into allowable emissions that will be increasing-
ly restrictive as generating capacity expands. The problem is com-
pounded at The Geysers by the fact that the first 500 megawatts (MW)
of generating capacity was built without f^S controls and thus has
required retrofitting.
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Sources of J^S emissions include well drilling, venting and
cleanout, power plane operation, and steam stacking. Steam stacking
occurs during plant shutdowns at vapor-dominated (steam) resources.
In general, power plant emissions are the most significant source of
H2S, with steam stacking second, and miscellaneous well emissions
last.
It is expected that l^S emissions will necessitate control at
many, if not most, geothermal development sites, although it appears
that the quantities emitted will vary greatly from site to site.
Most cases will differ from The Geysers in that other resources are
liquid-dominated rather than vapor-dominated (steam). If liquids are
flashed, as is expected in most developments, then t^S controls
developed for The Geysers situation may be applicable to the steam
fraction. On the other hand, control options may be broadened for
liquid-dominated resources by offering the opportunity to treat the
liquid stage before flashing. If the liquid is not allowed to flash
during heat transfer, the opportunity also exists for closed-cycle
operation (i.e., injecting the liquid back to the reservoir with
little or no emission of gases).
Other substances may be emitted to the atmosphere during geo-
thermal operations. These substances include carbon monoxide (CO),
ammonia (Nl^), radon, hydrocarbons, mercury vapor, and boron. All
of these originate as components of the geothermal reservoir fluid.
None has yet been shown to be of environmental significance, but the
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possibility exists, particularly for those that may be considered
hazardous, such as radon and mercury.
Regulations
The principal authority for regulation of air pollution is the
Federal Clean Air Act, as amended by the Clean Air Act Amendments of
1977. In general, the Clean Air Act regulations are implemented by
the states through State Implementation Plans required by the Act and
approved by the Environmental Protection Agency.
Sections of the Clean Air Act that may have impacts upon geo-
therraal development are:
Section 107 - State establishment of Air Quality Control
Regions; EPA establishment for interstate regions.
Section 108 - EPA Publication of air quality criteria.
Section 109 - EPA promulgation of national primary and secon-
dary ambient air quality standards (now includes particu-
lates, sulfur dioxide, nitrogen oxides, hydrocarbons, ozone,
lead, and carbon monoxide); standards are effects-based.
Section 110 - States establish implementation plans to meet
standards; plans may include source emission limits.
Section 111 - EPA establishment of New Source Performance
Standards (emission limits) for any pollutant for specific
stationary sources, standards are technology-based. States
must then establish emission limits for same constituents
from existing sources.
Section 112 - EPA establishment of emission standards for
hazardous air pollutants for specified sources; mercury,
asbestos, beryllium, and vinyl chloride standards now exist
for certain sources; none yet for geothermal.
Section 122 - EPA must specifically review and may regulate
radioactive pollutants, cadmium, arsenic, and polycyclic
organic matter.
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Sections 160-169 - establishes requirements to prevent signi-
ficant deterioration of air quality in clean air areas.
Section 169A - EPA establishes requirements toward remedying
visibility impairment in Federal Class I areas where visibil-
ity is an important value.
EPA currently has no plans to add any of the known geothermal
air pollutants to the list of criteria pollutants and, hence, to
establish a national ambient air quality standard for any of them.
However, a state may add geothermal air pollutants to its list of
controlled pollutants as some have already done for hydrogen sulfide.
These states include, California, New Mexico and Hawaii.
EPA may develop New Source Performance Standards (NSPS) for
hydrogen sulfide and perhaps other emissions from geothermal opera-
tions. Any geothermal power plant that would have the potential to
emit 250 tons or more of H2S per year would have to meet the permit
requirements of EPA's existing regulations for the prevention of
significant deterioration (PSD). This including, in most cases, a
requirement for the application of best available control technology
(BACT). In response to a recent court decision, however, EPA has
proposed comprehensive amendments to the PSD regulations (see 44 FR
51924, September 5, 1979). Among them is a provision that would in
effect exempt from the BACT requirement, as well as other PSD
requirements, any source that would emit only non-criteria pollutants
in major amounts (44 FR 51953-54 § 52.21 (i)(g)). A geothermal power
plant would emit only ^S, a non-criteria pollutant in major
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amounts, if current indictions hold true. Whether EPA will make that
provision is as yet uncertain.
Status of Controls
Among geothermal air emissions, only hydrogen sulfide has been
of sufficient concern to date, to require control. So far, there is
no evidence to indicate that other air pollutants will require con-
trol.
Virtually all of the pilot or full-scale demonstrations of geo-
thermal H^S removal technology have been at The Geysers power gen-
eration site. Several bench-scale development efforts are being
carried out there and elsewhere. Of the demonstrated technologies,
three show promise for commercial scale application. These are:
Iron catalyst process
Stretford process
EIC process (developed by the EIC Corporation)
The iron catalyst and Stretford processes are "downstream" technolo-
gies, meaning they are applied to the turbine exhaust. The EIC pro-
cess is applied to the raw steam "upstream" or ahead of the turbine.
Upstream technologies have the advantages of 1) being able to con-
trol emissions during steam stacking (the process of venting the
steam flow during power plant shutdown), 2) reducing the corrosivity
of the steam to turbine blades and other power plant components, and
3) being able to control ammonia and boron emissions.
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The Stretford process is applied to the noncondensible gas ejec-
tor stream from a surface condenser. The stream is scrubbed with a
regenerable aqueous solution containing sodium carbonate, sodium
metavanadate, and anthraquinone disulfonic acid. Pure sulfur is pro-
duced by the process. A drawback of the process is that, although it
can remove virtually all l^S that it contacts, it cannot treat the
H2S dissolved in the condensate. This portion will be emitted at
the cooling tower unless treated. It was originally thought that
this would constitute less that 20 percent of the total l^S, but in
practice it appears that it may be up to 40 percent. Thus, the con-
densate may also require treatment, perhaps with hydrogen peroxide.
The iron catalyst system has been applied at The Geysers to the
older units with direct contact condensers. Ferric sulfate is added
to the condensate cooling water, oxidizing the l^S contained in the
aqueous phase. The noncondensible gases are ducted into the cooling
tower and scrubbed by the falling water. Ferric ions are regenerated
and sulfur is produced. However, the sulfur sludge is impure and
presents a toxic solid waste problem. The t^S removal efficiency
for the iron catalyst system has been low (around 60 percent), but it
has been improved to greater than 90 percent by adding hydrogen per-
oxide and sodium hydroxide to the process.
The EIC process is the only demonstrated process whose develop-
ment has been supported, in part, by government funding. The recent-
ly completed one-tenth scale demonstration at The Geysers was very
18
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successful, removing more than 95 percent of the t^S from the raw
steam. The steam is scrubbed with copper sulfate to produce copper
sulfide and ammonium sulfate. Copper sulfate is regenerated from the
copper sulfide and the cleaned steam is sent to the turbine.
There is no certainty that any of the above technologies will be
consistently successful and/or economical in all applications. A
central question is how easily the processes being tested on vapor-
dominated resources can be transferred to the more prevalent
liquid-dominated resources. For that reason, other ^S removal
technologies are being examined. Some of these are:
electrochemical oxidation (brine)
Dow oxygenation process (brine)
activated carbon/metal catalyst (brine/steam).
Conclusions and Recommendations
Hydrogen sulfide has been and remains a major environmental con-
cern of geothermal energy development and utilization. It is recog-
nized as a leading concern by both government and industry experts.
The concern has been significant enough to interfere with geothermal
development and expansion at some sites. Several states, including
California, New Mexico, and Hawaii, have established ^S ambient
standards. However, existing control technology has not been demon-
strated to consistently meet these standards and federal funding for
research, development, and demonstration of new methods has faded.
The problem is potentially a major barrier to geothermal development.
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The apparent reliance in the federal program on the EIC process for
an ultimate solution is both premature and unwise.
Although the Panel recognizes that private industry will con-
tribute to the improvement of l^S control technology, the Panel
recommends that the federal government support, at a significantly
increased level, research, development, and accelerated commercial
demonstration of control technologies for:
power plant emissions
steam stacking and well emissions.
In addition, non-I^S air emissions should be characterized and con-
trols developed where necessary.
2.2 Liquid Discharges
Problem
The waste waters from geothermal operations that will be of the
greatest environmental concern will be spent "brines" (the geotherraal
fluid from which heat has been removed). Of lesser concern will be
condensate/cooling water, site runoff, and sanitary waste.
Spent brines and condensate that contain contaminants (e.g.,
dissolved metals) in potentially harmful quantities are likely to be
subsurface-injected. Even if they are not environmentally harmful,
they may be injected back to the reservoir as insurance against sub-
sidence and reservoir depletion.
In some, perhaps many cases, spent geothermal brines may be sur-
face-discharged. Circumstances conducive to surface discharge are:
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high water supply demand in arid areas
relatively high quality of geothermal water compared to
surface water
high cost of injection
relatively low volume of waste water, such as in non-electric
applications.
It also may be expected that runoff and sanitary waste waters associ-
ated with geothermal operations would remain in the surface water
domain.
The environmental concern, is probably greatest from injection
with its potential for waste water migration or leakage to aquifers
supplying water for drinking and other uses. The premise here is
that, unlike surface water contamination, pollution of an aquifer may
be permanent and virtually noncorrectable once it has occurred. The
potential danger is compounded by the fact that geothermal reservoirs
are characteristically (except for the Gulf Coast geopressured zone)
in geologically unstable areas where natural conduits, such as faults
and fractures, are common.
Another important consideration in geothermal injection is that
the quantities of injected water, particularly from power generation
sites (or methane extraction sites in the geopressured case), will be
enormous. Those quantities may be orders of magnitude greater than
those of past experience, in oil and gas fields, for example.
Surface discharges of spent geothermal fluid pose the potential
for surface water pollution from the natural constitutents in the
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fluid and any added materials. The potential problems from the spent
waters, runoff and sanitary wastes might be similar to those of an
inorganic chemicals plant discharging to surface waters.
Regulations
The principal federal law governing water quality is the Federal
Water Pollution Control Act Amendments of 1972. The law primarily
protects surface waters by way of permits under the National Pollu-
tion Discharge Elimination System (Section 402). Adminstration of
the System is by the states, upon EPA authorization. Industry-
specific Effluent Guidelines may be promulgated under Sections 304
and 306. Permit conditions may then be based upon those guidelines.
More restrictive permit conditions may be imposed based upon receiv-
ing Water Quality Standards (Section 303), if the technology-based
Effluent Guidelines will not be sufficiently protective of receiving
waters.
The Federal Safe Drinking Water Act mandated the establishment
of an Underground Injection Control Program, also to be administered
by the States, to protect drinking water aquifers. This program will
also require injection permits whose issuance is based upon a prior
analysis of the planned injection and an encompassing area of review
for geological, hydrological, and man-made influencing factors. Well
construction and monitoring requirements are prescribed. The regula-
tions are now in the proposal stage.
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Status of Controls
Treatment technologies now exist to remove almost any constitu-
ent from waste water. With little modification, experts feel exist-
ing technologies can be transferred to the treatment of geothermal
waste waters. Lower cost technologies such as chemical precipitation
and flocculation, sedimentation, and filtration, generally are most
useful in removing suspended materials. These are the technologies
most likely to be used for treating geothermal waste waters. These
technologies may be used prior to surface disposal of relatively high
quality spent fluids or may be used to treat water prior to injection
to prevent potential plugging of the injection system.
More sophisticated technologies that will remove dissolved salts
characteristic of geothermal brines are typically expensive. For the
large volumes of waste water associated with geothermal power produc-
tion, the costs may be prohibitive. Such technologies include forced
evaporation, ion exchange, reverse osmosis, and electrodyalysis.
Only where mineral recovery may be profitable or where water for
other uses is at a high premium are these technologies expected to be
viable for geothermal operations.
Conclusions and Recommendations
Preventing contamination of both surface and subsurface water
resources from brine injection or surface disposal represents a major
concern of geothermal energy development and utilization in the eyes
of both government and industry experts. Adequate waste water
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treatment technologies appear to be generally available, but, beyond
primary treatment, may be too costly to be applied widely. It is
more important to develop high rate injection technologies and moni-
toring techniques for injection that will ensure confinement of
fluids that are environmentally harmful for very long periods.
Planned federal funding for FY 1980 is at a very low level for
waste water controls and for injection monitoring system development.
The Panel recommends that the federal government assign high priority
and enhanced funding to research on:
Injection monitoring techniques
Treatment and use of nongeothermal waters for injection to
prevent subsidence and reservoir depletion.
The Panel further recommends that research support be provided to:
Brine treatment
In-line monitoring techniques
Chemical and physical modelining/simulation techniques for
predicting characteristics of brine constituents.
2.3 Solid Wastes
Problem
Solid wastes from geothermal operations are likely to be com-
prised mainly of the residual sludges of air and water treatment,
scale from cleaning the fluid distribution and conversion networks,
and the cuttings and drilling muds from production and injection well
drilling. Any or all of these wastes may in the future be classified
as hazardous on the basis of hazardous waste criteria. If the wastes
24
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are determined to be hazardous they will be subject to restrictive
regulations. The pollutant constituents in the treatment sludges
will include metals, sulfur, and other inorganic materials from the
geothermal fluid, plus treatment chemicals that may be added to aid
energy extraction and reduce equipment deterioration. Drilling
wastes will include rock cuttings and a variety of chemical materials
in drilling muds.
The potential volume and characteristics of geothermal solid
wastes are now largely unknown, although it is anticipated that very
high generation rates will occur at some sites. Thus, the extent of
the problem will not be known until adequate characterization studies
are completed.
Regulations
The authority for federal control of solid wastes, both hazard-
ous and nonhazardous, is the Resource Conservation and Recovery Act
(RCRA) of 1976. Hazardous waste regulations were proposed in
December 1978 regarding 1) the identification and listing of
hazardous wastes, 2) standards applicable to generators of hazardous
waste, and 3) performance standards for hazardous waste management
facilities. Final regulations applicable to generators and trans-
porters of hazardous wastes and also for notification of hazardous
waste activity were recently published. Congress is currently tempo-
rarily excluding geothermal solid wastes from control under the
hazardous waste regulations while EPA makes a study to determine
25
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whether these wastes are hazardous, how to manage them, and the costs
of waste management. If geothennal wastes are determined not to be
hazardous, their disposal will be regulated as nonhazardous solid
wastes under Section 4004 of the Resource Conservation and Recovery
Act, to be implemented by the individual states.
Authority for control of toxic materials in drilling muds may
exist at the federal level in the Toxic Substances Control Act. In
addition, several states now have regulations controlling solid waste
disposal. California, for example, considers geothermal solid wastes
as toxic, requiring their containment in an impervious secured land-
fill with leachate monitoring and treatment.
Status of Controls
Methods, such as secured landfills, are available for managing
solid wastes, including hazardous wastes. Evaluations have not been
conducted on management options for geothermal wastes, however, and
waste characterizations (which precede disposal evaluations) have not
been undertaken. Following the completion of evaluations, management
technology will be prescribed in solid waste management regulations.
One of the main problems may be to find acceptable disposal sites
within a reasonable distance from the geothermal operation. Waste
management may be very costly for geothermal operations, particularly
if the wastes are determined to be hazardous and disposal sites are
not readily accessible.
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Conclusions and Recommendations
Solid wastes from geothermal energy development and utilization
have not been adequately characterized. Until characterizations have
been completed, definitive evaluations of solid waste management op-
tions are impossible. With the commercialization of liquid-dominated
resources looming (these resources could generate large amounts of
solid wastes), the Panel concludes that solid wastes bear a high pri-
ority and recommends greatly enhanced efforts to characterize them
and to evaluate management options. The recommended study should
include the following tasks and be performed from FY 1980 to FY 1982:
1) define physical and chemical characteristics of geothermal
solid wastes
2} evaluate the applicability of current waste management prac-
tices to geothermal wastes
3) consider health and environmental effects of each management
procedure
4) evaluate cost ($/ton) of each waste management procedure
5) recommend measures to adequately manage these solid wastes.
2.4 Noise
Problem
Well drilling and testing, steam venting and plant operation are
the major sources of noise pollution. Well drilling and steam vent-
ing represent the greatest noise problems of geothermal development.
Noise produced during system testing and venting originates from the
direct escape of geothermal fluid from wellheads, separators, vents
and bypasses in the fluid distribution system. The frequency of
27
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system testing or venting may decrease after the plant becomes opera-
tional. These noise sources will not cease, however, because addi-
tional wells must be drilled to support a level of energy production
over the lifetime of a field.
Noise pollution presents a relatively minor problem to geother-
mal energy development when compared with air pollution, water pollu-
tion, and solid waste. However, noise pollution can be significant
enough to affect siting decisions for geothermal facilities.
Regulations
The Noise Control Act of 1972 provides for federal regulatory
authority over noise from aircraft, railroads, construction and
transportation equipment, motors, engines, and electrical or elec-
tronic equipment. Control of noise pollution from other sources is
generally left to state and local governments. However, the Act en-
courages federal agencies to limit noise levels at federal facilities
and authorizes EPA to coordinate those efforts. The U.S. Geological
Survey, for example, limits noise from geothermal operations on fed-
erally leased land to 65 decibels-A scale (dBA) at the lease boundary
or one-half mile from the sound, whichever is greater. In addition,
the Occupational Safety and Health Administration (OSHA), although it
does not actually limit the noise source, specifies that no worker be
subject to 115dBA noise for more than 15 minutes or to 90dBA noise
for more than eight hours, without ear protection.
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Status of Controls
Control of noise pollution from geothermal sites may be accomp-
lished by prevention, shielding, or attenuation of the noise. There
are numerous types of noise abatement equipment which can be in-
stalled relatively inexpensively. These include rock-filled or
water-filled chambers, baffled sound-absorbent mufflers, and large
twin-cylinder centrifugal expansion towers. Noise pollution can also
be alleviated by careful siting, or keeping the site away from the
affected population.
Conclusions and Recommendations
Noise abatement equipment exists that can adequately control the
noise generated by geothermal energy development. This equipment can
range from simple shielding techniques to sophisticated centrifugal
expansion towers, but in either case, the equipment cost is small
compared to other pollution abatement equipment.
The proposed federal budget allows for $50,000 for noise control
technology development in FY 1980. Additional research efforts for
noise control are not recommended by the Panel.
2.5 Subsidence
Problem
Subsidence or sinking of the land may be caused during geother-
mal energy development by removing large amounts of fluid from the
ground. Subsidence presents a major concern where the topography of
the neighboring land is very level, where bodies of water may be
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affected, or where there are nearby surface improvements. For exam-
ple, a small amount of subsidence in the Imperial Valley may cause
major irrigation and drainage problems. However, subsidence in
naturally hilly locations may cause only minor or insignificant prob-
lems.
The amount of subsidence that occurs when a given volume of
fluid is withdrawn and not replaced is dependent upon the geological
formations in the area of the site. If the surface land is supported
in part by fluid, subsidence will be greater than in areas where the
surface is totally supported by rock formations.
Subsidence could present a major concern if geopressured resour-
ces near the Gulf Coast are utilized because a large amount of land
near this region is presently only a few feet above sea level.
Regulations
For geothermal developments on leased federal lands, USGS
Geothermal Operations Order No. 4 states: "Surveying of the land
surface prior to and during geothermal resources production will be
required by the (United States Geological Survey (USGS)) for
determining any changes in elevation (on and around) leased (federal)
lands. Lessees shall make such resurveys as required by the (USGS)
to ascertain if subsidence is occurring. Production data, pressures,
reinjection rates, and volumes shall be accurately recorded and filed
monthly with the (USGS). In the event subsidence activity results
from the production of geothermal resources, as determined by surveys
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by the lessee or a governmental body, the lessee shall take such
mitigating actions as are required by the lease terms and by the
(USGS).
If subsidence is determined by the (USGS) to present a
significant hazard to operations or adjoining land use, remedial
action may be required, including, but not limited to, reduced
production rates, increased injection of waste or other fluids, or a
suspension of production."
Status of Controls
Only two approaches, or a combination of them, are available to
control subsidence from geothermal fluid extraction. The first
approach is to monitor the land near the sites and reduce or termi-
nate production if significant subsidence occurs. The second
approach is to inject the geothermal fluid that was withdrawn from
the reservoir. In most cases, injection may be the more appropriate
environmental cleanup approach because it involves the disposal of a
major source of the air, water, and land pollution from geotherraal
energy systems. If injection is used to prevent subsidence, nearby
high quality aquifers will have to be monitored to protect them from
contamination by the injected fluid. A more detailed discussion of
the problems of injection with respect to water quality was presented
in Section 2.2, Liquid Discharges.
Conclusions and Recommendations
In most cases, subsidence will not be a major concern of geo-
thermal energy development. The lack of adequate characterization
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and prediction measures, however, may prevent utilization of
resources at sites where other land uses would be affected. The
Panel concludes, accordingly, that subsidence characterization
prediction and control retain a high priority for research.
The federal government is currently supporting both site moni-
toring and predictive model development for subsidence. This support
should be increased to include research of subsidence characteriza-
tion, prevention and control methods.
2.6 Seismicity
Problem
Many geothermal resources are located in regions with a high
frequency of naturally occurring seismic events. There has been
concern expressed as to whether the withdrawal and/or injection of
geothermal fluids may enhance the rate of microseismic events or even
trigger a major earth movement. Studies have shown that high pres-
sure injection of large volumes of geothermal fluid can increase the
frequency of microseismic events. However, it is not known what
pressures and volumes are required to increase the frequency of
events or whether a significant tectonic release can result from the
lubrication of a major fault.
Regulations
The installation of seismographs or other instruments in pro-
ducing geothermal areas for the purpose of detecting potential
seismic activity may be initiated from time to time by appropriate
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public agencies. For geothermal developments on leased Federal land,
the USGS Geothermal Resource Operations Order No. 4 states: "Where
induced seismicity caused by the production of geothermal fluids on
leased federal lands is determined to exist, the (USGS) may require
the lessee to install such monitoring devices as necessary to
adequately quantify the effects thereof. If induced seismicity is
determined to represent a significant hazard, remedial actions may be
required by the (USGS), including, but not limited to, reduced
production rates, increased injection of waste or other fluids, or
suspension of production."
Status of Controls
There are two approaches that can be taken to minimize the
probability of significant seismic activity caused by geothermal
energy development. The first involves careful site selection,
either avoiding major faults or locating at sites that have the least
likelihood of enhancing seismicity. This task can be aided by
performing extensive geological surveys and raicroseismic studies of
the proposed sites.
The second approach to minimize induced seismicity is to monitor
the geothermal area and stop production or injection if it is shown
that geotherraal production has caused unacceptable seismic activity.
This approach involves making baseline measurements for several years
of naturally occurring seismic events in terms of depth of earthquake
foci, duration of event, force of event, and frequency of events.
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Once these data are obtained, seismic activity during geothermal pro-
duction can be compared to naturally occurring events and the source
of the activity can be evaluated. If it is shown that the source is
the geothermal production, then production can be reduced or stopped,
or injection techniques modified (i.e., altering flow rate and/or
pressure).
Conclusions and Recommendations
Geothermal energy development has not been shown to be a contri-
butor to significant earthquake activity in the U.S. It is not cer-
tain that this record will continue, as significant development has
not yet occurred in earthquake-prone areas. It has been shown (e.g.,
at The Geysers) that geothermal production may cause an increased
frequency of minor seismic events. Even this enhanced microseismi-
city may be reduced by careful site selection, and the chance of a
significant earth movement can probably be reduced by monitoring and
production curtailment techniques. In short, in most cases, concern
of induced seismicity should not present a major obstacle to the
commercialization of geothermal resources.
The federal funding for geothermal related seismic research is
approximately one million dollars for FY 1979 and $750,000 FY 1980.
The Panel feels that continued funding at the 1979 level should be
maintained to adequately identify and characterize induced seismicity
and to evaluate control techniques.
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2.7 Hydrological Alterations
Problem
Possible detrimental effects of geothermal energy development on
geological formations and hydrological communication between them
represents an environmental concern that, if unattended, may retard
or prevent the commercialization of some geothermal resources. It is
suspected that geothermal development may effect surface features
such as hot springs, fumaroles, mud pots and geysers or may deplete
reservoirs utilized for public water supply, agricultural, recrea-
tional, and many other purposes. Significant environmental concern
for possible hydrological alterations caused by geothermal develop-
ment have been expressed for the Island Park area adjacent to
Yellowstone National Park as well as Mammoth Park, Mono-Long Valley,
and Volcanic Park.
Deep ground water systems associated with geotherraal resources
are complex and largely unknown. Interconnections between geothermal
resources and surface features are difficult to understand or even
identify. Studies of these systems require drilling of shallow
and/or deep wells and relatively large financial investments. In
spite of the costs involved, research and study are essential if
proper leasing decisions or drilling strategies are to be made.
Regulations
The Underground Injection Regulations, by preventing injection
to certain aquifers and allowing it to others, may have a significant
effect on subsurface water movement in public water supply areas.
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Otherwise, specific regulations do not exist for controlling hydro-
logical alterations (e.g., changes in pressure head, temperature,
water quality, and natural discharges) resulting from geothermal
development, particularly from fluid. Some areas with significant
geothermal surface features, such as Yellowstone National Park and
Mt. Lassen National Park, are stated as being off-limits to develop-
ment under the Geothermal Steam Act. In addition, the National
Environmental Policy Act requires evaluation of the impacts of
geothermal development on unique features, such as hot springs or
shallow ground water. Additional legislation requiring hydrological
evaluation prior to geothermal development near certain unique lands
and protection of hot springs are being proposed by federal and state
governments.
Status of Controls
As in the case of subsidence or seismicity, the only approaches
available to control hydrological alterations are siting and monitor-
ing in conjunction with possible termination of operations. Where
geotherraal development is likely to have unacceptable adverse effects
on hot springs, geysers, or other surface indicators of geothermal
resources, the land should be excluded from federal leasing. If
leasing is permitted, hydrological studies may be conducted to
determine well location of least impact and monitoring wells may be
drilled to aid prediction of significant alterations in the hydrolo-
gical system.
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Conclusion and Recommendations
If proposed legislation is enacted, federally supported hydrolo-
gical evaluations may be required of proposed geothermal development
sites. The cost of these evaluations may be very high at some sites,
The panel is not prepared at this time to recommend significant-
ly increased efforts aimed specifically at developing predictive
tools for hydrological alterations. Further study is, however,
required in anticipation of future legislative constraints.
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3.0 RECOMMENDATIONS OF THE ENVIRONMENTAL CONTROLS PANEL
3.1 Priorities for Research in Environmental Controls
In its review of geothermal environmental concerns, legislative
and regulatory ramifications, and control technologies or methods,
the Environmental Controls Panel identified 16 control-related
research areas; at least some research is underway in nearly every
area. A process was established for evaluating the relative
significance of the 16 research areas to the availability of controls
for geothermal energy systems. The views of several industry experts
were solicited in addition to those of government experts on the
Panel.
The 16 control-related research areas identified by the Panel
extend beyond the several control technology categories. Included as
well are control-related methods or devices (such as injection well
monitoring), modeling and simulation techniques, and residuals
characterization and control methods assessment (such as needed for
promulgation of reasonable solid waste regulations).
The 16 research areas are presented in Table 3-1 according to
their respective category of environmental concern. No research
areas have been identified for hydrological alterations.
The Panel, working with several experts from industry, evaluated
the relative priorities of the identified control-related research
areas. To aid its deliberations, the Panel applied a modified Delphi
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TABLE 3-1
CONTROL-RELATED RESEARCH AREAS
BY GEOTHERMAL ENVIRONMENTAL CONCERN
Air Emissions
H2S Controls for Power Plants
H2S Steam Stacking and Well Emission Controls
Characterization and Controls for Non-^S Air Emissions
(Boron, Ammonia, Carbon Monoxide, Hydrocarbons, Mercury and
Arsenic)
Controls for Radon
Liquid Discharges
Injection Monitoring Systems
Controls for the Treatment and Use of Non-Geothermal Waters
Brine Treatment
Chemical and Physical Modeling/Simulation Techniques
In-line Monitoring
Solid Wastes
Solid Wastes Characterization and Management Methods
Evaluation
Solid Waste Management Methods Development
Noise
Noise Control
Subsidence
Subsidence Prevention, Predicition, and Control
Induced Subsidence Characterization
Seismicity
Induced Seismicity Identification and Characterization
Induced Seismicity Controls Development
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technique Co rank Che lisCed research areas. The criceria ucilized
in the ranking exercise are presented below:
Availability of adequaCe controls
Requirements for controls under existing/pending regulations
Cost to develop conCrols
"Visibility" (i.e., public perception of the significance of
an environmental concern)
Timing of affected sites
Cost of control
Megawatts affected
Number of sites affected
Repairability of environmental effect
Severity of environmental impact
Later, the Panel relaxed its numerical ranking in favor of
categorizing the research areas into three groups: "top", "medium",
and "bottom" priority. The results of this grouping are presented in
Table 3-II. The research areas deemed to be highest priority
included certain aspects of air emissions, liquid discharges, sub-
sidence, and solid wastes. The Panel recommends that enhanced
funding be provided to each of these areas except methods for
subsidence prevention, prediction and control.
Of the seven research areas considered highest priority,
development of controls for hydrogen sulfide emitted from normal
power plant operations, steam stacking, and miscellaneous well
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TABLE 3 -I I
PRIORITIES FOR ENVIRONMENTAL CONTROLS RESEARCH
Top Group
Hydrogen Sulfide Controls for Power Plants
Injection Monitoring
Hydrogen Sulfide Steam Stacking/
Well Emissions Controls
Solid Waste Characterization and
Management Evaluation
Gaseous Emissions Characterization and
Development of Controls
Treatment and Use of Nongeothermal Waters
Methods for Subsidence Prevention, Prediction
and Control
Middle Group
Brine Treatment
In-line Monitoring
Chemical and Physical Modeling/Simulation
Techniques
Solid Waste Management Technology Development
Induced Seismicity Identification and
Characterization
Induced Subsidence Characterization*
Bottom Group
Induced Seismicity Controls
Noise Controls
*Injection Technology-related
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emissions was consistently mentioned as bearing a high priority.
Non-hydrogen sulfide emission controls (other than for radon) were
also rated in the most critical group.
Three of the top areas involved treatment and disposal of
geothermal waters and nongeothermal makeup waters. Specifically,
development of methods for injection monitoring, techniques for the
treatment and use of nongeothermal waters as makeup in reinjection
programs, and control methods for reducing the risk of subsidence are
included in the top priority group. (The importance of improved
injection technology for the disposal of spent fluids was also noted
by the Panel.) The characterization of solid wastes and the evalua-
tion of methods for proper management of hazardous constituents were
included in the top priority group.
There was a clear consensus that several research areas receive
low priority for federal funding. Included in the bottom group by
the Panel are seismicity controls (on the basis that the best control
is avoidance) and noise controls (on the basis that adequate muffling
devices are available). A seventeenth research area, flow test re-
siduals controls, was considered and rejected by the Panel. The
Panel felt that control during the flow tests can be handled by
available techniques for solids and liquids or will be of such short
duration that control is unnecessary.
The remaining, middle priority, group includes brine treatment,
in-line monitoring, chemical and physical modeling/simulation
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techniques, solid waste management, radon controls, and seismicity
and subidence characterization.
It should be noted that the Panel ascribed a moderate priority
to a few areas considered to be less important by some industry
experts. These are radon control and seismicity and subsidence char-
acterization. These differences are not viewed by the Panel as a
major cause for alarm. Neither the Panel nor industry felt any of
these areas are high priority items, and neither the Panel nor indus-
try urged that no consideration be given these areas. The Panel's
recommendation that somewhat greater attention be given these areas
may be attributed to the Panel's longer time horizon and to its
penchant for comprehensiveness.
3.2 Other Recommendations
The Panel recommends that federal research on environmental con-
trols for geothermal energy systems be closely coordinated on a
interagency basis. The need for this is aparent when the disparate
roles of various government agencies are considered:
Environmental Protection Agency: Establishes programs,
policies, and regulations to protect the environment
Department of Energy: Conducts research on all aspects of
geothermal energy commecialization activities including com-
pliance with legislative environmental mandates, and leasing
of potential geothermal lands
Department of Interior: Conducts leasing and lease manage-
ment programs for geothermal resources, protects or maintains
fish and wildlife, national parks, lands, and waters, and
conducts supporting research
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Department of Agriculture: Conducts leasing programs (in
conjunction with DOI) for geothermal lands
Department of Defense: Controls use of some federal lands
and resources.
In the absence of broad coordination among these agencies,
controls-related environmental research can be inefficient, at best.
Sharing data on emission, environmental impacts, and the performance
of controls is essential to a coordinated controls development re-
search program. Any lesser linkage would invite delays in commer-
cialization and waste of federal resources. Specifically, the Panel
recommends:
Coordination among key agencies through the Panel mechanism
for a federal research strategy for environmental control
Increased coordination through the Panel mechanism with
industry and environmental groups on controls-related issues
Joint monitoring of production sites on a continuing basis
for the purpose of developing a better understanding of envi-
ronmental concerns and controls.
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