SRI/USEPA-GHG-VR-26B
September 2004
Environmental
Technology
Verification Report
UTC Fuel Cells PC25C Power Plant -
Gas Processing Unit Performance for
Anaerobic Digester Gas
Greenhouse Gas Technology Center
Southern Research Institute
Under a Cooperative Agreement With
U.S. Environmental Protection Agency
and
Under Agreement With
IW5EHDA New York State Energy Research and Development Authority
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EPA REVIEW NOTICE
This report has been peer and administratively reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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THE ENVIRONMENTAL TECHNOLOGY VERIFICATION PROGRAM
v-xEPA
Agei
ETV Joint Verification Statement
SOUTHERN RESEARCH
U.S. Environmental Protection Agency INSTITUTE
TECHNOLOGY TYPE: Carbon Based Digester or Sour Gas Processing
System
APPLICATION: Anaerobic Digester Gas
TECHNOLOGY NAME: Gas Processing Unit (GPU)
COMPANY: US Filter/Westates Carbon
ADDRESS: Lowell, Massachusetts
E-MAIL: mcdonoughli@,usfilter. com
The U.S. Environmental Protection Agency (EPA) has created the Environmental Technology
Verification (ETV) program to facilitate the deployment of innovative or improved environmental
technologies through performance verification and dissemination of information. The goal of the ETV
program is to further environmental protection by accelerating the acceptance and use of improved and
cost-effective technologies. ETV seeks to achieve this goal by providing high-quality, peer-reviewed data
on technology performance to those involved in the purchase, design, distribution, financing, permitting,
and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations, stakeholder groups that
consist of buyers, vendor organizations, and permitters, and with the full participation of individual
technology developers. The program evaluates the performance of technologies by developing test plans
that are responsive to the needs of stakeholders, conducting field or laboratory tests, collecting and
analyzing data, and preparing peer-reviewed reports. All evaluations are conducted in accordance with
rigorous quality assurance protocols to ensure that data of known and adequate quality are generated and
that the results are defensible.
The Greenhouse Gas Technology Center (GHG Center), one of six verification organizations under the
ETV program, is operated by Southern Research Institute in cooperation with EPA's National Risk
Management Research Laboratory. The GHG Center has collaborated with the New York State Energy
and Development Authority (NYSERDA) to evaluate the performance of several combined heat and
power (CHP) systems. One such technology is the PC25CC Fuel Cell Power Plant (PC25CC) offered by
United Technologies Corporation (UTC) Fuel Cells. The PC25C is a phosphoric acid fuel cell capable of
producing nominal 200 kW of electrical power with the potential to produce an additional 205 kW of
heat. The PC25C selected for this verification is fueled by anaerobic digester gas (ADG) produced at a
S-l
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water pollution control plant (WPCP). The PC25C tested includes a gas processing unit (GPU) that treats
the ADG prior to use as a fuel. Under a partnership between NYSERDA, New York Power Authority
(NYPA), and others, a total of eight fully interconnected PC25C systems are being installed at four
WPCPs in Brooklyn, New York. Each system will be fueled with ADG generated from anaerobic
digestion of sewage sludge, and each system will incorporate a dedicated GPU to process the gas. The
GPUs used by UTC Fuel Cells are manufactured by US Filter/Westates Carbon. This verification
statement provides the results of the GPU performance verification. A separate verification statement and
report was issued for the PC25C performance evaluation.
TECHNOLOGY DESCRIPTION
The PC25C fuel cell generates electricity through an electrochemical process in which the energy stored
in a fuel is converted into alternating current (AC) electricity. The unit has a rated generating capacity of
nominal 200 kW at 480 volts. Electrical efficiency of the PC25C averages 35 to 40 percent, but total
system efficiency can rise to over 80 percent if the waste heat is reused in a cogeneration system. A
detailed description of the PC25C fuel cell system and power module can be found in both the Test and
Quality Assurance Plan and the PC25C Verification Report. The following GPU description is based on
information provided by UTC Fuel Cells and US Filter/We states and does not represent verified
information
Prior to use as a fuel, the raw ADG is processed using an integrated GPU. The GPU is electrically
integrated with the PC25C such that the fuel cell provides power and startup and shutdown control to the
GPU. The GPU includes a variable speed gas blower that is used to pressurize low pressure ADG fuel
supply as needed to overcome the GPU pressure drop. PC25C fuel pressure sensors and electronics are
used to control GPU blower speed. The GPU is designed primarily to remove hydrogen sulfide (H2S)
from the ADG because its presence in concentrations greater than 6 ppm can be damaging to the PC25C.
The GPU can also remove other potentially harmful ADG components such as other sulfur species and
hydrocarbons.
The GPU consists of three major components including a coalescing filter, activated carbon beds, and the
blower. The coalescing filter removes water vapor and entrained particulates from the raw gas. The GPU
is equipped with liquid traps to remove condensed water from the fuel supply line. Collected and
condensed water is piped back into the waste water treatment system at the plant.
The dry ADG is then directed to two 1,200 Ib carbon beds in series to capture H2S and other harmful
contaminants. Each bed is designed to operate for approximately six months with ADG containing up to
200 ppm H2S. The system is configured with the capability to operate using a single bed when a bed
needs to be changed out. Periodic monitoring of the H2S levels in the raw and processed ADG is
conducted manually by system operators. Additionally, periodic sampling of the carbon beds is
conducted to evaluate the condition of the carbon.
VERIFICATION DESCRIPTION
Testing was conducted at the Red Hook WPCP - a 60-million gallon per day secondary wastewater
treatment facility in Brooklyn, New York. Two PC25C fuel cell systems were installed at the Red Hook
WPCP in May of 2003 to provide on-site generation of power and hot water.
The ADG is produced at the Red Hook facility using a series of anaerobic sludge digesters and is
typically composed of 60 to 65 percent methane with a lower heating value (LHV) of 550 to 650 Btu/cf
The system is designed to switch to natural gas fuel whenever ADG methane concentrations are less than
around 50 percent, or ADG pressure is below 3 inches water column. Gas production rates at the facility
S-2
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vary depending on daily plant wastewater flow rates and ambient temperatures. Peak production rates
during the summer months can approach 750 cubic feet per minute. Approximately 6,000 cubic feet per
hour of the ADG is needed to operate both PC25C's at this site at full power. During times when ADG
production rates at the plant exceed this level, the excess gas is combusted using an enclosed flare.
Testing was conducted on May 19 and 20, 2004. Testing was conducted to evaluate GPU performance by
comparing the composition and quality of raw ADG to that of processed ADG. The following gas
compositional and quality criteria were evaluated on six raw and six corresponding processed ADG
samples:
• Gas properties (gross and net heating value, density, and compressibility)
• Gas composition (N2, O2, CO2, and Ci through C6)
• Sulfur compounds
• Volatile Organic Compounds (VOCs) and total halides
• Moisture content
Corresponding ADG samples were collected on both the upstream and downstream sides of the GPU and
submitted for analysis. Results of the analyses were used to evaluate GPU removal efficiency for
moisture, H2S and sulfur compounds, VOCs, and halides. The results also allowed the center to evaluate
the effects on ADG composition and heating value.
The GPU performance verification testing was completed in conjunction with the CHP efficiency testing
that was conducted on the PC25C. The efficiency testing was performed at three different fuel cell power
output commands including full power (about 193 kW), 150 kW, and 100 kW.
Quality Assurance (QA) oversight of the verification testing was provided following specifications in the
ETV Quality Management Plan (QMP). The GHG Center's QA manager conducted an audit of data
quality on at least 10 percent of the data generated during this verification and a review of the report.
Data review and validation was conducted at three levels including the field team leader (for data
generated by subcontractors), the project manager, and the QA manager. Through these activities, the
QA manager has concluded that the data meet the data quality objectives that are specified in the Test and
Quality Assurance Plan.
VERIFICATION OF PERFORMANCE
ADG Composition and Heating Value (Table S-l)
• There was very little variation in the composition and physical properties of both the raw and processed
ADG samples. The raw ADG was almost entirely CH4 and CO2 (62.25 and 37.60 percent-dry basis,
respectively), with a small amount of N2 (0. 14 percent) and trace levels of H2S (93 ppm) and VOCs. The
data indicate that the GPU introduces a slight dilution of ADG with air (required for H2S removal), but
the basic gas composition is otherwise unchanged.
The slight dilution of the gas reduces the average CHt concentration by about 1.4 percent, and
subsequently, the fuel heating value is reduced by the same amount on a volumetric basis. The gas
compositional changes are consistent across the range of ADG flow rates measured during the three
different test conditions. The density and compressibility of the gas is virtually unchanged by processing.
S-3
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Table S-l. Composition and Properties of Raw and Processed ADG (dry basis)
Sample ID
Raw ADG 1
Processed ADG 1
Change (%)
Raw ADG 2
Processed ADG 2
Change (%)
Raw ADG 3
Processed ADG 3
Change (%)
Raw ADG 4
Processed ADG 4
Change (%)
Raw ADG 5
Processed ADG 5
Change (%)
Raw ADG 6
Processed ADG 6
Change (%)
Avg. Raw ADG
Avg. Processed ADG
Avg. Change (%)
Gas Composition (%)
CH4
62.39
61.66
-1.18
62.23
60.87
-2.23
62.18
61.55
-1.02
62.56
61.83
-1.18
62.14
61.20
-1.54
61.99
61.13
-1.41
62.24
61.37
-1.43
C02
37.45
37.27
-0.48
37.59
36.76
-2.26
37.67
37.17
-1.35
37.26
36.89
-1.00
37.73
37.17
-1.51
37.90
37.35
-1.47
37.60
37.10
-1.34
N2
0.15
0.88
82.95
0.15
1.89
92.06
0.15
1.04
85.58
0.17
1.04
83.65
0.12
1.31
90.84
0.11
1.23
91.06
0.14
1.23
87.69
Heat Content (Btu/scf)
HHV
622.6
615.3
-1.19
621.1
607.4
-2.26
620.5
614.2
-1.03
624.3
617.0
-1.18
620.1
610.7
-1.54
618.6
610.0
-1.41
621.2
612.4
-1.43
LHV
560.4
553.8
-1.19
559.0
546.7
-2.25
558.5
552.8
-1.03
561.9
555.3
-1.19
558.1
549.7
-1.53
556.8
549.1
-1.40
559.1
551.2
-1.43
Relative
Density
0.919
0.921
0.25
0.920
0.922
0.23
0.921
0.921
0.02
0.917
0.918
0.12
0.921
0.923
0.13
0.923
0.924
0.09
0.920
0.921
0.14
Compres-
sibility
0.9969
0.9969
0.00
0.9969
0.9970
0.01
0.9969
0.9969
0.01
0.9969
0.9969
0.00
0.9969
0.9969
0.01
0.9968
0.9969
0.01
0.9969
0.9969
0.01
Sulfur Compounds Removal Efficiency (Table S-2)
Table S-2. GPU Removal Efficiency for Sulfur Compounds
Sulfur Compounds Detected (concentrations in ppb)
Sample ID
Raw ADG 1
Processed ADG 1
Removal Efficiency (%)
Raw ADG 2
Processed ADG 2
Removal Efficiency (%)
Raw ADG 3
Processed ADG 3
Removal Efficiency (%)
Average Removal
Efficiency (%)
Hydrogen sulfide
83,000
<4.0
> 99.995
100,000
<4.0
> 99.996
96,500
<4.0
> 99.996
> 99.996
Carbon disulfide
1,200
38
96.8
1,400
35
97.5
800
38
95.3
96.5
S-4
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The only sulfur compounds detected in measurable quantities in the raw ADG samples were H2S and
carbon disulfide.
Concentrations of H2S ranged from 83 to 100 ppm. Based on processed ADG sample results below the
analytical detection limit of 4.0 ppb for H2S, the average removal efficiency is greater than 99.996
percent. GPU removal efficiency for carbon disulfide averaged 96.5 percent. Breakthrough of carbon
disulfide was limited to 37 ppb.
VOCs Removal Efficiency (Table S-3)
• A total of 22 VOCs were detected in each of the raw ADG samples. Of these, 12 were found in
concentrations of 50 ppb or greater, as summarized in Table S-3. Ten other VOCs were detected in
low or trace amounts in the raw ADG samples. None of the 10 trace compounds were detectable in
the processed ADG samples.
• Concentrations of toluene averaged approximately 2,200 ppb in the raw ADG and were higher than
the remaining VOCs combined. GPU removal efficiency for toluene averaged 99.90 percent.
Removal efficiencies for the nine remaining alkanes and alkenes detected in the raw ADG samples
were generally greater than 96 percent.
• GPU removal efficiencies for vinyl chloride and acetone averaged 17.5 and 59.6 percent,
respectively. Still, breakthrough of these two compounds was limited to 130 and 15 ppb,
respectively. Vinyl chloride and 1,2-dichloroethene were the only two halides detected in the raw
ADG samples. Total halide removal efficiency averaged 65 percent.
ADG Moisture Content
Raw and processed ADG temperatures were relatively low during the test periods ranging from 77 to 82
°F. Subsequently, moisture content ranged from 15.5 to 23.0 milligrams per liter (mg/1). As such,
removal of condensed water by the GPU was not required.
S-5
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Table S-3. GPU Removal Efficiency for Volatile Organic Compounds
Sample ID
Raw ADG 1
Processed ADG 1
Removal Efficiency (%)
Raw ADG 2
Processed ADG 2
Removal Efficiency (%)
Raw ADG 3
Processed ADG 3
Removal Efficiency (%)
Average Removal
Efficiency (%)
Primary Volatile Organic Compounds Detected (concentrations in ppb)
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Details on the verification test design, measurement test procedures, and Quality Assurance/Quality
Control (QA/QC) procedures can be found in the Test Plan titled Test and Quality Assurance Plan -
Electric Power and Heat Generation Using the UTC PC25C Fuel Cell Power Plant and Anaerobic
Digester Gas (SRI 2004). Detailed results of the verification are presented in the final report titled
Environmental Technology Verification Report for The UTC Fuel Cells PC25C Power Plant - Gas
Processing Unit Performance for Anaerobic Digester Gas (SRI 2004). Both can be downloaded from the
GHG Center's web-site (www.sri-rtp.com) or the ETV Program web-site (www.epa.gov/etv).
Signed by Lawrence W. Reiter, Ph.D. 9/15/04 Signed by Stephen D. Piccot 9/10/04
Lawrence W. Reiter, Ph.D. Stephen D. Piccot
Acting Director Director
National Risk Management Research Laboratory Greenhouse Gas Technology Center
Office of Research and Development Southern Research Institute
Notice: GHG Center verifications are based on an evaluation of technology performance under specific,
predetermined criteria and the appropriate quality assurance procedures. The EPA and Southern Research Institute
make no expressed or implied warranties as to the performance of the technology and do not certify that a
technology will always operate at the levels verified. The end user is solely responsible for complying with any and
all applicable Federal, State, and Local requirements. Mention of commercial product names does not imply
endorsement or recommendation.
EPA REVIEW NOTICE
This report has been peer and administratively reviewed by the U.S. Environmental Protection Agency, and
approved for publication. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
S-7
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SRI/USEPA-GHG-VR-26B
September 2004
Greenhouse Gas Technology Center \e
A U.S. EPA Sponsored Environmental Technology Verification ( f^/ ) Organization
Environmental Technology Verification Report
UTC Fuel Cells PC25CC Power Plant - Gas Processing Unit
Performance for Anaerobic Digester Gas
Prepared By:
Greenhouse Gas Technology Center
Southern Research Institute
PO Box 13825
Research Triangle Park, NC 27709 USA
Telephone: 919/806-3456
Under EPA Cooperative Agreement R 82947801
and NYSERDA Agreement 7009
U.S. Environmental Protection Agency
Office of Research and Development
National Risk Management Research Laboratory
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711 USA
EPA Project Officer: David A. Kirchgessner
NYSERDA Project Officer: Richard Drake
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TABLE OF CONTENTS
Page
LIST OF FIGURES iii
LIST OF TABLES iii
ACKNOWLEDGMENTS iv
ACRONYMS AND ABBREVIATIONS v
1.0 INTRODUCTION 1-1
1.1. BACKGROUND 1-1
1.2. GAS PROCESSING UNIT TECHNOLOGY DESCRIPTION 1-2
1.3. RED HOOK WPCP DESCRIPTION AND SYSTEM INTEGRATION 1-4
1.4. PERFORMANCE VERIFICATION OVERVIEW 1-5
1.4.1. Anaerobic Digester Gas Composition and Physical Properties 1-5
1.4.2. Anaerobic Digester Gas Sulfur and VOC Compounds 1-6
1.4.3. Anaerobic Digester Gas Temperature and Moisture Content 1-6
2.0 VERIFICATION RESULTS 2-1
2.1. ANAEROBIC DIGESTER GAS COMPOSITION AND PHYSICAL
PROPERTIES 2-1
2.2. ANAEROBIC DIGESTER GAS SULFUR COMPOUNDS AND VOCS 2-3
2.3. ANAEROBIC DIGESTER GAS MOISTURE CONTENT 2-5
3.0 DATA QUALITY ASSESSMENT 3-1
3.1. DATA QUALITY OBJECTIVES 3-1
3.2. ANAEROBIC DIGESTER GAS COMPOSITION AND HEATING VALUE 3-1
3.3. ANAEROBIC DIGESTER GAS SULFUR AND VOC CONTENT 3-2
3.4. ANAEROBIC DIGESTER GAS MOISTURE CONTENT 3-3
4.0 TECHNICAL AND PERFORMANCE DATA SUPPLIED BY US
FILTER/WESTATES CARBON 4-1
5.0 REFERENCES 5-1
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LIST OF FIGURES
Page
Figure 1-1 PC25C System Schematic 1-3
Figure 1-2 The US Filter/We states Carbon GPU at Red Hook WPCP 1-4
Figure 2-1 ADG Composition Before and After the GPU 2-2
LIST OF TABLES
Page
Table 2-1 Summary of ADG Sample Collection 2-1
Table 2-2 Composition and Properties of Raw and Processed ADG 2-2
Table 2-3 GPU Removal Efficiency for Sulfur Compounds 2-3
Table 2-4 GPU Removal Efficiency for Volatile Organic Compounds 2-4
Table 2-5 ADG Moisture Content 2-5
Table 3-1 Summary of ADG VOCs QA/QC Checks 3-2
Table 3-2 Summary of ADG Sulfur Compounds QA/QC Checks 3-3
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ACKNOWLEDGMENTS
The Greenhouse Gas Technology Center wishes to thank NYSERDA, especially Richard Drake and Mark
Torpey, for reviewing and providing input on the testing strategy and this Verification Report. Thanks
are also extended to the New York Power Authority (NYPA), especially Joe Maki, for their input
supporting the verification and their assistance with coordinating field activities. Finally, thanks go out to
New York City's Environmental Protection staff at the Red Hook Water Pollution Control Plant for
hosting the test.
in
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ADG
ADQ
ANSI
APPCD
ASME
ATL
Btu
Btu/scf
Cl
ccv
CH4
CHP
CO2
DC
DG
DOE
DQO
EPA
ETV
°F
ft3
GC
GHG Center
GPU
HHV
HRSG
H2S
ICAL
ISO
kW
Ib
LCS
LHV
MOD
mol
N2
NIST
NYPA
NYSERDA
02
ORD
PC25C
ACRONYMS AND ABBREVIATIONS
anaerobic digester gas
Audit of Data Quality
American National Standards Institute
Air Pollution Prevention and Control Division
American Society of Mechanical Engineers
Air Toxics, Ltd.
British thermal units
British thermal units per standard cubic feet
quantification of methane
continuing calibration verification
methane
combined heat and power
carbon dioxide
direct current electricity
distributed generation
U.S. Department of Energy
data quality objective
Environmental Protection Agency
Environmental Technology Verification
degrees Fahrenheit
cubic feet
gas chromatograph
Greenhouse Gas Technology Center
gas processing unit
higher heating value
heat recovery steam generator
hydrogen sulfide
initial calibration
International Standards Organization
kilowatts
pounds
laboratory control sample
lower heating value
million gallons per day
molecular
nitrogen
National Institute of Standards and Technology
New York Power Authority
New York State Energy Research and Development Authority
oxygen
Office of Research and Development
PC25C Fuel Cell Power Plant
(continued)
IV
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ACRONYMS/ABBREVIATIONS
(continued)
PEA
ppb
ppm
psia
psig
QA/QC
QMP
scf
scfh
scfm
Southern
TQAP
TSA
UTC
VOCs
Performance Evaluation Audit
parts per billion
parts per million
pounds per square inch, absolute
pounds per square inch, gauge
Quality Assurance/Quality Control
Quality Management Plan
standard cubic feet
standard cubic feet per hour
standard cubic feet per minute
Southern Research Institute
Test and Quality Assurance Plan
technical systems audit
United Technologies Corporation
volatile organic compounds
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1.0 INTRODUCTION
1.1. BACKGROUND
The U.S. Environmental Protection Agency's Office of Research and Development (EPA-ORD) operates
the Environmental Technology Verification (ETV) program to facilitate the deployment of innovative
technologies through performance verification and information dissemination. The goal of ETV is to
further environmental protection by accelerating the acceptance and use of improved and innovative
environmental technologies. Congress funds ETV in response to the belief that there are many viable
environmental technologies that are not being used for the lack of credible third-party performance data.
With performance data developed under this program, technology buyers, financiers, and permitters in the
United States and abroad will be better equipped to make informed decisions regarding environmental
technology purchase and use.
The Greenhouse Gas Technology Center (GHG Center) is one of six verification organizations operating
under the ETV program. The GHG Center is managed by EPA's partner verification organization,
Southern Research Institute (Southern), which conducts verification testing of promising greenhouse gas
mitigation and monitoring technologies. The GHG Center's verification process consists of developing
verification protocols, conducting field tests, collecting and interpreting field and other data, obtaining
independent peer-reviewed input, and reporting findings. Performance evaluations are conducted
according to externally reviewed verification Test and Quality Assurance Plans (TQAP) and established
protocols for quality assurance.
The GHG Center is guided by volunteer groups of stakeholders. These stakeholders guide the GHG
Center as to which technologies are most appropriate for testing, on how to help disseminate results, and
in reviewing Test Plans and Technology Verification Reports (Report). The GHG Center's Executive
Stakeholder Group consists of national and international experts in the areas of climate science and
environmental policy, technology, and regulation. It also includes industry trade organizations,
environmental technology finance groups, governmental organizations, and other interested groups. The
GHG Center's activities are also guided by industry specific stakeholders who provide guidance on the
verification testing strategy related to their area of expertise and peer-review key documents prepared by
the GHG Center.
A technology area of interest to some GHG Center stakeholders is distributed electrical power generation
(DG), particularly with combined heat and power (CHP) capability. DG refers to electricity generation
equipment, typically ranging in size from 5 to 1,000 kilowatts (kW), that provides electric power at a
customer's site. A DG unit can be connected directly to the customer or to a utility's transmission and
distribution (T&D) system. Examples of technologies available for DG include gas turbine generators,
internal combustion engine generators (gas, diesel, other), photovoltaics, wind turbines, fuel cells, and
microturbines. DG technologies provide customers one or more of the following main services: standby
generation (i.e., emergency backup power), peak shaving generation (during high-demand periods), base-
load generation (constant generation), and CHP generation. An added environmental benefit of some DG
technologies is the ability to fuel these systems with renewable energy sources such as anaerobic digester
gas (ADG) or landfill gas. These gases, when released to atmosphere, contribute millions of tons of
methane emissions annually in the U.S. Cost-effective technologies are available that can stem this
emission growth by recovering methane and using it as an energy source.
1-1
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The GHG Center and the New York State Energy Research and Development Authority (NYSERDA)
have agreed to collaborate and share the cost of verifying several new DG technologies located
throughout the State of New York. One such technology is the PC25C Fuel Cell Power Plant (PC25C)
offered by United Technologies Corporation (UTC) Fuel Cells. The PC25C is a phosphoric acid fuel cell
capable of producing nominal 200 kW of electrical power with the potential to produce an additional 205
kW of heat. The PC25C selected for this verification is fueled by ADG produced at a water pollution
control plant (WPCP). The PC25C verified here includes a gas processing unit (GPU) that treats the
ADG prior to use as a fuel. Under a partnership between NYSERDA, New York Power Authority
(NYPA), and others, a total of eight fully interconnected PC25C systems are being installed at four
WPCPs in Brooklyn, New York. Each system will be fueled with ADG generated from anaerobic
digestion of sewage sludge, and each system will incorporate a dedicated GPU to process the gas. The
GPUs used by UTC Fuel Cells are manufactured by US Filter/Westates Carbon. The PC25C and GPU
system selected for this verification is located at the Red Hook WPCP operated by the New York City
Department of Environmental Protection.
The GHG Center evaluated the performance of the PC25C and the unit's GPU at the Red Hook facility in
June 2004. This report presents the results of the GPU performance verification. Results of the PC25C
performance verification can be found in a separate verification statement and report titled Environmental
Technology Verification Report - Electric Power and Heat Generation Using the UTC PC25C Fuel Cell
Power Plant and Anaerobic Digester Gas [1]. It can be downloaded from the GHG Center's web-site
(www.sri-rtp.com) or the ETV Program web-site (www.epa.gov/etv).
Details on the verification test design, measurement test procedures, and Quality Assurance/Quality
Control (QA/QC) procedures can be found in the TQAP titled Test and Quality Assurance Plan- Electric
Power and Heat Generation Using the UTC PC25C Fuel Cell Power Plant and Anaerobic Digester Gas
[2]. It can also be downloaded from the web-sites noted above. The TQAP describes the rationale for the
experimental design, the testing and instrument calibration procedures planned for use, and specific
QA/QC goals and procedures. The TQAP was reviewed and revised based on comments received from
NYSERDA, NYPA, and the EPA Quality Assurance Team. The TQAP meets the requirements of the
GHG Center's Quality Management Plan (QMP) and satisfies the ETV QMP requirements.
The remainder of Section 1.0 describes the GPU system technology and test facility and outlines the
performance verification procedures that were followed. Section 2.0 presents test results, and Section 3.0
assesses the quality of the data obtained. Section 4.0, submitted by US Filter/Westates Carbon, presents
additional information regarding the CHP system. Information provided in Section 4.0 has not been
independently verified by the GHG Center.
1.2. GAS PROCESSING UNIT TECHNOLOGY DESCRIPTION
The PC25C fuel cell generates electricity through an electrochemical process in which the energy stored
in a fuel is converted into alternating current (AC) electricity. The unit has a rated generating capacity of
nominal 200 kW at 480 volts. Electrical efficiency of the PC25C averages 35 to 40 percent, but total
system efficiency can rise to over 80 percent if the waste heat is reused in a cogeneration system. Figure
1-1 provides a simple schematic of the PC25C system and its three major components and is followed by
a brief description of the GPU. A detailed description of the PC25C fuel cell system and power module
can be found in both the TQAP and the PC25C Verification Report.
1-2
-------
Gas Processing Unit
Natural Gas
Supply
Raw ADG
Supply
V
Condensate
480 volt
Service
GPU Control
Panel
Heat Recovery
*" Interface
Cooling Module
Figure 1-1. PC25C System Schematic
Prior to use as a fuel, the raw ADG is processed using an integrated GPU. The GPU used here is
manufactured by US Filter/Westates Carbon and is specifically designed for integration with the PC25C
(shown in Figure 1-2). The GPU is electrically integrated with the PC25C such that the fuel cell provides
power and startup or shutdown control to the GPU. The GPU includes a variable speed gas blower that is
used to pressurize low pressure ADG fuel supply as needed to overcome GPU pressure drop. PC25C fuel
pressure sensors and electronics are used to control GPU blower speed. The GPU is designed primarily to
remove hydrogen sulfide (H2S) from the ADG because its presence is damaging to the PC25C. The GPU
can also remove other potentially harmful ADG components such as other sulfur species and
hydrocarbons and has a drip leg to remove condensed water.
The GPU consists of three major components including a coalescing filter, activated carbon beds, and the
blower. The coalescing filter removes water vapor and entrained particulates from the raw gas. The GPU
is equipped with liquid traps to remove condensed water from the fuel supply line. Collected and
condensed water is piped back into the waste water treatment system at the plant.
The dry ADG is then directed to two 1,200 Ib carbon beds in series to capture H2S and other harmful
contaminants. Each bed is designed to operate for approximately six months with ADG containing up to
200 ppm H2S. The system is configured with the capability to operate using a single bed when a bed
needs to be changed out. Periodic monitoring of the H2S levels in the raw and processed ADG is
conducted manually by system operators. Additionally, periodic sampling of the carbon beds is
conducted to evaluate the condition of the carbon.
1-3
-------
Figure 1-2. The US Filter/Westate Carbon GPU at Red Hook WPCP
1.3. RED HOOK WPCP DESCRIPTION AND SYSTEM INTEGRATION
The Red Hook WPCP is a 60-million gallons per day (MGD) secondary wastewater treatment facility
located at 63 Flushing Avenue in Brooklyn, New York. Two PC25C fuel cell systems were installed at
the Red Hook WPCP in May of 2003 to provide on-site generation of power and hot water.
The Red Hook facility currently purchases power from the local utility [Consolidated Edison (ConEd)] to
meet its entire electrical demand. Facility heat demand for process heat, space heating, and hot water
production varies by season, but averages around 11.0 x 106 Btu/hr in winter months and 7.20 x 106 Btu/hr
in summer months. Heat demand is met under normal site operations using low-pressure steam supplied
by an adjacent cogeneration facility. The cogeneration facility (owned and operated by Cogeneration
Technologies, Inc.) is a 286 MW combined-cycle gas-fired turbine and steam turbine equipped with a
heat recovery steam generator (HRSG) capable of producing 800,000 Ib/hr steam. A small fraction of the
steam produced at the facility is directed to the Red Hook WPCP to meet the process heat, space heating,
and hot water production demands. Total annual steam flow to the Red Hook site has averaged
approximately 54.4 x 106 Ib/yr during the past three years, representing less than one percent of the
cogeneration facility's steam generation capacity.
1-4
-------
Each of the two fuel cells includes a dedicated GPU and is configured to use either natural gas or ADG
produced at the site as fuel. ADG is the primary fuel under normal site operations with natural gas used
only during fuel cell startup or as a backup fuel during digester upset conditions.
The ADG is produced at the Red Hook facility using a series of anaerobic sludge digesters and is
typically composed of 60 to 65 percent methane with a lower heating value (LHV) of 550 to 650 Btu/cf.
Preliminary ADG composition data collected at the site indicate that methane concentrations as low as 40
percent are rare, but possible. The system is designed to switch to natural gas fuel whenever methane
concentrations are less than around 50 percent or ADG pressure is less than 3 inches w.c. Gas production
rates at the facility will also vary depending on daily plant wastewater flow rates and ambient
temperatures. Peak production rates during the summer months can approach 750 cubic feet per minute.
Approximately 6,000 cfh of the ADG is needed to operate both PC25C's at full power. During times
when ADG production rates at the plant exceed this level, the excess gas is combusted using an enclosed
flare.
1.4. PERFORMANCE VERIFICATION OVERVIEW
Testing was conducted to evaluate GPU performance by comparing the composition and quality of raw
ADG to that of processed ADG. The following gas compositional and quality criteria were evaluated on
raw and processed ADG samples:
• Gas properties (gross and net heating value, density, and compressibility)
• Gas composition (N2, O2, CO2, and Ci through C6)
• Sulfur compounds
• Volatile organic compounds (VOCs) and total halides
• Moisture content
Corresponding ADG samples were collected on both the upstream and downstream sides of the GPU and
submitted for analysis. Results of the analyses were used to evaluate GPU removal efficiency for
moisture, H2S and sulfur compounds, VOCs, and halides. The results also allowed the center to evaluate
the effects of the GPU on ADG composition and heating value.
The GPU performance verification testing was completed in conjunction with the CHP efficiency testing
that was conducted on the PC25C. The efficiency testing was performed at three different fuel cell power
output commands including full power (about 193 kW), 150 kW, and 100 kW. Gas flow rate through the
GPU (and consumed by the PC25C) was measured during all test periods using a Dresser Roots Series
B3, Model 5M175 rotary meter and logged electronically as 1-minute averages.
Sections 1.3.1 through 1.3.3 briefly describe the verification ADG sampling and analytical procedures.
Detailed descriptions of the sample collection, handling, custody, and analytical procedures that were
followed during this verification can be found in the TQAP.
1.4.1. Anaerobic Digester Gas Composition and Physical Properties
During the PC25C efficiency tests, a total of six processed ADG samples were collected (two samples at
each of the three power commands). To evaluate GPU performance, six corresponding raw ADG
samples were collected during these tests. Samples were collected in 600 ml stainless steel canisters and
submitted to Empact Analytical Systems, Inc., of Brighton, CO for analysis. Compositional analysis was
conducted in accordance with ASTM Specification D1945 for quantification of methane (Cl) to hexane
1-5
-------
plus (C6+), nitrogen, oxygen, and carbon dioxide [3]. The compositional data were then used in
conjunction with ASTM Specification D3588 to calculate LHV, relative density, and compressibility of
the gas [4].
1.4.2. Anaerobic Digester Gas Sulfur and VOC Compounds
For evaluation of GPU sulfur and VOC removal performance, three sets of corresponding raw and
processed ADG samples were collected in 1-liter Tedlar bags (all on the second day of testing to
minimize sample holding times). These samples were submitted to Air Toxics, Ltd. of Folsom, California
(ATL) for VOC and sulfur compounds analysis. The VOC analyses were conducted in accordance with
EPA Method TO-15 [5], and the sulfur compounds analyses were conducted using ASTM Method 5504
[6]. Collected samples were protected from light and express shipped to the laboratory for next day
analysis. Method 5504 recommends that bag samples be analyzed for sulfur compounds within 24 hours
of collection. The actual holding time for samples collected here was approximately 32 hours because of
shipping time constraints.
A total of 63 VOCs are included in the analysis with individual compound reporting limits ranging from
6.2 to 25 ppb for the raw ADG samples and 1.4 to 5.6 ppb for the processed ADG samples (reporting
limits are defined as the value that can be accurately detected for any particular analyte on each
instrument). Results of the TO-15 analyses were used to compute halide concentrations. This is done by
summing the products of the concentration of each halide species detected and the number of halide
atoms per mole of each species (e.g., 10 ppbv of carbon tetrachloride will contribute 40 ppbv to the total
halide concentration reported).
A total of 20 sulfur compounds are included in the analysis with individual compound reporting limits of
800 ppb for raw ADG samples and 4.0 ppb for processed ADG.
1.4.3. Anaerobic Digester Gas Temperature and Moisture Content
GHG Center personnel determined ADG moisture content in the field using ASTM D4888-88 [7]. A
total of five corresponding moisture determinations were conducted on the raw and processed ADG at the
same sampling locations where canister and bag samples were collected. A Drager measurement system
including a hand pump and Drager detector tubes was used. The detector tubes provide moisture content
in units of milligrams per liter (mg/1) at the specified conditions.
A single ADG temperature sensor was located near the gas flow meter to continuously monitor ADG
temperature during the verification period. Temperatures were logged electronically as 1-minute
averages. To verify that these measurements are representative of the sampled ADG, three manual
temperature readings were taken at the raw ADG sampling port (outdoors) and compared to the
electronically logged gas temperature near the processed ADG sampling port (indoors). All readings
agreed within 1.2 °F, indicating that the logged processed ADG temperature data is representative of raw
ADG temperatures during the test periods.
1-6
-------
2.0
VERIFICATION RESULTS
The verification testing was conducted on May 19 and 20, 2004. ADG sampling was conducted in
conjunction with the PC25C efficiency verification testing. The GPU carbon beds had approximately
2,900 hours of operation prior to starting this testing, and were therefore well within the expected 6 month
carbon lifespan. The sampling matrix and basic ADG flow rate characteristics are summarized in Table
2-1.
Table 2-1. Summary of ADG Sample Collection
PC25C
Operating
Condition
Full load, or
193 kW
75 percent
load, or 152
kW
50 percent
load, or 102
kW
Average
ADG Flow
Rate (scfm)
53.02
40.32
27.80
Average
ADG
Temp. (°F)
81.5
80.4
77.5
77.4
77.4
77.4
77.1
Sample ID
Raw ADG Canister 1
Processed ADG Canister 1
Processed ADG Canister 2
Raw ADG Canister 2
Processed ADG Canister 3
Raw ADG Canister 3
Processed ADG Canister 4
Raw ADG Canister 4
Raw ADG Tedlar Bag 1
Processed ADG Tedlar Bag 1
Raw ADG Tedlar Bag 2
Processed ADG Tedlar Bag 2
Raw ADG Tedlar Bag 3
Processed ADG Tedlar Bag 3
Raw ADG Canister 5
Processed ADG Canister 5
Raw ADG Canister 6
Processed ADG Canister 6
Date (Time)
Collected
5/19/04 (0905)
5/19/04(0910)
5/19/04 (1300)
5/19/04(1315)
5/19/04 (1600)
5/19/04(1605)
5/20/04 (0900)
5/20/04(0910)
5/20/04 (0935)
5/20/04 (0940)
5/20/04(1055)
5/20/04(1100)
5/20/04(1155)
5/20/04(1200)
5/20/04(1230)
5/20/04 (1235)
5/20/04(1600)
5/20/04 (1605)
Collected samples were shipped to the appropriate laboratories along with proper chain of custody
documentation (Empact Analytical for canister samples and Air Toxics Ltd. for bag samples), and were
received in good condition. Results of ADG analyses were submitted to the GHG Center by the
laboratories along with proper QA/QC analytical documentation (described in Section 3.0). Sections 2.1
through 2.4 summarize the results of the testing. The laboratory reports detailing sample analyses are on
file at the GHG Center and available on request, but too voluminous for inclusion here.
2.1. ANAEROBIC DIGESTER GAS COMPOSITION AND PHYSICAL PROPERTIES
There was very little variation in the composition and physical properties of both the raw and processed
ADG samples. Figure 2-1 shows the average ADG composition on a dry basis before and after GPU
processing.
2-1
-------
0.12%N,
37.6 % CO,
1.2%N, 0.3 %09
62.3%CH4 37.1%C02 ^ 61.4 %CH,
Raw ADG Processed ADG
Figure 2-1. ADG Composition Before and After GPU (dry basis)
The raw ADG was almost entirely Clr^ and CO2, with a small amount of N2, and trace levels of H2S and
VOCs (see Section 2.2). The data indicate that the GPU introduces a slight dilution of ADG with air
(which is required for H2S removal), but the basic gas composition is otherwise unchanged.
Table 2-2 summarizes the composition of each raw and processed ADG sample. The summary includes
the LHV, HHV, relative density, and compressibility of the raw and processed gas samples that were
calculated based on the compositional analyses. The change in each of the gas properties is shown, along
with the average change.
Table 2-2. Composition and Properties of Raw and Processed ADG (dry basis)
Sample ID
Raw ADG 1
Processed ADG 1
Change (%)
Raw ADG 2
Processed ADG 2
Change (%)
Raw ADG 3
Processed ADG 3
Change (%)
Raw ADG 4
Processed ADG 4
Change (%)
Raw ADG 5
Processed ADG 5
Change (%)
Raw ADG 6
Processed ADG 6
Change (%)
Avg. Raw ADG
Avg. Processed ADG
Avg. Change (%)
Gas Composition (%)
CH4
62.39
61.66
-1.18
62.23
60.87
-2.23
62.18
61.55
-1.02
62.56
61.83
-1.18
62.14
61.20
-1.54
61.99
61.13
-1.41
62.24
61.37
-1.43
C02
37.45
37.27
-0.48
37.59
36.76
-2.26
37.67
37.17
-1.35
37.26
36.89
-1.00
37.73
37.17
-1.51
37.90
37.35
-1.47
37.60
37.10
-1.34
N2
0.15
0.88
82.95
0.15
1.89
92.06
0.15
1.04
85.58
0.17
1.04
83.65
0.12
1.31
90.84
0.11
1.23
91.06
0.14
1.23
87.69
Heat Content (Btu/scf)
HHV
622.6
615.3
-1.19
621.1
607.4
-2.26
620.5
614.2
-1.03
624.3
617.0
-1.18
620.1
610.7
-1.54
618.6
610.0
-1.41
621.2
612.4
-1.43
LHV
560.4
553.8
-1.19
559.0
546.7
-2.25
558.5
552.8
-1.03
561.9
555.3
-1.19
558.1
549.7
-1.53
556.8
549.1
-1.40
559.1
551.2
-1.43
Relative
Density
0.919
0.921
0.25
0.920
0.922
0.23
0.921
0.921
0.02
0.917
0.918
0.12
0.921
0.923
0.13
0.923
0.924
0.09
0.920
0.921
0.14
Compres-
sibility
0.9969
0.9969
0.00
0.9969
0.9970
0.01
0.9969
0.9969
0.01
0.9969
0.9969
0.00
0.9969
0.9969
0.01
0.9968
0.9969
0.01
0.9969
0.9969
0.01
2-2
-------
Figure 2-1 and Table 2-2 show that the slight dilution of the gas reduces the average CFLt concentration
by about 1.4 percent, and subsequently the fuel heating value is reduced by the same amount. The gas
compositional changes are fairly uniform across the range of ADG flow rates measured during the three
different test conditions. The density and compressibility of the gas is virtually unchanged by processing.
2.2. ANAEROBIC DIGESTER GAS SULFUR COMPOUNDS AND VOCs
All Tedlar bag samples for sulfur and VOCs analyses were received by the laboratory in good condition,
and analyzed within 32 hours of collection. The only sulfur compounds detected in measurable quantities
in the raw ADG samples were H2S and carbon disulfide. Table 2-3 summarizes the concentrations of
each compound before and after processing by the GPU, and the GPU removal efficiency for each.
Table 2-3. GPU Removal Efficiency for Sulfur Compounds
Sample ID
Raw ADG 1
Processed ADG 1
Removal Efficiency (%)
Raw ADG 2
Processed ADG 2
Removal Efficiency (%)
Raw ADG 3
Processed ADG 3
Removal Efficiency (%)
Average Removal
Efficiency (%)
Sulfur Compounds Detected (concentrations in ppb)
Hydrogen sulfide
83,000
<4.0
> 99.995
100,000
<4.0
> 99.996
96,500
<4.0
> 99.996
> 99.996
Carbon disulfide
1,200
38
96.8
1,400
35
97.5
800
38
95.3
96.5
Concentrations of H2S in the raw ADG ranged from 83 to 100 ppm. All processed ADG sample
concentrations were below the analytical detection limit of 4.0 ppb for H2S. Therefore, the average
removal efficiency is greater than 99.996 percent. GPU removal efficiency for carbon disulfide averaged
96.5 percent. Breakthrough of carbon disulfide was limited to 37 ppb.
A total of 22 VOCs included in the TO-15 analysis were detected in each of the raw ADG samples. Of
these, 12 were found in concentrations of 50 ppb or greater. These 12 predominant VOCs are
summarized in Table 2-4 along with the concentrations of each in the processed gas samples and the GPU
removal efficiency for each. Ten other VOCs were detected in low or trace amounts in the raw ADG
samples. None of the 10 trace compounds were detectable in the processed ADG samples.
2-3
-------
Table 2-4. GPU Removal Efficiency for Volatile Organic Compounds
Sample ID
Raw ADG 1
Processed ADG 1
Removal Efficiency (%)
Raw ADG 2
Processed ADG 2
Removal Efficiency (%)
Raw ADG 3
Processed ADG 3
Removal Efficiency (%)
Average Removal
Efficiency (%)
Primary Volatile Organic Compounds Detected (concentrations in ppb)
a
•a
•e
o
CJ
160
125
21.9
140
130
7.1
170
130
23.5
17.5
=
o
Ot
tj
25
17
32.0
40
17
57.5
120
13
89.2
59.6
a
a
o>
1
0
fS O
*? 2
fl •••
'3 O
100
<1.4
>98.6
110
<1.8
>98.4
120
<1.4
>98.8
>98.6
a
a
O)
N
g
46
<1.4
>97.0
52
< 1.8
>96.5
51
<1.4
>97.3
>96.9
O)
03
"5.
W
65
<1.4
>97.8
69
<1.8
>97.4
72
<1.4
>98.1
>97.8
=
o>
=
0
H
1,700
2.0
99.9
2,500
2.3
99.9
2,500
2.1
99.9
99.9
O)
=
o>
N
=
O>
W
80
<1.4
>98.3
93
<1.8
>98.1
100
<1.4
>98.6
>98.3
O)
=
1
&
a"
44
<1.4
>96.8
49
<1.8
>96.3
54
<1.4
>97.4
>96.9
o
=
o
=
o
c.
PM
40
<1.4
>96.5
55
<1.8
>96.7
56
<1.4
>97.5
>96.9
o
=
o
_S
"o
X
210
<1.4
>99.3
285
< 1.8
>99.4
310
<1.4
>99.5
>99.4
O)
=
o
1
•A a
n "C
-T H
61
<1.4
>97.7
96
<1.8
>98.1
100
<1.4
>98.6
>98.1
O)
=
o
1
4l
98.3
160
<1.8
>98.9
180
<1.4
>99.2
>98.8
2-4
-------
Raw ADG concentrations of toluene averaged approximately 2,200 ppb and were higher than the
remaining VOCs combined. GPU removal efficiency for toluene averaged 99.90 percent. Average
removal efficiencies for the nine remaining alkanes and alkenes were greater than 96 percent.
GPU removal efficiencies for vinyl chloride and acetone were much lower, averaging only 17.5 and 59.6
percent, respectively. Still, breakthrough of these two compounds was limited to 130 and 17 ppb,
respectively. Vinyl chloride and cis 1,2-dichloroethene were the only two halides detected in the raw
ADG samples. Total halides concentrations averaged 377 and 131 ppb for the raw and processed ADG
samples. Total halide removal efficiency averaged 65 percent.
2.3. ANAEROBIC DIGESTER GAS MOISTURE CONTENT
Table 2-5 summarizes the raw and processed ADG moisture content during the verification period. As
noted earlier, gas temperatures measured at the ADG gas meter were determined to be representative of
both raw and processed ADG temperatures at the sampling locations. Table 2-5 shows that ADG
temperatures were also consistent throughout the testing ranging from 77.3 to 81.6 °F. The GPU is
designed to remove only condensed water through the drip leg and water vapor in the ADG can actually
enhance performance. At these temperatures, there was no condensed water in the ADG and therefore,
essentially no GPU moisture removal was required or achieved.
Table 2-5. ADG Moisture Content (mg/1)
Sample ID
Runl
Run 2
Run 3
Run 4
Run5
Average
Gas Temp.
(°F)
81.6
81.6
80.4
77.7
77.3
79.7
Raw ADG
(mg/1)
15.5
16.0
15.0
18.0
23.0
17.5
Processed
ADG (mg/1)
15.5
16.0
14.0
18.0
20.0
16.7
2-5
-------
3.0 DATA QUALITY ASSESSMENT
3.1. DATA QUALITY OBJECTIVES
The GHG Center selects methodologies and instruments for all verifications to ensure that the desired
level of data quality in the final results is obtained. The GHG Center specifies DQOs for each
verification parameter before testing starts and uses these goals as a statement of data quality. Ideally,
quantitative DQOs are established based on the level of confidence in results needed by stakeholders or
potential users of a technology. In some cases, such as this verification, quantitative DQOs are not well
defined and therefore, qualitative DQOs are established.
During this verification, determination of each of the primary verification parameters was conducted
based on published reference methods. The qualitative DQOs for this verification, then, are to meet all of
the QA/QC requirements of each method. In some cases, the laboratory conducting the analyses has
internal QA/QC checks that are performed in addition to the method requirements. The analytical
methods used here were introduced in Section 1.3. Additional details regarding these methods can be
found in the TQAP. A summary of the QA/QC requirements and results for each method are provided in
the following sections.
This verification was supported by an Audit of Data Quality (ADQ) conducted by the GHG Center QA
Manager. During the ADQ, the QA Manager randomly selected data supporting each of the primary
verification parameters and followed the data through the analysis and data processing system. The ADQ
confirmed that no systematic errors were introduced during data handling and processing.
A performance evaluation audit (PEA) was planned but not conducted. The planned PEA consisted of a
blind audit of the analytical laboratory conducting the gas compositional analyses. Similar PEAs were
submitted to Empact on two similar verifications within the past year to evaluate analytical accuracy on
the methane analyses [8, 9]. These audits qualified as PEAs as required by the ETV QMP. Both audits
indicated analytical accuracy within 0.5 percent, and repeatability of within ± 0.2 percent. Since the same
sampling and analytical procedures were used here by the same laboratory analyst, the audit was not
repeated a third time. This deviation from the TQAP was approved by the QA and Project Managers.
3.2. ANAEROBIC DIGESTER GAS COMPOSITION AND HEATING VALUE
For all ADG samples collected (Table 2-1), sample collection date, time, run number, and canister
identification number were logged and laboratory chain of custody forms were completed and shipped
with the samples. Copies of the chain of custody forms and results of the analyses are stored in the GHG
Center project files. Collected samples were shipped to Empact for compositional analysis and
determination of LHV per ASTM Methods D1945 and D3588. Empact maintains strict continuous
calibration criteria on the instrumentation used for the compositional analyses using certified reference
standards. Copies of these calibration data are stored in the GHG Center project files.
Duplicate analyses were conducted on three of the raw ADG samples and three of the processed ADG
samples collected during the controlled test periods. Duplicate analysis is defined as the analysis
performed by the same operating procedure and using the same instrument for a given sample volume.
Results of the duplicate analyses showed an average analytical repeatability of 0.33 percent for both
methane and LHV.
3-1
-------
3.3. ANAEROBIC DIGESTER GAS SULFUR AND VOC CONTENT
ADG sample collection date, time, run number, and canister ID were logged and laboratory chain of
custody forms were completed and shipped with the samples. Copies of the chain of custody forms and
results of the analyses are stored in the GHG Center project files. Collected samples were shipped to Air
Toxics for analysis. Like Empact, Air Toxics maintains strict continuous calibration criteria on the
instrumentation used for these analyses using certified reference standards. The GHG Center has copies
of these procedures on file. Other QA/QC criteria required by the methods and used by Air Toxics are
summarized in Tables 3-2 and 3-3, along with the results achieved for these samples.
Table 3-1. Summary of ADG VOCs QA/QC Checks
QC Check
Five point
instrument
calibration
(ICAL)
Laboratory
control sample
(LCS)
Continuing
calibration
verification
(CCV)
Laboratory blank
Surrogates
Duplicate
analyses
Minimum
Frequency
Prior to sample
analysis
After each ICAL
Prior to sample
analysis
After the CCV
As each
standard, blank,
and sample is
analyzed
10% of the
samples
Acceptance Criteria
Relative standard deviation < 30%
90 percent of the compounds
quantified must be within 70 to
130% of expected values
90 percent of the compounds
quantified must be within 70 to
130% of expected values
Results lower than reporting limit
70 to 130% surrogate recovery
required
Relative percent difference of <
25% for compounds detected 5
times higher than reporting limits
Results Achieved
Results acceptable
All compounds within
the range of 74 to 143%
of expected values3
All compounds within
the range of 78 to 122%
of expected values
All compounds below
reporting limit
Recoveries ranged from
94 to 105% for all
samples
Relative difference <
25% for compounds
detected
Two compounds exceeded the LCS criteria, both of which were not detected in samples collected
here.
The GHG Center obtained, reviewed, and archived documentation from Air Toxics that each of these QC
checks were conducted and criteria were achieved. A detailed description of these QA/QC checks is
provided in the TQAP.
3-2
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Table 3-2. Summary of ADG Sulfur Compounds QA/QC Checks
QC Check
Five point
instrument
calibration
(ICAL)
Laboratory
control sample
(LCS)
Laboratory blank
Duplicate
analyses
Minimum
Frequency
Prior to sample
analysis
After each ICAL
After the ICAL
10% of the
samples
Acceptance Criteria
Relative standard deviation < 30%
90 percent of the compounds
quantified must be within 70 to
130% of expected values
Results lower than reporting limit
Relative percent difference of <
25% for compounds detected 5
times higher than reporting limits
Results Achieved
Results acceptable
All compounds within
the range of 72 to 107%
of expected values
All compounds below
reporting limit
Relative difference <
25% for compounds
detected
3.4. ANAEROBIC DIGESTER GAS MOISTURE CONTENT
The DQO for ADG moisture determinations using the Drager chips will be evaluated by analyzing
replicate samples. One back-to-back moisture sample was collected during the verification period as a
check for the method's repeatability. The back-to-back sample was collected immediately after the
preceding moisture sample, and both results were 16.0 mg/1. Using published gas saturation tables, the
Center also determined that at the ADG temperatures measured, saturated gas would have moisture
content of approximately 22 mg/1 which is consistent with the data generated here using the detector
tubes. It should be noted that only five moisture samples were collected at each sampling location instead
of the planned six.
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4.0 TECHNICAL AND PERFORMANCE DATA SUPPLIED BY US FILTER/WESTATES
CARBON
Note: This section provides an opportunity for UTC Fuel Cells and US Filter/We states Carbon to
provide additional comments concerning the GPU System and its features not addressed elsewhere in the
Report. The GHG Center has not independently verified the statement made in this section.
4-1
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UTC Fuel Cells
PC25 C INSTALLATION MANUAL
A Umlctl TachnglogiO* Company
Main Menu
Install Home
Effective Date: 03/10/03
Page H-2
H.I.3. Gas Processing Unit (GPU)
The Gas Processing Unit (GPU) filters and pressurizes the ADG prior to entering the modified PC-25C Fuel
Cell. The GPU uses two treated activated carbon beds to remove hydrogen sulfide from die ADG stream,
T!ie unit is sized to process up to 4800 standard cubic feet per hour of ADG with an average H?S concentration
of 200 ppm. The following table presents the ADG fuel inlet limits that were die design basis for the Gas
Processing Unit (GPU). These limits represent the raw ADG Gas supply from the silo thai a Fuel Cell Installa-
tion can use.
Table H.2. PC-25 GPU Inlet Condition Limits
Item
Major Fuel Constituent (%Wet)
CH4
coz
H,0
N2
O2
Temperature (°F)
Pressure (hvg) *
Boosted
Non Boosted
Contaminants
H?S (ppmv)
Organic Sulfur (ppmv)
Halides (ppmv)
Ammonia (ppmv)
Oleflns (%)
Liquid Water (pphj
Flow Rate (SCFM)
Nominal
Case
60.8
31.1
5.5
2.5
0.1
95
8
60
200
1
0
0
0
1
60
Individual
Minimum
50
0
0.7
0
0
55
3
60
0
0
0
0
0
0
Individual
Maximum
100
45
5.5
2.5
0.3
100
20
80
1500
1
2
0.5
0,5
2
86
* Dependent on Blower Option
In addition to the 3" Inlet and outlet gas lines, there are 0.5" condensaie drain lines, which are required to
be connected to a sanitary drain. The location and size of the GPU mechanical interfaces are located in
UTCFC Drawing FC19520. The GPU stands eight foot high, and has an 8' x 10' foot print. When siting, the
GPU. be sure to maintain a 10' clearance between these units and any electrical/sparking devices. The GPU
and (he optional Gas Analysis Unit can be within 10' of each other.
Unpublished Work. Copyright 2003. UTC Fuel Cells
FCR-13258C
4-2
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5.0 REFERENCES
[1] Southern Research Institute, Environmental Technology Verification Report Report - Electric
Power and Heat Generation Using the UTC PC25C Fuel Cell Power Plant and Anaerobic
Digester Gas, SRI/USEPA-GHG-VR-26, www.sri-rtp.com. Greenhouse Gas Technology Center,
Southern Research Institute, Research Triangle Park, NC. September 2004.
[2] Southern Research Institute, Test and Quality Assurance Plan - Electric Power and Heat
Generation Using the UTC PC25C Fuel Cell Power Plant and Anaerobic Digester Gas,
SRI/USEPA-GHG-QAP-26, www.sri-rtp.com. Greenhouse Gas Technology Center, Southern
Research Institute, Research Triangle Park, NC. January 2004.
[3] American Society for Testing and Materials, Standard Test Method for Analysis of Natural Gas
by Gas Chromatography, ASTM D1945-98, West Conshohocken, PA. 2001.
[4] American Society for Testing and Materials, Standard Practice for Calculating Heat Value,
Compressibility factor, and Relative Density of Gaseous Fuels, ASTM D3588-98. West
Conshohocken, PA. 2001.
[5] USEPA, Compendium of Methods for the Determination of Toxic Organic Compounds in
Ambient Air, Compendium Method TO-15 - Determination of Volatile Organic Compounds
(VOCs) In Air Collected in Specially Prepared Canister and Analyzed by Gas
Chromatography/Mass Spectrometry (GC/MS). Center for Environmental Research Information,
ORD, EPA. January 1997.
[6] American Society for Testing and Materials, Standard Practice for Determination of Sulfur
Compounds In Natural Gas by Gas Chromatography and Chemiluminescense, ASTM D5 5 04-01.
West Conshohocken, PA. 2001.
[7] American Society for Testing and Materials, Standard Practice for Determination of Moisture
Content in Natural Gas by Stain Tube Detector, ASTM D4888-88. West Conshohocken, PA,
2001.
[8] Southern Research Institute, Environmental Technology Verification Report: Combined Heat
and Power at a Commercial Supermarket - Capstone 60 kW Microturbine CHP System,
SRI/USEPA-GHG-QAP-27, www.sri-rtp.com. Greenhouse Gas Technology Center, Southern
Research Institute, Research Triangle Park, NC. September 2003.
[9] Southern Research Institute, Environmental Technology Verification Report: Residential Electric
Power Generation Using the Plug Power SU1 Fuel Cell System, SRI/USEPA-GHG-QAP-25,
www.sri-rtp.com. Greenhouse Gas Technology Center, Southern Research Institute, Research
Triangle Park, NC. September 2003.
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