SRI/USEPA-GHG-VR-26
September 2004
Environmental
Technology
Verification Report
Electric Power and Heat Generation Using
UTC Fuel Cells' PC25C Power Plant and
Anaerobic Digester Gas
Prepared by:
Greenhouse Gas Technology Center
Southern Research Institute
Under a Cooperative Agreement With
U.S. Environmental Protection Agency
and
IWSERDA Under Agreement With
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
SERft
U.S. Environmental Protection Agency
IVYSERDA
SOUTHERN RESEARCH
INSTITUTE
ETV Joint Verification Statement
TECHNOLOGY TYPE:
APPLICATION:
TECHNOLOGY NAME:
COMPANY:
ADDRESS:
WEB ADDRESS:
Phosphoric Acid Fuel Cell Combined With Heat
Recovery System
Distributed Electrical Power and Heat Generation
Using UTC Fuel Cells' PC25C Power Plant and
Anaerobic Digester Gas
PC25C Fuel Cell Power Plant - Model C
UTC Fuel Cells, LLC
195 Governors Highway
South Windsor, Connecticut 06074
www.utcfuelcells.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.
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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. A technology of interest to GHG Center stakeholders is the use of
fuel cells as distributed generation (DG) sources. DG refers to power-generation equipment that provides
electric power at a site much closer to customers than central station 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, if released to atmosphere, contribute
millions of tons of methane emissions annually in the U.S. Cost-effective technologies are available that
can significantly reduce these emissions by recovering methane and using it as an energy source.
Recently, ADG production from waste management facilities has become a promising alternative for
fueling DG technologies. The recovered methane can fuel power generators to produce electricity, heat,
and hot water. The improved efficiency of combined heat and power DG systems and the ability to use
renewable fuels make them a viable alternative to traditional power generation technologies.
The GHG Center collaborated with the New York State Energy Research and Development Authority
(NYSERDA) to evaluate the performance of the PC25C Model C Fuel Cell Power Plant (PC25C) offered
by United Technologies Corporation Fuel Cells (UTC). 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 owned and operated by the New York Power Authority
(NYPA). It is located at the Red Hook Water Pollution Control Plant (WPCP) operated by the New York
City Department of Environmental Protection. The system is fueled by ADG produced at the Red Hook
facility.
TECHNOLOGY DESCRIPTION
The following technology description is based on information provided by UTC and NYPA and does not
represent verified information. The PC25C is a phosphoric acid fuel cell (PAFC) that 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. System specifications state that electrical efficiency of the PC25C averages 35 to 40 percent, but
total system efficiency can rise to about 80 percent if the waste heat is reused in a cogeneration system.
The PC25C system consists of three major components including: (1) the gas processing unit (GPU), (2)
the power module, and (3) the cooling module.
Prior to use as a fuel, the raw ADG is processed using an integrated GPU. The GPU is manufactured by
US Filter and specifically designed for integration with the PC25C. The GPU is designed primarily to
remove hydrogen sulfide (H2S) from the ADG, as its presence is damaging to the PC25C. The GPU will
also remove other potentially harmful ADG components such as other sulfur species and volatile organic
compounds. A separate verification statement and report titled Environmental Technology Verification
Report - UTC PC25C Fuel Cell Power Plant - Gas Processing Unit Performance for Anaerobic Digester
Gas provides results of GPU performance testing.
The PC25C Power Module consists of three components including: (1) the fuel processor, (2) the fuel
cell stack, and (3) the power conditioner. The PC25C uses catalytic steam reforming (CSR) to produce a
reformed fuel (reformate) rich in H2 from the ADG. According to UTC, the CSR reforming process
yields higher H2 per unit of fuel compared to other reforming processes, boosting fuel quality and fuel cell
efficiency. The fuel cell stack uses a phosphoric acid electrolyte to generate direct current (DC) power
from reformate. After the fuel cell stack, the spent reformed fuel sent to the CSR burner to provide heat
for the endothermic reforming process. The reformer exhaust is combined in the condenser along with
the spent air from the fuel cell stack. There, water is recovered and sent back to the cooling water loop,
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and uncondensed water vapor is exhausted to the atmosphere. A power conditioner converts the DC
power to AC using an inverter.
Two PC25C systems are installed at the Red Hook plant, providing a potential 400 kW of power to offset
power purchased from the utility grid. The PC25C systems will also offset a portion of the heat provided
to Red Hook by a large neighboring cogeneration facility. Both fuel cells are 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.
When the fuel cells are not in service or excess ADG is produced, it is combusted in an enclosed flare.
VERIFICATION DESCRIPTION
Testing was conducted from May 19 through June 19, 2004. The verification included a series of
controlled test periods in which the GHG Center intentionally modulated the unit to produce electricity at
nominal power output commands of 200, 150, and 100 kW. Three replicate test runs were conducted at
each point. The controlled test periods were followed by 30 days of continuous monitoring to verify
electric power production, heat recovery, and power quality performance over an extended period. The
classes of verification parameters evaluated were:
• Heat and Power Production Performance
• Emissions Performance (NOX, CO, THC, CH4, and CO2)
• Power Quality Performance
Evaluation of heat and power production performance included verification of power output, heat
production, electrical efficiency, thermal efficiency, and total system efficiency. Electrical efficiency was
determined according to the ASME Performance Test Code for Fuel Cells (ASME PTC-50). Tests
consisted of direct measurements of fuel flow rate, fuel lower heating value (LHV), and power output.
Heat recovery rate and thermal efficiency were determined according to ANSI/ASHRAE test methods
and consisted of direct measurement of heat-transfer fluid flow rate and differential temperatures.
Ambient temperature, barometric pressure, and relative humidity measurements were also collected to
characterize the condition of the combustion air used by the fuel cell. All measurements were recorded as
one-minute averages.
The evaluation of emissions performance occurred simultaneously with efficiency testing. Pollutant
concentration and emission rate measurements for nitrogen oxides (NOX), carbon monoxide (CO), total
hydrocarbons (THC), methane (CH^), and carbon dioxide (CO2) were conducted in the PC25C exhaust
stack. All test procedures used in the verification were U.S. EPA reference methods recorded in the Code
of Federal Regulations (CFR). Pollutant emissions are reported as concentrations in parts per million by
volume, dry (ppmv) corrected to 15-percent oxygen (O2), and as mass per unit time (Ib/hr). The mass
emission rates are also normalized to power output and reported as pounds per megawatt hour (Ib/MWh).
Annual NOX and CO2 emissions reductions resulting from the use of the PC25C were estimated by
comparing measured emission rates with corresponding emission rates for the baseline scenario for the
Red Hook plant. The baseline scenario consists of emissions associated with generation of an amount of
power by utilities equivalent to that produced by the fuel cell (based on average regional grid emission
factors for New York State) plus estimated emissions from combustion of an amount of ADG using the
flare equivalent to that consumed by the fuel cell.
Electrical power quality parameters, including electrical frequency and voltage output, were measured
during the controlled and 30-day extended tests. Current and voltage total harmonic distortions (THD)
and power factors were also monitored to characterize the quality of electricity supplied to the end user.
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The guidelines listed in "The Institute of Electrical and Electronics Engineers' (IEEE) Recommended
Practices and Requirements for Harmonic Control in Electrical Power Systems" were used to perform
power quality testing.
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 this 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 quality objectives specified in the Test and Quality Assurance
Plan were met with the exception of the efficiency determinations. Due to a conservative uncertainty
estimate in the heat input determination, the efficiency DQOs were slightly exceeded.
VERIFICATION OF PERFORMANCE
Heat and Power Production Performance
PC25C HEAT AND POWER PRODUCTION
Test Condition
(Power
Command)
200 kW
150 kW
100 kW
Electrical Power Generation
Power
Delivered
(kW)
193.1
152.3
101.5
Efficiency
(%)
36.8
38.2
37.4
Heat Production Performance
Heat
Production
(103Btu/hr)
1,018
700
478
Potential
Thermal Efficiency
(%)
56.9
51.5
51.7
Potential
CHP System
Efficiency
(%)
93.8
89.8
89.0
Electrical efficiency averaged approximately 37.5 percent over the range of PC25C operation.
The Red Hook WPCP does not have demand for the heat generated by the PC25C. All heat produced by
the fuel cell is removed through the unit's cooling module loop. The heat production rates summarized
in the table represent the total heat removed at the cooling module. Based on these heat removal rates,
potential thermal efficiency at full load was 56.9 percent and potential combined heat and power system
efficiency averaged 93.8 percent.
During the 30-day monitoring period, the PC25C operated on ADG for a total of 165 hours. During this
time, a total of 27,748 kWhr electricity was generated at an average rate of 166 kW, and 120.4 million
Btu (35,296 kWh) of heat was removed through the cooling module at an average heat recovery rate of
730 MBtu/hr. Numerous power upsets at the Red Hook facility during the verification period reduced
the amount of PC25C run time during the verification period. Testing conducted by the GHG Center on
a different PC25C showed an availability of 97 percent.
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Emissions Performance
PC25C EMISSIONS (Ib/MWh)
Power
Command
200 kW
150 kW
lOOkW
NOX
0.013
0.013
0.013
CO
0.029
0.051
0.078
THC
0.78
1.36
1.37
CH4
0.80
1.40
1.19
CO2
1,437
1,314
1,451
• NOX emissions were consistent at all three loads tested and averaged 0.013 Ib/MWh. CO emissions
averaged 0.029 Ib/MWh at full load and increased slightly as power output was reduced.
• THC emissions ranged from 0.78 Ib/MWh at full load to 1.37 Ib/MWh at the 100 kW power demand.
The PC25C ventilation system draws ambient air through the exhaust duct and also into the fuel cell
stack. Background hydrocarbons in the room air were measured and used to correct the measured
exhaust stack emissions. Even after this correction for background hydrocarbons, reported THC
levels are much higher than has been reported for three other PC25C tests. Further information is
available in the Verification Report.
• Compared to the baseline emissions scenario (regional grid emission factors plus flare emissions),
annual NOX emission reductions are estimated to be 0.45 tons when operating the PC25C for an
average 165 hours per month (as observed during the verification period). At an estimated PC25C
availability rate of 97 percent (based on previous testing by the GHG Center), estimated annual NOX
emission reductions increase to 1.82 tons. For CO2, estimated annual emission reductions at the
operating conditions observed during the period are 337 tons. At the expected 97 percent availability,
annual CO2 emission reductions increase to an estimated 1,346 tons.
Power Quality Performance
• Average electrical frequency was 60.00 Hz and average voltage output was 487.6 volts.
• During the first half of the verification period, power factor remained relatively constant at 99.9 percent.
However, power factor reversed to approximately -87 percent following a long period of downtime. The
cause of this reversal is not clear.
• The average current THD was 12.5 percent and the average voltage THD was 2.3 percent. Current THD
exceeded the IEEE recommended threshold of 5 percent on several occasions.
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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 Production Using the UTC Fuel Cells PC25C 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 Electric Power and Heat Production Using the UTC Fuel Cells PC25C Power Plant
and 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. 9/22/04 Signed by Stephen D. Piccot 9/13/04
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.
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SRI/USEPA-GHG-VR-26
September 2004
Greenhouse Gas Technology Center
A U.S. EPA Sponsored Environmental Technology Verification ( YF/ ) Organization
Environmental Technology Verification Report
Electric Power and Heat Generation Using the UTC Fuel Cells'
PC25C Power Plant and 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. PC25C FUEL CELL TECHNOLOGY DESCRIPTION 1-2
1.3. RED HOOK WPCP FACILITY AND SYSTEM INTEGRATION 1-4
1.4. PERFORMANCE VERIFICATION OVERVIEW 1-6
1.4.1. Heat and Power Production Performance 1-7
1.4.2. Measurement Equipment 1-8
1.4.3. Power Quality Performance 1-10
1.4.4. Emissions Performance 1-11
1.4.5. Estimated Annual Emission Reductions 1-12
2.0 VERIFICATION RESULTS 2-1
2.1. OVERVIEW 2-1
2.2. HEAT AND POWER PRODUCTION PERFORMANCE 2-2
2.2.1. Electrical Power Output, Heat Production, and Efficiency During
Controlled Tests 2-2
2.2.2. Electrical and Thermal Energy Production and Efficiency During the
Extended Test Period 2-6
2.3. POWER QUALITY PERFORMANCE 2-8
2.4. EMISSIONS PERFORMANCE 2-10
2.4.1. PC25C Exhaust Emissions 2-10
2.4.2. Estimation of Annual NOX and CO2 Emission Reductions 2-12
3.0 DATA QUALITY ASSESSMENT 3-1
3.1. DATA QUALITY OBJECTIVES 3-1
3.2. RECONCILIATION OF DQOs AND DQIs 3-2
3.2.1. Power Output 3-5
3.2.2. Electrical Efficiency 3-6
3.2.2.1. PTC-50 Requirements for Electrical Efficiency Determination 3-7
3.2.2.2. Ambient Measurements 3-7
3.2.2.3. Fuel Flow Rate 3-8
3.2.2.4. Fuel Lower Heating Value 3-8
3.2.3. Heat Production and Thermal Efficiency 3-8
3.2.4. Total Efficiency 3-9
3.2.5. Exhaust Stack Emission Measurements 3-9
3.2.5.1. NOX, CO, THC, CO2, and O2 Concentrations 3-10
3.2.5.2. CH4 Concentrations 3-11
3.2.5.3. Exhaust Gas Volumetric Flow Rate 3-11
4.0 TECHNICAL AND PERFORMANCE DATA SUPPLIED BY UTC FUEL CELLS 4-1
5.0 REFERENCES 5-1
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Figure 1-1
Figure 1-2
Figure 1-3
Figure 2-1
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 2-6
LIST OF FIGURES
Page
PC25C System Schematic 1-3
PC25C Integration Schematic for Red Hook WPCP 1-5
Schematic of Measurement System 1-9
Power and Heat Production During the Controlled Test Periods 2-3
Power and Heat Production During the Extended Monitoring Period 2-7
PC25C Efficiency During the Extended Monitoring Period 2-7
PC25 C Voltage and Frequency During Extended Monitoring Period 2-8
PC25C Power Factor During Extended Monitoring Period 2-8
PC25 C Current and Voltage THD During Extended Monitoring Period 2-9
Table 1-1
Table 1-2
Table 2-1
Table 2-2
Table 2-3
Table 2-4
Table 2-5
Table 2-6
Table 3-1
Table 3-2
Table 3-3
Table 3-4
Table 3-6
LIST OF TABLES
Page
Controlled and Extended Test Periods 1-7
Summary of Emissions Testing Methods 1-12
PC25C Heat and Power Production Performance 2-4
PC25C Heat Recovery Unit and Cooling Module Operating Conditions 2-5
PC25C Heat Input Determinations 2-6
Summary of PC25C Power Quality 2-9
PC25C Emissions During Controlled Periods 2-11
Estimated Annual PC25C Emission Reductions 2-13
Verification Parameter Data Quality Objectives 3-1
Summary of Data Quality Goals and Results 3-3
Results of Additional QA/QC Checks 3-6
Variability Observed in Operating Conditions 3-7
Summary of Emissions Testing QA/QC Checks 3-10
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ACKNOWLEDGMENTS
The Greenhouse Gas Technology Center wishes to thank NYSERDA, especially Richard Drake and Mark
Torpey, for supporting this verification and 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 his input supporting the verification and his 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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ACRONYMS AND ABBREVIATIONS
AC
ADQ
Amp
ANSI
ASHRAE
ASME
Btu
Btu/hr
Btu/min
Btu/scf
CAR
CSR
CH4
CHP
CO
CO2
CT
DAS
DG
DOE
DQI
DQO
dscf/106Btu
EPA
ETV
FID
GC
GHG Center
GPM
hr
Hz
IEEE
ISO
kW
kWh
Ib
Ib/dscf
Ib/hr
Ib/kWh
Ib/MWh
LHV
103Btu/hr
MW
MWh
106Btu/hr
alternating current
Audit of Data Quality
amperes
American National Standards Institute
American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
American Society of Mechanical Engineers
British thermal units
British thermal units per hour
British thermal units per minute
British thermal units per standard cubic feet
Corrective Action Report
catalytic steam reforming
methane
combined heat and power
carbon monoxide
carbon dioxide
current transformer
data acquisition system
distributed generation
U.S. Department of Energy
data quality indicator
data quality objective
dry standard cubic feet per million British thermal units
Environmental Protection Agency
Environmental Technology Verification
flame ionization detector
gas chromatograph
Greenhouse Gas Technology Center
gallons per minute
hour
hertz
Institute of Electrical and Electronics Engineers
International Standards Organization
kilowatts
kilowatt hours
pounds
pounds per dry standard cubic foot
pounds per hour
pounds per kilowatt-hour
pounds per megawatt-hour
lower heating value
thousand British thermal units per hour
megawatt
megawatt-hour
million British thermal units per hour
(continued)
IV
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ACRONYMS/ABBREVIATIONS
(continued)
NDIR
NIST
NOX
NSPS
NYPA
NYSERDA
O2
PEA
ppmv
ppm
psia
psig
QA/QC
QMP
RH
rms
RTD
scf
scfh
scfm
Southern
TQAP
THCs
THD
ton/yr
TSA
VAC
VAR
nondispersive infrared
National Institute of Standards and Technology
nitrogen oxides
New Source Performance Standards
New York Power Authority
New York State Energy Research and Development Authority
oxygen
Performance Evaluation Audit
parts per million volume
parts per million volume, dry
pounds per square inch, absolute
pounds per square inch, gauge
Quality Assurance/Quality Control
Quality Management Plan
relative humidity
root mean square
resistance temperature detector
standard cubic feet
standard cubic feet per hour
standard cubic feet per minute
Southern Research Institute
Test and Quality Assurance Plan
total hydrocarbons
total harmonic distortion
tons per year
technical systems audit
volts alternating current
volt-ampere reactive
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1.0 INTRODUCTION
1.1. BACKGROUND
The U.S. Environmental Protection Agency's Office of Research and Development 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 and established protocols
for quality assurance.
The GHG Center is guided by volunteer groups of stakeholders, who direct the GHG Center regarding
which technologies are most appropriate for testing, help disseminate results, and review test plans and
technology verification reports. 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 under 1,000 kilowatts (kW), that
provides electric power at a customer's site (as opposed to central station generation). A DG unit can be
connected directly to the customer or to a utility's transmission and distribution 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 significantly reduce these emissions by recovering
methane and using it as an energy source.
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 Fuel Cells (UTC). 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 owned and operated by the New York Power
Authority (NYPA) and 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
1-1
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partnership between NYSERDA, NYPA, and others, a total of eight fully interconnected PC25C systems
will be installed at four WPCPs in Brooklyn, New York. Each system will be fueled with ADG generated
from anaerobic digestion of sewage sludge. The PC25C 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 CHP system by conducting field tests over a
30-day verification period (May 19 - June 19, 2004). These tests were planned and executed by the GHG
Center to independently verify the electricity generation rate, thermal energy recovery rate, electrical
power quality, energy efficiency, emissions, and greenhouse gas emission reductions for the fuel cell
operating at the Red Hook WPCP. Details on the verification test design, measurement test procedures,
and Quality Assurance/Quality Control (QA/QC) procedures can be found in the document titled Test and
Quality Assurance Plan - 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). This Test and Quality Assurance Plan
(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 NYSRDA, 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 PC25C CHP 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 UTC Fuel Cells, presents
additional information regarding the CHP system. Information provided in Section 4.0 has not been
independently verified by the GHG Center.
1.2. PC25C FUEL CELL 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. According to UTC, electrical efficiency of the PC25C averages 35 to 40
percent, but total system efficiency can rise to about 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 including: (1) the GPU, (2) the power module, (3) the cooling module.
Gas Processing Unit
Prior to use as a fuel, the raw ADG is processed using an integrated GPU. The GPU used here is
manufactured by US Filter/We states and specifically designed for integration with the PC25C. The GPU
is electrically integrated with the PC25C such that the fuel cell provides power and startup/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, as its presence is damaging to the PC25C. The GPU will also remove other
potentially harmful ADG components such as other sulfur species and volatile organic compounds.
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 a drip leg 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.
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Gas Processing Unit
Raw AD'
Supply
Processed ADG
Dilution Air.
480 volt
Service
I
I
Exhaust to
Atmosphere
PC25
Exhaust
Natural Gas
Condensate
GPU Control
Panel
Power and
Control
Power Module
Power and
Control
Air
Heat Recovery
Interface
Cooling Module
Figure 1-1. PC25C System Schematic
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.
Power Module
The PC25C Power Module consists of three components including: (1) the fuel reformer, (2) the fuel cell
stack, and (3) the power conditioner. A reformed fuel (reformate) rich in H2 is derived from the
processed ADG in the reformer via catalytic steam reforming (CSR). According to UTC, the CSR
reforming process yields higher H2 per unit of fuel compared to other reforming processes, boosting fuel
quality and fuel cell efficiency. This occurs because all of the O2 needed to oxidize the carbon
compounds is provided by steam, which also contributes to the H2 content of the reformate. The
reformed fuel is then directed to the fuel cell stack.
The fuel cell stack uses an electrolyte [phosphoric acid (H3PO4)] which can approach concentrations of
100 percent. The electrodes are made of carbon paper coated with a finely dispersed platinum catalyst.
The catalyst strips electrons off the hydrogen-rich fuel at the anode. Positively charged hydrogen ions
then migrate through the electrolyte from the anode to the cathode. Electrons generated at the anode
cannot pass through this electrolyte and they travel through an external circuit, providing DC power, and
return to the cathode. The electrons, hydrogen ions, and oxygen form water, which is discharged from the
cell. The platinum catalyst at the electrodes speeds the reactions. Individual fuel cells can be combined
into a fuel cell "stack". The number of fuel cells in the stack determines the total voltage output. This set
of reactions in the fuel cell produces electricity and by-product heat. The reactions are:
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Anode Reaction: 2 H2 => 4 FT + 4 e-
Cathode Reaction: O2(g) + 4 H+ + 4 e- => 2 H2O
Overall Cell Reaction: 2 H2 + O2 => 2 H2O
The cell uses air directly as an oxidizing agent and can operate with impure hydrogen produced by
reforming other fuels. The CO2 formed as a byproduct of the reform process passes through the cell
without affecting its performance. After the fuel cell stack, the spent reformed fuel is sent to the CSR
burner to provide heat for the endothermic reforming process. The reformer exhaust is combined in the
condenser along with the spent air from the fuel cell stack. There, water is recovered and sent back to the
cooling water loop, and uncondensed water vapor is exhausted to the atmosphere. An induced draft fan
draws a constant stream of dilution air through the exhaust system to maintain proper draft on the power
module. In the power conditioner, the DC electricity produced by the fuel cell stack is converted to AC
power using an inverter.
Cooling Module
The cooling module is a cooling loop that is isolated from the heat recovery system. The cooling module
is used to remove unused heat generated by the Power Module and to maintain optimum internal
operating temperatures. A variable speed circulation pump controls the flow of fluid through the cooling
module loop in response to several temperature sensors within the PC25C. When heat recovery rates are
low, additional cooling is provided by the cooling module. Heat is removed through a radiator type air
heat exchanger.
1.3. RED HOOK WPCP FACILITY AND SYSTEM INTEGRATION
The Red Hook WPCP is a 60-million gallons per day 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. One of the PC25C
systems (ID No. 9274) was selected for this verification test.
The Red Hook facility purchases power from the local utility (Consolidated Edison) to meet its electrical
demand. Facility heat demand for process heat, space heating, and hot water production varies by season,
but averages around 11.0 x 106Btu/hr in winter months and 7.20 x 106Btu/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 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
million pounds per year during the past three years, representing less than one percent of the cogeneration
facility's steam generation capacity.
The Red Hook WPCP also has three gas- or oil-fired boilers that can meet plant heat demand should the
cogeneration facility not provide steam to the site. The boilers are identical York-Shipley Series 576
Steam Pak Boilers. Each 350 horsepower unit has a rated heat input of 14.7 x 106Btu/hr and a heat output
rate of 11.7 x 106Btu/hr. Steam output is rated at 12,075 Ib/hr. The boilers are rarely needed at the
facility because steam availability from the cogeneration facility is greater than 98 percent.
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Figure 1-2 provides a simplified schematic of fuel cell integration at the Red Hook site. The two PC25C
systems can provide a total of 400 kW of power to offset power purchased from ConEd. The PC25C
systems can also offset a small portion of the heat provided by the cogeneration facility (approximately
1.6 106Btu/hr, or about 14 percent of the average cold weather demand). Both fuel cells are 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. The ADG is
typically composed of 60 to 65 percent methane with a lower heating value (LHV) of 550 to 650 Btu/scf.
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 50 percent, or ADG pressure is less than 3 inches water column. 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 45,000 cubic feet per hour (cfh). All ADG is
combusted in a single enclosed flare when the fuel cells are not in use. The flare is a Whessoe-Varic
Model WV 249-15-4-24-6 ADG ground flare which was installed in 1988. Approximately 6,500 cfh of
the ADG is diverted from the flare and used as fuel with the two PC25C fuel cells in operation. Site
operators report that ADG production rates at the plant normally exceed the 6,500 cfh needed to operate
both fuel cells at full load at all times of normal site operations. ADG produced in excess of 6,500 cfh is
combusted in the flare.
•Power From
Utility Grid
Utility
Natural Gas
Supply
Low Pressure Steam
From Co-generation
Facility
Facility Hot Water
Header
Hot Water
Supply
Figure 1-2. PC25C Integration Schematic for Red Hook WPCP
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1.4. PERFORMANCE VERIFICATION OVERVIEW
This verification test was designed to evaluate the performance of the PC25C CHP system—not the
overall system integration or specific management strategy. The TQAP specified a series of controlled
test periods in which the unit was intentionally modulated to produce electricity at nominal power output
commands of 200, 150, and 100 kW. Additionally, the TQAP specified that these tests would be
conducted with the facility configured to maximize PC25C heat recovery potential. However, current
Red Hook WPCP standard operating procedures do not allow the site to be isolated from the neighboring
cogeneration facility. This plant configuration essentially eliminates all demand for heat from the
PC25Cs. Therefore, all heat currently produced by the PC25Cs is removed through the cooling modules.
For this test, heat recovery rates measured during the controlled test periods actually represent the total
heat produced and removed by the PC25C.
The controlled test periods were followed by a 30-day period of extended monitoring to evaluate power
and heat production and power quality over a range of ambient conditions and plant operations. During
this period, off-site PC25C operators maintained system operations. More details regarding the system
operations during this period are provided in Section 2.0. The specific verification parameters associated
with the test are listed below. Brief discussions of each verification parameter and its method of
determination are presented in Sections 1.4.1 through 1.4.5. Detailed descriptions of testing and analysis
methods are provided in the TQAP and not repeated here.
Heat and Power Production Performance
• Electrical power output and heat recovery rate at selected loads
• Electrical, thermal, and total system efficiency at selected loads
Power Quality Performance
• Electrical frequency
• Voltage output
• Power factor
• Voltage and current total harmonic distortion
Emissions Performance
• Nitrogen oxides (NOX), carbon monoxide (CO), total hydrocarbons (THC),
carbon dioxide (CO2), and methane (CH^ concentrations at selected loads
• NOX, CO, THC, CO2, and CH4 emission rates at selected loads
• Estimated NOX and greenhouse gas emission reductions
Each of the verification parameters listed were evaluated during the controlled or extended monitoring
periods as summarized in Table 1-1. This table also specifies the dates and time periods during which the
testing was conducted. Simultaneous monitoring for power output, heat recovery rate, heat input, ambient
meteorological conditions, and exhaust emissions was performed during each of the controlled test
periods. ADG samples were collected to determine fuel lower heating value and other gas properties.
Average electrical power output, heat recovery rate, energy conversion efficiency (electrical, thermal, and
total), and exhaust stack emission rates are reported for each test period.
Results from the extended test are used to report total electrical energy generated and used on site, total
thermal energy produced, greenhouse gas emission reductions, and electrical power quality. Greenhouse
gas emission reductions for on-site electrical power generation are estimated using measured greenhouse
gas emission rates and emissions estimates for electricity produced at central station power plants.
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Table 1-1. Controlled and Extended Test Periods
Controlled Test Periods
Start Date,
Time
05/19/04, 09:00
05/19/04, 15:50
05/20/04, 12:25
End Date,
Time
05/19/04, 14:25
05/20/04,11:20
05/20/04, 16:45
Test Condition
Power command of 200 kW, three 60-minute test runs
Power command of 150 kW, three 60-minute test runs
Power command of 100 kW, three 60-minute test runs
Verification Parameters
Evaluated
NOX, CO, CH4, CO2 emissions, and
electrical, thermal, and total
efficiency
Extended Test Period
Start Date,
Time
05/20/04, 17:00
End Date,
Time
06/19/04,11:48
Test Condition
PC25C operated as dispatched by
off-site UTC operators
Verification Parameters Evaluated
Total electricity generated; total heat
removed; power quality; and emission offsets
1.4.1. Heat and Power Production Performance
Electrical efficiency determination was based upon guidelines in the ASME Performance Test Code for
Fuel Cell Power Systems, PTC-50 [2], and was calculated using the average measured net power output,
fuel flow rate, and fuel lower heating value (LHV) during each controlled test period. The GPU and
cooling module are both powered by the fuel cell, creating internal parasitic loads. Two additional
parasitic loads that are external (not powered directly by the fuel cell) are the fuel cell stack ventilation
fan and the water circulation pump. These two small loads are less than 1 kW combined. This
verification did not include a separate measurement of these parasitic loads, and therefore reports the net
system efficiency (based on the usable power delivered by the system).
The electrical power output was measured continuously throughout the verification period using
instrumentation provided and installed by the GHG Center. Heat input was determined by metering the
fuel consumption and determining ADG energy content. Fuel gas sampling and energy content analysis
(via gas chromatograph) was conducted according to ASTM procedures to determine the lower heating
value of the ADG. Ambient temperature, relative humidity, and barometric pressure were measured near
the PC25C air intake to support the determination of electrical conversion efficiency as required in PTC-
50. Electricity conversion efficiency was computed by dividing the average electrical energy output by
the average energy input using Equation 1.
77=-
34U.\4kW
HI
(Equation 1)
where:
*7 = efficiency
kW = average net electrical power output measured over the test interval (kW),
(PC25C power delivered to site)
HI = average heat input using LHV over the test interval (Btu/hr); determined by
multiplying the average mass flow rate of ADG to the system converted to standard
cubic feet per hour (scfh) times the gas LHV (Btu per standard cubic foot, Btu/scf)
3412.14 = converts kWto Btu/hr
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Simultaneous with electrical power measurements, heat recovery and removal rate was measured using a
pair of heat meters. Separate meters were installed on both the hot water supply loop and the cooling
module loop. The meters enabled 1-minute averages of differential heat exchanger temperatures and
water flow rates to be monitored. Published fluid density and specific heat values for water were used so
that heat recovery rates for each meter could be calculated at actual conditions per ANSI/ASHRAE
Standard 125 [3].
Heat Recovery Rate (Btu/min) = VpCp (T1-T2) (Equation 2)
where:
V = total volume of liquid passing through the heat meter flow sensor during a minute (ft3)
p = density of water (lb/ft3), evaluated at the avg. temp. (T2 plus Tl)/2
Cp = specific heat of water (Btu/lb °F), evaluated at the avg. temp. (T2 plus Tl)/2
Tl = temperature of water exiting heat exchanger (°F), (see Figure 1-3)
T2 = temperature of water entering heat exchanger (°F), (see Figure 1-3)
The average heat recovery and removal rates measured during the controlled tests and the extended
monitoring period (total of the hot water loop and cooling module loop combined) represent the heat
production potential of the CHP system. Thermal energy conversion efficiency was computed as the
average heat recovered or removed divided by the average energy input:
r|T = 60 • Qavg / HI (Equation 3)
where:
r|T = thermal efficiency
Qavg = average heat recovered (Btu/min)
HI = average heat input using LHV (Btu/hr); determined by multiplying the average mass
flow rate of ADG to the system (converted to scfh) times the gas LHV (Btu/scf)
1.4.2. Measurement Equipment
Figure 1-3 illustrates the location of measurement variables contained in Equations 1 through 3. Power
output was measured using a 7500 ION Power Meter (Power Measurements Ltd.) at a rate of
approximately one reading every 8 to 12 milliseconds and logged on the Center's data acquisition system
(DAS) as 1-minute averages. The logged one-minute average kW readings were averaged over the
duration of each controlled test period to compute electrical efficiency. The kW readings were integrated
for the extended test period over the duration of the verification period to calculate total electrical energy
generated in units of kilowatt hours (kWh).
ADG fuel input was measured with an in-line Dresser-Roots Series B Model 5M175 rotary displacement
meter. The meter was equipped with a frequency transmitter manufactured by Love Controls (Model SC
478). This transmitter was mounted on the meter's index and provided a scaled 4-20 mA signal to the
DAS. The DAS recorded actual gas flow as one-minute averages. Gas temperature and pressure sensors
were installed to enable flow rate compensation to provide mass flow output at standard conditions.
A total of six ADG samples were collected and analyzed during the controlled test periods to determine
gas composition and heating value. Samples were collected at a point in the ADG delivery line
downstream of the meter and are representative of the PC25C fuel. All samples were submitted to
Empact Analytical Systems, Inc., of Brighton, CO, for compositional analysis in accordance with ASTM
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Specification D1945 for quantification of methane to hexane, nitrogen, oxygen, and carbon dioxide [4].
The compositional data were then used in conjunction with ASTM Specification D3588 to calculate LHV
and the relative density of the gas [5].
Raw ADG
PC25 System
Verification Boundary
Exhaust Gas
To Atmosphere
Power Module
AC Power
Waste Heat
Condensate to
Treatment Plant
Makeup
Water Supply
Hot Water Loop
Figure 1-3. Schematic of Measurement System
A total of six corresponding raw ADG samples were also collected to evaluate GPU performance. The
approach, procedures, and results of the GPU performance verification are reported in a separate
verification statement and report titled Environmental Technology Verification Report - UTC PC25C
Fuel Cell Power Plant- Gas Processing Unit Performance for Anaerobic Digester Gas [6].
Two Controlotron Model 1010EP1 energy meters were used to monitor the two hot water loops. These
meters are digitally integrated systems that include a portable computer, ultrasonic fluid flow transmitters,
and 1,000-ohm platinum resistance temperature detectors (RTDs). The meters have an overall rated
accuracy of ± 2 percent of reading and provide a continuous 4-20 mA output signal over a range of 0 to
200 gallons per minute (GPM). The water flow rate and supply and return temperature data used to
determine heat recovery rates were logged as one-minute averages throughout all test periods. The heat
transfer fluid density and specific heat were determined by using ASHRAE and ASME density and
specific heat values for water corrected to the average water temperature measured by the RTDs.
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1.4.3. Power Quality Performance
The GHG Center and its stakeholders developed an approach to evaluate power quality based on the
power quality parameters of interest and the measurement methods used in existing protocols and
standards [7, 8, 9]. The GHG Center measured and recorded the following power quality parameters
during the extended monitoring period:
• Electrical frequency
• Voltage
• Voltage THD
• Current THD
• Power factor
The 7500 ION power meter used for power output determinations was used to perform these
measurements as described below and detailed in the TQAP. The ION power meter continuously
measured electrical frequency at the generator's distribution panel. The DAS was used to record one-
minute averages throughout the extended period. The mean, maximum, and minimum frequencies as
well as the standard deviation are reported.
The PC25C generates power at nominal 480 volts (AC). The electric power industry accepts that voltage
output can vary within ±10 percent of the standard voltage without causing significant disturbances to the
operation of most end-use equipment. Deviations from this range are often used to quantify voltage sags
and surges. The ION power meter continuously measured true root mean square (rms) line-to-line
voltage at the generator's distribution panel for each phase pair. The DAS recorded one-minute averages
for each phase pair throughout the extended period as well as the average of the three phases. The mean,
maximum, and minimum voltages, as well as the standard deviation for the average of the three phases
are reported.
THD is created by the operation of non-linear loads. Harmonic distortion can damage or disrupt many
kinds of industrial and commercial equipment. Voltage harmonic distortion is any deviation from the
pure AC voltage sine waveform. THD gives a useful summary view of the generator's overall voltage
quality. The specified value for THD is a maximum of 5.0 percent based on "recommended practices for
individual customers" in the IEEE 519 Standard. The ION meter continuously measured voltage THD up
to the 63rd harmonic for each phase. The DAS recorded one-minute voltage THD averages for each phase
throughout the test period and reported the mean, minimum, maximum, and standard deviation for the
average THD for the three phases.
Current THD is any distortion of the pure current AC sine waveform. The current THD limits
recommended in the IEEE 519 standard range from 5.0 to 20.0 percent, depending on the size of the CHP
generator, the test facility's demand, and its distribution network design as compared to the capacity of
the local utility grid. Detailed analysis of the facility's distribution network and the local grid are beyond
the scope of this verification. The GHG Center, therefore, reports current THD data without reference to
a particular recommended THD limit. The ION power meter, as with voltage THD, continuously
measured current THD for each phase and reported the average, minimum, and maximum values for the
period.
The ION power meter also continuously measured average power factor across each generator phase.
The DAS recorded one-minute averages for each phase during all test periods. The GHG Center reported
the maximum, minimum, mean, and standard deviation power factors averaged over all three phases.
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1.4.4. Emissions Performance
Pollutant concentration and emission rate measurements for NOX, CO, THC, CH4, and CO2 were
conducted on the PC25C exhaust stack during all of the controlled test periods. Emissions testing
coincided with the efficiency determinations described earlier. Test procedures used were U.S. EPA
reference methods, which are well documented in the Code of Federal Regulations (CFR). The reference
methods include measurement system performance specifications and test procedures, quality control
procedures, and emission calculations (40CFR60, Appendix A) [10]. Table 1-2 summarizes the standard
test methods that were followed. The testing procedures and sampling system were specifically designed
for the extremely low pollutant concentrations expected. A detailed description of the methodology and
sampling system used is included in the TQAP and not repeated here. A complete discussion of the data
quality requirements is also presented in the TQAP.
The emissions testing was conducted by TRC Corporation of Windsor, Connecticut under the on-site
supervision of the GHG Center field team leader. The PC25C exhaust system includes separate exhaust
ducts from the reformer and fuel cell stack that are combined prior to discharge to atmosphere. The first
test run was conducted in the reformer exhaust stack where the majority of pollutants were expected.
After Run 1 however, a new sampling location was selected such that it included exhaust gases from the
reformer and fuel cell stack exhaust ducts, as well as the dilution air drawn through the PC25C exhaust
system to ventilate the unit (via an induced draft fan). This location was most representative of the actual
PC25C emissions to atmosphere. Sampling was conducted during each test for approximately 60 minutes
at a single point near the center of the combined PC25C exhaust stack.
Results of the gaseous pollutant testing are reported in units of parts per million volume dry (ppm) and
ppm corrected to 15-percent O2. Exhaust gas flow rate determinations were conducted during each test
run in accordance with EPA Method 2 to convert measured pollutant concentrations to mass emissions.
Stack gas velocity and temperature traverses were conducted using a calibrated thermocouple, a standard
pitot tube, and an inclined oil manometer. The number and location of traverse points sampled was
selected in accordance with EPA Method 1. Emission rates for each pollutant are then normalized to
system power output and reported in terms of Ib/kWh.
Table 1-2. Summary of Emissions Testing Methods
Pollutant
NOX
CO
THC
CH4
CO2
O2
EPA Reference
Method
7E
10
25A
18
3A
3A
Analyzer Type
Thermo-Electron Corporation (TECO) Model
42CH (chemiluminescense)
TECOI Model 48 (NDIR)
California Analytical Model 300 (FID)
Hewlett-Packard 5890 GC/FID
Servomex (NDIR)
Servomex (paramagnetic)
Range
0 - 2.5 ppm
0-10 ppm
0 - 100 ppm
0 - 100 ppm
0-20 %
0-25 %
At the conclusion of Run 2, it was apparent that the dilution air drawn into the PC25C exhaust system
(room air), contained measurable quantities of hydrocarbons. These hydrocarbons presented background
THC emissions that caused a positive bias in the measured PC25C emissions. Therefore, background
sampling was conducted for 10 minutes at the end of each test to quantify the THC concentrations in the
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room air near the dilution air intake. Dilution air flow rate was determined using EPA Method 2 in order
to calculate the mass flow of background THCs. The background THCs were then subtracted from the
THC levels measured in the combined exhaust stack to report the THC emissions directly attributable to
the PC25C. More detail regarding the background THC levels and their impact on the reported emissions
is provided with the test results in Section 2.4.1.
1.4.5. Estimated Annual Emission Reductions
The electric energy generated by the PC25C offsets electricity otherwise supplied by the utility grid.
Consequently, the reduction in electricity demand from the grid caused by this offset will result in
changes in CO2 and NOX emissions associated with producing an equivalent amount of electricity at
central power plants. If the PC25C emissions per kWh are less than the emissions per kWh produced by
an electric utility, it can be inferred that a net reduction in emissions will occur at the site. If the
emissions from the on-site generators are greater than the emissions from the grid, possibly due to the use
of higher efficiency power generation equipment or zero emissions generating technologies at the power
plants, a net increase in emissions may occur. An on-site CHP system used to provide heat as well as
power will also typically create an emissions reduction for the baseline heat source. That is not the case
at this facility, however, because the facility's heat demand is met by a large co-generating facility that
can use the offset heat for other customers. Production of heat by the PC25C at Red Hook will not
change operations at the cogeneration facility and, therefore, no additional emission reductions are
realized.
Use of the PC25C at this facility presents an added environmental benefit by offsetting emissions from
the enclosed flare. ADG used to fuel the PC25C would otherwise be combusted by the flare. An
additional reduction in emissions will be realized under the PC25C system scenario if emissions of CO2
and NOX from the PC25C are lower than the emissions associated with the flare.
Emissions from the PC25C are compared with the baseline scenario to estimate annual NOX and CO2
emission levels and reductions. These pollutants were considered because CO2 is the primary greenhouse
gas emitted from combustion processes and NOX is a primary pollutant of regulatory interest. Emission
factors for the electric utility grid and the flare are available for both gases. Emission reductions are
computed as follows:
Reduction (Ibs) = EQRID + EFLARE - ECHP (Equation 4)
Reduction (%) = (EGRID + EFLARE -ECHp)/(EGRiD + EFLARE) * 100
Where:
Reduction = Estimated annual emission reductions from on-site electricity generation,
Ibs or %
ECHP = Estimated annual emissions from PC25C, Ibs
EGRID = Estimated annual emissions from utility grid, Ibs
EFLARE = Estimated annual emissions from flare, Ibs
The following describes the methodology used.
Step 1 - Estimation of PC25C CO? and NOx Emissions
The first step in calculating emission reductions was to estimate the emissions associated with generating
electricity with ADG at the site over a given period of time (one year), operating at normal site
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conditions. Based on the total electrical generation over the 30-day monitoring period (extrapolated to a
one-year period), and the measured emission rated, the PC25C emissions can be estimate as follows:
ECHP = ERcHp * kWhcHp (Equation 5)
Where:
ECHP = Estimated annual emissions from PC25C fueled with ADG, Ibs
ERCHP = PC25C CO2 or NOX emission rate at full load on ADG, Ib/kWh
WhcHp = Total annual electrical energy generated at the site, kWh
Step 2 - Estimation of Utility Grid Emissions
The grid emission rate (ER^d) is a complex subject, and the methodology for estimating it is
continuously evolving. The TQAP includes a discussion on the concept of displaced emissions and
details the strategy employed by the GHG Center to assign ERond for this verification.
The GHG Center used the emission factors developed by the Ozone Transport Commission (OTC). The
OTC emission factors for this region [the New York State Independent System Operator (NY ISO)
region] are separated into ozone and non-ozone seasons as well as weekdays and night and weekend time
periods. For this verification however, the center was not able to procure detailed facility demand data,
and the PC25C extended monitoring period failed to provide a realistic estimate of annual PC25C
generation (due to numerous outages caused by facility operations at Red Hook). Therefore, time
weighted 2002 average emissions factors for the NY ISO are used here. They are 0.0023 Ib/kWh for
NOX, and 1.49 Ib/kWh for CO2.
Estimated power grid emissions for equivalent power production, therefore, are based on the annual
estimated kilowatt-hours generated by the PC25C, line losses, and the grid emission rates for CO2 or NOX
as shown in Equation 6.
EGR1D = kWhCHP * ERGR1D * 1 . 1 14 (Equation 6)
Where:
EGRID = Annual grid emissions, Ibs
kWhCHp= estimated annual PC25C power generated, kWh
ERoRiD = emission rates from Table 1-4, Ib/kWh
1.078 = Total transmission and distribution losses
Step 3 - Estimate Annual Flare Emissions
Published EPA AP-42 flare emission factors [11] were used to estimate emissions offsets realized through
use of the PC25C. AP-42 provides methodology for estimating the NOX and CO2 emissions from an
enclosed flare based on the amount of gas combusted. The flare emissions will be added to the estimated
annual grid emissions to establish the total facility baseline emission estimate.
The approach used to estimate annual flare emissions is similar to the grid emissions estimate. The
estimated annual ADG combusted in the flare is reduced by the amount of ADG used to fuel the PC25C.
The average PC25C gas consumption rate measured during the verification testing at full load, along with
the projected PC25C hours of operation, was used to estimate the amount of ADG used during a typical
year of PC25C operation.
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2.0 VERIFICATION RESULTS
2.1. OVERVIEW
The verification period started on May 19, 2004, and continued through June 19, 2004. The controlled
tests were conducted on May 19 and 20, and were followed by a 30-day period of continuous monitoring
to examine heat and power output, power quality, efficiency, and emission reductions.
The GHG Center acquired several types of data that represent the basis of verification results presented
here. The following types of data were collected and analyzed during the verification:
• Continuous measurements (ADG pressure, temperature, and flow rate, power output and
quality, heat recovery rate, and ambient conditions)
• ADG compositional data
• Emissions testing data
The field team leader reviewed, verified, and validated some data, such as DAS file data and
reasonableness checks while on site. The team leader reviewed collected data for reasonableness and
completeness in the field. The data from each of the controlled test periods was reviewed on site to verify
that PTC-50 variability criteria were met. The emissions testing data was validated by reviewing
instrument and system calibration data and ensuring that those and other reference method criteria were
met. Calibrations for fuel flow, pressure, temperature, electrical and thermal power output, and ambient
monitoring instrumentation were reviewed on site to validate instrument functionality. Other data such as
fuel LHV analysis results were reviewed, verified, and validated after testing had ended. All collected
data was classified as either valid, suspect, or invalid upon review, using the QA/QC criteria specified in
the TQAP. Review criteria are in the form of factory and on-site calibrations, maximum calibration and
other errors, audit gas analyses, and lab repeatability. Results presented here are based on measurements
which met the specified Data Quality Indicators (DQIs) and QC checks and were validated by the GHG
Center.
The GHG Center attempted to obtain a reasonable set of short-term data to examine daily trends in
atmospheric conditions, electricity and heat production, and power quality. It should be noted that these
results may not represent performance over longer operating periods or at significantly different operating
conditions.
It is the intention of NYPA to operate the PC25Cs at the Red Hook site on a nearly continuous basis.
This was not the case during the verification period however. There were numerous unexpected
shutdowns during the 30-day test period, sometimes lasting several days. There were also periods when
the unit was fueled with natural gas. Over the 30-day monitoring period, a total of only 165 hours were
logged with the PC25C operating on ADG. All of the outages were caused by Red Hook operations,
primarily ongoing work with the plants emergency backup power systems. The PC25C cannot operate
during testing or repair of these systems. The GHG Center is not aware of any shutdowns or outages that
were caused by problems within the PC25C system.
Results of the extended monitoring period presented in the following sections are based solely on the 165
hours during which the PC25C was running on ADG. Data collected while the unit was down or
operating on natural gas are not included in this report.
2-1
-------
Test results are presented in the following subsections:
Section 2.1 - Heat and Power Production Performance
(controlled test periods and extended monitoring)
Section 2.2 - Power Quality Performance
(extended monitoring)
Section 2.3 - Emissions Performance and Reductions
(controlled test periods)
The results show that the PC25C produces high quality power and is capable of operating in parallel with
the utility grid. The unit can produce a steady 193 kW of electrical power when fueled with ADG and set
at a power command of 200 kW. The largest production rate of available heat measured during the
extended monitoring period was approximately 1,027 x 103Btu/hr. Electrical efficiency at full load
averaged 36.8 percent. Because the Red Hook site does not use the waste heat, actual thermal efficiency
could not be determined. However, if all of the available heat that was removed by the cooling module
was recovered, thermal efficiency would be 56.9 percent and total CHP efficiency would be 93.8 percent.
NOX emissions averaged 0.013 Ib/MWh at full load. Emissions of CO and hydrocarbons were also very
low during all test periods. Based on these measured generation and emission rates, annual NOX emission
reductions are estimated to be 890 pounds. CO2 emission reductions realized by using ADG to fuel the
PC25C instead of flaring an equivalent amount of ADG are estimated to be 337 tons. Detailed analyses
are presented in the following sections.
In support of the data analyses, the GHG Center conducted an audit of data quality (ADQ) following
procedures specified in the QMP. A full assessment of the quality of data collected throughout the
verification period is provided in Section 3.0.
2.2. HEAT AND POWER PRODUCTION PERFORMANCE
The heat and power production performance evaluation included electrical power output, heat recovery,
and CHP efficiency determinations during controlled test periods. The performance evaluation also
included determination of total electrical energy generated and used and available thermal energy
produced over the extended test period.
2.2.1. Electrical Power Output, Heat Production, and Efficiency During Controlled Tests
Figure 2-1 plots the power generated and heat produced by the PC25C during the controlled test periods.
Table 2-1 summarizes the power output, available heat, and efficiency performance of the CHP system.
The PC25C heat recovery unit operations and ADG fuel input determinations corresponding to the test
results are summarized in Tables 2-2 and 2-3. A total of 6 ADG samples were collected for
compositional analysis and calculation of LHV for heat input determinations. There was very little
variability in the ADG composition. Average CH4 and CO2 concentrations of the ADG (after processing)
were 61.4 and 37.1 percent, respectively. The average LHV was 552 Btu/scf and H2S concentrations
were below the method detection limit (4 parts per billion). H2S concentrations in the 6 corresponding
raw ADG samples averaged 93 ppm. More detail regarding the composition of the raw ADG and the
performance of the GPU are provided in a separate report [6].
Figure 2-1 shows that power output is very stable at each of the three power commands. Heat production
is also stable, but short-term variability is caused by cycling of the variable speed water circulation pump.
The average net electrical power delivered to the facility was 193.1 kWe at full load. The average
2-2
-------
electrical efficiency at this power command was 36.8 percent. Electrical efficiencies at the 150 and 100
kW power commands averaged 38.2 and 37.4 percent, respectively. Electric power generation heat rate,
which is an industry-accepted term to characterize the ratio of heat input to electrical power output,
averaged 9,148 Btu/kWh at full load.
As mentioned earlier in Section 1.4, the Red Hook plant uses heat from a neighboring cogeneration plant
to meet its demand, and currently demands very little or no heat from the PC25C. Most or all of the heat
generated by the PC25C is removed through the cooling module to protect the system from overheating.
During Runs 1 and 2, some heat was recovered by the CHP system. However, due to plant operating
requirements, during the remainder of the runs and the extended monitoring period, no heat was
recovered. Therefore, the potential thermal performance shown in Figure 2-1 and summarized in Table 2-
1 is actually the combination of heat recovered and used by Red Hook (during Runs 1 and 2 only), and
the heat removed through the cooling module. The total available heat produced (that is, the heat
recovery and removal rates for the two loops) is summarized in Table 2-2. The center was not able to
verify whether all of the heat produced and removed by the cooling module could be recovered for actual
use if sufficient demand existed.
200
1400
-- 1200
i- 1000
I
PQ
•o
2
200 kW Power
Command
150 kW Power
Command
100 kW Power
Command
Figure 2-1. Power and Heat Production During the Controlled Test Periods
The total heat produced at full load averaged 1,018 103Btu/hr, or 298.3 kWth/hr. If all of this available
heat were recovered and used, the estimated thermal efficiency would be 56.9 percent. The total CHP
efficiency (electrical and thermal combined) would be 93.8 percent under these conditions. It should be
noted that thermal efficiency is highly dependant on cooling loop return temperatures. Return
temperatures from the cooling module were relatively low, so it is likely that thermal efficiency will be
lower when heat recovery system return temperatures are higher than seen here. The net CHP heat rate,
which includes energy available for heat recovery, was 3,678 Btu/kWh. Results of the reduced load tests
are also included in the tables. Results show that electrical efficiency is consistent as the power output is
reduced. The available heat is significantly reduced at lower power settings.
2-3
-------
Table 2-1. PC25C Heat and Power Production Performance
Test ID
Runl
Run 2
Run 3
Avg.
Run 4
Run 5
Run 6
Avg.
Run?
Run8
Run 9
Avg.
Test
Condition
200 kW
power
command
150 kW
power
command
100 kW
power
command
Heat
Input, HI
(103Btu/hr)
1,791
1,789
1,787
1,789
1,364
1,352
1,360
1,359
907.2
952.1
924.4
927.9
Electrical Power Generation
Performance
Power
Delivered a
(kWe)
193.1
193.1
193.0
193.1
152.3
152.2
152.3
152.3
101.5
101.5
101.5
101.5
Efficiency
(%)
36.8
36.8
36.9
36.8
38.1
38.4
38.2
38.2
38.2
36.4
37.5
37.4
Heat Recovery Performance
Heat Recovered /
Removed1"
(103Btu/hr)
131/883
121/883
0.4/1,036
84.1/994
-2.0/717
0.0/690
-0.1/696
-0.7 / 701
-0.1/468
-0.1/513
-0.1/460
-0.1/480
Thermal
Efficiency (Actual
/Potential, %)c
7.3/56.6
6.8/56.2
0.0/58.0
4.7 / 56.9
0.0/52.4
0.0/51.0
0.0/51.2
0.0 / 51.5
0.0/51.5
0.0/53.8
0.0/49.7
0.0/51.7
Total CHP
System Efficiency
(Actual /
Potential, %)c
44.1/93.4
43.6/93.0
36.9/94.9
41.5 / 93.8
38.1/90.5
38.4/89.4
38.2/89.4
38.2 / 89.8
38.2/89.7
36.4/90.2
37.5/87.2
37.4 / 89.0
Ambient Conditions d
Temp (°F)
82.3
82.1
77.7
80.7
75.6
75.2
78.0
76.3
80.0
79.3
78.4
79.2
RH (%)
50.7
53.6
57.1
53.8
55.2
44.1
34.5
44.6
19.7
27.4
29.0
25.4
a Represents actual power available for consumption at the test site (net power).
b Divide by 3.412 to convert to equivalent kilowatts (kW).
0 Actual thermal and CHP efficiency is based on the heat recovered during the testing at the Red Hook plant. Potential thermal and CHP efficiency is estimated by assuming that all available
heat is utilized in a heat recovery application.
d Barometric pressure remained relatively consistent throughout the test runs (14.82 to 14.95 psia).
2-4
-------
Table 2-2. PC25C Heat Recovery Unit and Cooling Module Operating Conditions
Test ID
Runl
Run 2
Run 3
Avg.
Run 4
Run 5
Run 6
Avg.
Run?
Run8
Run 9
Avg.
Test
Condition
200 kW
power
command
150 kW
power
command
100 kW
power
command
Hot Water Header Heating Loop
Fluid Flow
Rate,Vb
(GPM)
20.1
20.1
0.25
13.5
0.42
0.68
0.73
0.61
0.72
0.11
0.62
0.49
Outlet
Temp.,
Tlb (°F)
180.2
182.4
147.2
169.9
128.4
100.3
96.8
108.5
96.1
61.9
87.4
81.8
Inlet
Temp., T2b
(°F)
166.8
169.9
144.8
160.2
138.0
100.2
97.0
111.7
96.5
64.5
88.0
83.0
Heat
Recovery
Rate
(103Btu/hr)
130.6
121.3
0.42
84.1
-2.00
0.03
-0.07
-0.68
-0.14
-0.14
-0.14
-0.14
Cooling Module Loop
Fluid Flow
Rate, Va
(GPM)
22.3
21.6
25.9
23.3
16.3
15.4
15.7
15.8
11.9
11.9
11.7
11.8
Outlet
Temp., Tla
(°F)
167.3
169.2
171.6
169.5
175.5
176.3
176.5
176.3
165.8
174.0
165.9
168.6
Inlet
Temp., T2a
(°F)
87.1
86.7
90.6
88.1
86.2
86.2
86.8
86.4
86.3
86.4
86.3
86.4
Heat
Removal
Rate
(103Btu/hr)
882.8
883.2
1,035.9
994.0
716.5
690.2
695.9
700.9
467.6
512.5
459.6
479.9
Total
Available
Heat
(103Btu/hr)
1,013.4
1,004.6
1,036.3
1,018.1
714.5
690.3
695.9
700.2
467.4
512.3
459.5
479.7
2-5
-------
Table 2-3. PC25C Heat Input Determinations
Test ID
Runl
Run 2
Run3
Avg.
Run 4
Run 5
Run 6
Avg.
Run?
Run8
Run 9
Avg.
Test Condition
200 kW power
command
1 50 kW power
command
100 kW power
command
ADG Fuel Input
Heat Input ,
HI
(103Btu/hr)
1,791
1,789
1,787
1,789
1,364
1,352
1,360
1,359
907.2
952.1
924.4
927.9
Gas Flow
Rate (scfm)
53.8
53.7
53.6
53.7
41.1
40.6
40.8
40.8
27.5
28.9
28.0
28.1
LHV
(Btu/scf)
555.3
555.3
555.3
555.3
552.8
555.7
555.7
554.7
549.4
549.4
549.4
549.4
Gas Pressure
(psia)
16.2
16.2
16.2
16.2
15.7
15.8
15.8
15.8
15.7
15.7
15.7
15.7
Gas Temp
(°F)
81.2
81.6
81.6
81.5
80.4
77.4
77.7
78.5
77.4
77.3
77.1
77.3
2.2.2. Electrical and Thermal Energy Production and Efficiency During the Extended Test
Period
Figure 2-2 presents a time series plot of 1-minute average power and heat production and ADG
consumption during the extended verification period. As described earlier, although the extended
monitoring period spanned 30 days, the PC25C was operating on ADG for only 165 hours during that
period. Periods of down time or operation on natural gas (usually only during system startup) are not
included in any of the figures and analyses presented here.
A total of 27,748 kWhe electricity and 35,296 kWhth of thermal energy (or 120.4 x 106Btu) were
generated from ADG during the 165 hours of operation. The power generating plot in Figure 2-2 shows
that power output is very stable at a variety of power commands ranging from 100 to 200 kW. The
stability of power output over these extended periods of operation indicates that PC25C performance is
not affected by external variables such as ambient conditions or fuel quality. Since the PC25C was not
always operated at full load, the average power generated over the extended period was 166 kWe. Heat
production is more variable than power output, but the amount of heat produced by the fuel cell correlates
with power output. The figure shows that ADG consumption is also very stable at each power command.
Figure 2-2 shows a short interruption in power generation that occurred while the unit was operating on
ADG. The data show that at 11:31 on May 21, PC25C power output decreased from 101 kW through
zero, and began consuming between 13 and 35 kW of power until about 12:06. By 12:27, the fuel cell
had ramped back up to 177 kW. This event also is apparent in the power factor and THD data (Figures 2-
5 and 2-6). Operators were not able to provide and explanation of this event.
2-6
-------
320
Shaded areas represent periods of unreported data
due to shutdowns or plant upsets
05/20/04
(17:00) '
30-Day Monitoring Period
06/19/04
• (11:48)
Figure 2-2. Heat and Power Production During the Extended Monitoring Period
Figure 2-3 shows hourly average PC25C electrical, thermal, and total CHP efficiencies during the
extended monitoring period. Efficiency throughout the period was consistent with those measured during
the controlled test periods.
Potential
CHP
100
.—
"jj
0
05/20/04
(17:00) •*-
30-Day Monitoring Period
06/19/04
-»• (11:48)
2-7
-------
Figure 2-3. PC25C Efficiency During the Extended Monitoring Period
2.3. POWER QUALITY PERFORMANCE
Figures 2-4 through 2-6 plot the PC25C power quality for the period including voltage, frequency, power
factor, and THD. Table 2-4 summarizes the power quality statistics.
460
05/20/04
(17:00) •*•
60.20
30-Day Monitoring Period
59.90
06/19/04
-*• (11:48)
Figure 2-4. PC25C Voltage and Frequency During the Extended Monitoring Period
102 T
100 -•
96 -
94 -
£ 92 --
90 -
05/20/04,
(17:00) '
"*** Power event on
05/21/04 (see text)
Power factors shown as absolute
values and were all negative after
06/10/04 (PC25 acting as a VAR
source).
30-Day Monitoring Period
06/19/04
" (11:48)
Figure 2-5. PC25C Power Factor During the Extended Monitoring Period
2-S
-------
05/20/04
(17:00) '
30-Day Monitoring Period
0.0
06/19/04
.- (11:48)
Figure 2-6. PC25C Current and Voltage THD During the Extended Monitoring Period
Table 2-4. Summary of PC25C Power Quality
Parameter
Voltage (volts)
Frequency (Hz)
Power Factor3 (%)
Power Factorb (%)
Current THD (%)
Voltage THD (%)
Average
487.6
60.00
7.22
93.41
12.50
2.29
Maximum
Recorded
498.4
60.08
100
100
309.1"
3.93
Minimum
Recorded
457.2
59.93
-99.99
86.14
0.00
1.31
Standard
Deviation
3.81
0.017
93.37
6.62
7.10
0.45
a Average power factor is misleading due to both positive and negative power factors recorded (see
discussion).
b Power factors summarized as absolute values for simplicity (as in Figure 2-5).
0 High current THDs were recorded during power event on May 21 when current was very low. Highest
current THD during stable operation was 40.1 percent.
The voltage and frequency of the power generated by the PC25C were stable and in the range expected
(Figure 2-4). Figure 2-5 shows power factor as absolute values for simplicity. During the first portion of
the extended monitoring period, the fuel cell produced power at near unity (about 99.7 percent) positive
power factor. After the second data interruption, however, average power factor was approximately 88.5
percent negative and remained so for the balance of the monitoring period. The cause of this change in
power factor could not be determined because the PC25C is not isolated from the grid or sources of
2-9
-------
electrical load within the plant. Both will impact the unit's power factor depending on plant operations
and load.
Voltage THD was low during the entire verification period and well within the IEEE recommendation of
5 percent. Current THD averaged 12.5 percent and exceeded the IEEE recommended limit on several
occasions. The highest values observed were during the power down event previously discussed.
2.4. EMISSIONS PERFORMANCE
2.4.1. PC25C Exhaust Emissions
Stack emission measurements were conducted during each of the controlled test periods summarized in
Table 1-1. All testing was conducted in accordance with the EPA reference methods listed in Table 1-2.
The PC25C was maintained in a stable mode of operation during each test run based on PTC-50
variability criteria.
Emissions results are reported in units of parts per million volume dry, corrected to 15-percent O2 (ppm at
15-percent O2) for NOX, CO, and THC. Concentrations of CO2 are reported in units of volume percent,
and TPM concentrations are reported as grains per dry standard cubic foot (gr/dscf). These pollutant
concentration data were converted to mass emission rates using measured exhaust stack flow rates and are
reported in units of pounds per hour (Ib/hr). The emission rates are also reported in units of pounds per
megawatt hour electrical output (lb/kMWhe). They were computed by dividing the mass emission rate by
the electrical power generated during each test run.
Sampling system QA/QC checks were conducted in accordance with TQAP specifications to ensure the
collection of adequate and accurate emissions data. These included analyzer linearity tests, sampling
system bias and drift checks, and sampling train leak checks. Results of the QA/QC checks are discussed
in Section 3. The results show that DQOs for all gas species met the reference method requirements.
Table 2-5 summarizes the emission rates measured during each run and the overall average emissions for
each set of tests.
In general, PC25C emissions of each of the pollutants quantified were very low during all test periods.
NOX concentrations in the combined exhaust stack were consistent throughout the range of operation
averaging 0.43 ppm at 15% O2 at full power command and 0.41 ppm at 15% O2 at the lowest load tested.
The average NOX emission rate at full power, normalized to power output, was 0.013 Ib/MWh.
Exhaust gas CO concentrations averaged 1.64 ppm at 15% O2 at full load and increased to an average
4.14 ppm at 15% O2 at the 100 kW power command. Corresponding average CO emission rates at full
load averaged 0.029 Ib/MWh.
2-10
-------
Table 2-5. PC25 Emissions During Controlled Test Periods
Run 1a
Run 2
Run3
AVGb
Run 4
Run5
Run 6
AVG
Run 7
Run8
Run 9
AVG
its-
IBl
193.1
193.1
193.0
193.1
152.3
152.2
152.3
152.3
101.5
101.5
101.5
101.5
Exhaust
02 (%)
8.7
19.3
19.5
19.4
19.8
19.8
19.7
19.8
20.1
20.1
20.2
20.1
CO Emissions
(ppm at
15% O2)
0.35
1.59
1.69
1.64
1.07
4.29
2.95
2.77
3.69
3.69
5.06
4.14
Ib/hr
1 .38E-03
6.04E-03
5.24E-03
5.64E-03
2.62E-03
1.19E-02
8.69E-03
7.74E-03
7.24E-03
7.59E-03
8.83E-03
7.89E-03
Ib/MWh
7.15E-03
3.13E-02
2.72E-02
2.92E-02
1.72E-02
7.83E-02
5.71 E-02
5.09E-02
7.13E-02
7.47E-02
8.70E-02
7.77E-02
NOX Emissions
(ppm at
15% O2)
0.26
0.39
0.47
0.43
0.43
0.53
0.36
0.44
0.38
0.44
0.42
0.41
Ib/hr
1 .68E-03
2.45E-03
2.41 E-03
2.43E-03
1.74E-03
2.42E-03
1.76E-03
1.98E-03
1 .21 E-03
1 .47E-03
1 .21 E-03
1.30E-03
Ib/MWh
8.72E-03
1 .27E-02
1 .25E-02
1.26E-02
1.15E-02
1 .59E-02
1.16E-02
1.30E-02
1 .20E-02
1 .45E-02
1.19E-02
1.28E-02
THC Emissions0
(ppm at
15% O2)
5.80
80.0
160
120
266
338
157
254
226
189
244
220
Ib/hr
0.01
0.10
0.21
0.15
0.20
0.27
0.15
0.21
0.11
0.10
0.21
0.14
Ib/MWh
0.07
0.50
1.06
0.78
1.32
1.79
0.95
1.36
1.12
0.95
2.03
1.37
CH4 Emissions0
(ppm at
15% O2)
7.50
82.2
162
122
254
343
157
250
209
189
212
203
Ib/hr
0.02
0.10
0.21
0.16
0.18
0.28
0.15
0.21
0.09
0.10
0.17
0.12
Ib/MWh
0.09
0.52
1.09
0.80
1.21
1.84
0.96
1.40
0.92
0.95
1.70
1.19
CO2 Emissions
%
9.8
1.3
1.3
1.3
0.9
0.8
1.0
0.9
0.6
0.6
0.7
0.6
Ib/hr
295.5
287.1
267.8
277.4
185.4
187.3
227.8
200.1
136.6
143.1
162.0
147.2
Ib/MWh
1530
1487
1387
1437
1217
1231
1495
1314
1346
1410
1596
1451
3 Run 1 was conducted in the reformer exhaust duct and represents reformer emissions only.
1 Average of Runs 2 and 3 only, which were conducted in the combined exhaust gas duct and represent emissions to atmosphere.
= Reported THC and CH4 emission rates in units of Ib/hr and Ib/MWh are corrected for background contributions of THC in the PC25 dilution air. Reported emissions are not corrected for background
contributions in the power plant air intake.
2-11
-------
Quantification of THC and CH4 emissions was complicated by the background hydrocarbons in the
ambient air that were drawn into the PC25C exhaust system by the dilution air fan. The center attempted
to correct measured exhaust stack emissions for this contamination by measuring the background THC
concentrations before and after each test run and measuring the volumetric flow of dilution air. The mass
flow of THC through the system was then subtracted from the THC and CH4 emission rates measured in
the stack. The reported emission rates summarized in Table 2-5 (Ib/hr and Ib/MWh) represent the
corrected emission rates. These corrections do not however account for hydrocarbons drawn into the
system at the fuel cell stack. Reported hydrocarbon emissions ranged from 0.78 Ib/MWh at full load to
1.37 Ib/MWh at the 100 kW power setting. The reader is warned however, that the THC and CHt
emission rates presented here are still much higher than what has been reported on other PC25C emission
tests. In three previous tests on other PC25Cs, the highest measured THC emission rate was 0.02
Ib/MWh. One test of particular interest was conducted at a similar facility, by the same test crew, on a
new PC25C using anaerobic digester gas. THC emissions for that unit (an outdoor installation) were less
than 0.011 Ib/MWh. It is likely that results presented here were biased high by the background
hydrocarbons in the building. More detail regarding the results from other tests is provided by UTC in
Section 4.0 of this report. Background concentrations of the other pollutants were insignificant.
Concentrations of CO2 in the PC25C exhaust gas averaged 1.3 percent at full power and decreased to a
low of 0.6 percent as power output was reduced. These concentrations correspond to average CO2
emission rates of 1,437 and 1,451 Ib/MWh, respectively.
2.4.2. Estimation of Annual NOX and CO2 Emission Reductions
Section 1.4.5 outlined the approach for estimating the annual emission reductions that may result from
use of the PC25C and ADG at this facility. The detailed approach is provided in the TQAP.
Step 1 - Annual PC25C Emissions
The first step is to estimate annual PC25C NOX and CO2 emissions based on data generated during this
verification. The average NOX and CO2 emission rates at full load were 0.126 and 1,437 Ib/MWh,
respectively. The power delivered by the PC25C during the 30-day verification period (27.75 MW),
results in an estimated annual generating rate of 337.6 MW. These values result in estimated annual NOX
and CO2 emissions of 0.021 and 243 tons per year (ton/yr) of NOX and CO2, respectively.
These estimates are conservatively low given the excessive PC25C downtime and outages during the 30-
day monitoring period that were caused by facility operations. The GHG Center conducted verification
testing on a similar PC25C at a landfill and verified availability at 97 percent [12]. Based on this
availability and the average generating rate measured during the verification (166 kW), the annual
estimated potential PC25C generation with ADG is estimated to be at least 1,411 MW. For the benefit of
potential users of the PC25C where ADG or other types of biogas are available, this report will also
estimate hypothetical annual emission reductions based on this expected generation rate. For the PC25C
tested here, the annual NOX and CO2 emissions (assuming 97 percent availability) are then 0.088 and
1,014 ton/yr, respectively.
Step 2 - Utility Grid Emissions
The average NY ISO NOX and CO2 emission rates published by OTC and used here are 2.30 and 1,490
Ib/MWh, respectively. Based on the measured PC25C generating rate described above, the annual
estimated NOX and CO2 emissions for an equivalent amount of power from the grid are 0.399 and 252
2-12
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ton/yr, respectively. Based on the hypothetical potential generating rate described above, the annual
estimated NOX and CO2 emissions for an equivalent amount of power from the grid are 1.63 and 1,051
ton/yr, respectively.
Step 3 - Annual Flare Emissions
The procedures provided in AP-42 to estimate NOX and CO2 emissions from the enclosed flare were used
to estimate flare emissions caused by combusting an amount of ADG equivalent to the amount used to
fuel the PC25C, had the PC25C not been operating. Consistent with the emission reductions
determinations for power production, flare emissions were determined using two scenarios. Specifically,
flare emissions were estimated based on the amount of ADG consumed by the PC25C during the
verification period, and based on the hypothetical case where the PC25C is available and operates on
ADG 97 percent of the time.
Based on PC25C operations during the verification period, the PC25C is projected to operate 2,007 hours
per year at an average 166 kW electrical generation. Using the ADG consumption rates measured during
the verification, this scenario results in an estimated annual ADG consumption of 5.432 million standard
cubic feet per year (106scf/yr). Following AP-42 procedures for estimating emission factors, this amount
of ADG combusted in the flare will result in estimated NOX and CO2 emissions of 0.067 and 328 ton/yr,
respectively.
Using the hypothetical case, the PC25C is projected to operate 8,497 hours per year at 166 kW. Using the
ADG consumption rates measured during the verification, this scenario results in an estimated annual
ADG consumption of 22.99 MMscf/yr. This amount of ADG combusted in the flare will result in
estimated NOX and CO2 emissions of 0.282 and 1,389 ton/yr, respectively.
Step 4 - Determination of Estimated Emission Reductions
Estimated annual NOX and CO2 emissions for the two operational scenarios described are summarized in
Table 2-6. For both scenarios, significant reductions in pollutant emissions were observed.
Table 2-6. Estimation of PC25C Emission Reductions
Operating
Scenario
(annual hours
of Operation)
2,007a
8,497b
Annual
PC25C
Emissions (tons)
NOX
0.021
0.088
CO2
243
1014
Baseline Case (Red Hook Without PC25C)
Annual Emissions (tons)
Grid
Emissions
NOX
0.399
1.63
CO2
252
1051
Flare
Emissions
NOX
0.067
0.282
CO2
328
1389
Total
Emissions
NOX
0.466
1.91
CO2
580
2440
Estimated Annual
Emission Reductions
(tons)
NOX
0.445
1.82
CO2
337
1426
a Based on the PC25C availability during the verification period, and the average measured power output of 166 kW.
b Based on the expected PC25C availability of 97 percent, and the average measured power output of 166 kW.
It should be noted that the measured CFLj emission rate for the PC25C was 0.80 Ib/MWh, higher than the
utility grid CFI4 emission factor of 0.10 Ib/MWh. Assuming the flare is 100 percent efficient, the PC25C
would introduce an overall increase in CFI4 emissions. This increase will offset a small portion of the
CO2 emission reductions based on carbon equivalents (less than 1 percent of the CO2 reductions shown in
Table 2-6 would be offset by the increase in CFI4 emissions).
2-13
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3.0
DATA QUALITY ASSESSMENT
3.1. DATA QUALITY OBJECTIVES
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. Similar PEAs were recently conducted on two
similar CHP verifications [13, 14] and it was decided to not repeat the PEA a third time. Finally, a
readiness and planning review was conducted by the QA manager. During the readiness and planning
review, the QA Manager confirmed that the field measurements and activities conformed to the approved
TQAP.
The GHG Center selects methodologies and instruments for all verifications to ensure a stated level of
data quality in the final results. The GHG Center specifies data quality objectives (DQOs) for each
verification parameter before testing commences. Each test measurement that contributes to the
determination of a verification parameter has stated data quality indicators (DQIs) which, if met, ensure
achievement of that verification parameter's DQO.
Table 3-1. Verification Parameter Data Quality Objectives
Verification Parameter
Original DQO Goal3
Relative (%) /Absolute (units)
Achieved1"
Relative (%) /Absolute (units)
Power and Heat Production Performance
Electrical power output (kW)
Electrical efficiency (%)
Heat recovery rate (103Btu/hr)
Thermal energy efficiency (%)
CHP production efficiency (%)
±1.0%/2.0kW
±1.6%/0.56%c
±1.7% / 14 103Btu/hrrc
±1.7%/0.7%c
±2.3%/1.7%c
±1.0%/1.9kW
±3.3%/1.2%c
±1.9% 119 103Btu/hrc
±3.7%/2.1%c
± 2.5% / 2.4%c
Power Quality Performance
Electrical frequency (Hz)
Voltage
Power factor (%)
Voltage and current total harmonic distortion (THD)
(%)
± 0.01% / 0.006 Hz
± 1.0 %/ 4.85 Vc
± 0.50% / TBD
± 1.0% /TBD
± 0.01% / 0.006 Hz
± 1.0 %/ 4.88 Vc
± 0.50% / 0.47%
±1.0%/0.01%
Emissions Performance
NOX, CO, CO2, and O2, concentration accuracy
THC and CH4 concentration accuracy
±2.0%ofspand
±5.0%ofspand
±2.0%ofspand
±5.0%ofspand
a Original DQO goals as stated in TQAP. Absolute errors were provided in the TQAP, where applicable, based on anticipated values.
b Overall measurement uncertainty achieved during verification. The absolute errors listed are based on these uncertainties, and the
average values measured during the verification
0 Calculated composite errors were derived using the procedures described in the TQAP.
d Qualitative data quality indicators based on conformance to reference method requirements.
The establishment of DQOs begins with the determination of the desired level of confidence in the
verification parameters. Table 3-1 summarizes the DQOs established in the test planning stage for each
verification parameter. The actual data quality achieved during testing is also shown. The next step is to
identify all measured values which affect the verification parameter and determine the levels of error
3-1
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which can be tolerated. These DQIs, most often stated in terms of measurement accuracy, precision, and
completeness, are used to determine if the stated DQOs are satisfied. The DQIs for this verification-used
to support the DQOs listed in Table 3-1-are summarized in Table 3-2.
The DQIs specified in Table 3-2 contain accuracy, precision, and completeness levels that must be
achieved to ensure that DQOs were met. Reconciliation of DQIs is conducted by performing independent
performance checks in the field with certified reference materials and by following approved reference
methods, factory calibrating the instruments prior to use, and conducting QA/QC procedures in the field
to ensure that instrument installation and operation are verified. The following sections address
reconciliation of each of the DQI goals.
3.2. RECONCILIATION OF DQOs AND DQIs
Table 3-2 summarizes the range of measurements observed in the field and the completeness goals.
Completeness is the number or percent of valid determinations actually made relative to the number or
percent of determinations planned. The completeness goals for the controlled tests were to obtain
electrical and thermal efficiency as well as emission rate data for three test runs conducted at each of three
different load conditions. This completeness goal was achieved.
Completeness goals for the extended tests were to obtain 90 percent of 2 to 4 weeks of power quality,
power output, heat recovery rate, and ambient measurements. Although 30 complete days of valid data
were collected during the verification, the PC25C was shut down for much of this period in response to
plant operating problems. During this period, 23 percent of the data was collected while the unit was
running and was useful in establishing trends in power and heat performance capability at varying
ambient temperatures as discussed in Section 2.0.
Table 3-2 also includes accuracy goals for measurement instruments. Actual measurement accuracies
achieved are also reported based on instrument calibrations conducted by manufacturers, field
calibrations, reasonableness checks, and/or independent performance checks with a second instrument.
Table 3-3 includes the QA/QC procedures that were conducted for key measurements in addition to the
procedures used to establish DQIs. The accuracy results for each measurement and their effects on the
DQOs are discussed below.
3-2
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Table 3-2. Summary of Data Quality Indicator Goals and Results
Measurement Variable
Power Output
and Quality
Heat
Recovery
Rate
Ambient
Conditions
Power
Voltage
Frequency
Current
Voltage THD
Current THD
Power Factor
Inlet
Temperature
Outlet
Temperature
Water Flow
Ambient
Temperature
Ambient
Pressure
Relative
Humidity
Instrument
Type/
Manufacturer
Electric Meter/
Power
Measurements
7500 ION
Controlotron
Model 1010EP
RTD/Vaisala
Model HMD
60YO
Setra Model
280E
Vaisala Model
HMD 60 YO
Instrument
Range
0 to 400 kW
0 to 600 V
55 to 65 Hz
0 to 400A
0 to 100%
0 to 100%
0 to 100%
-18 to 149 °C
-18 to 149 °C
Oto 150GPM
-50 to 150°F
0 to 25 psia
0 to 100% RH
Range
Observed in
Field
Oto 193. 5 kW
457 to 498V
59.9 to 60.1 Hz
123 to 250 A
1.3 to 3. 9%
0.0 to 40.1%
86.1 to 100%
27 to 41 °C
65 to 89 °C
12 to 44 GPM
70 to 93 °F
14. 57 to 14.67
psia
19 to 65% RH
Accuracy
Goal
± 1.0% reading
± 1 .0% reading
± 0.01% reading
± 1 .0% reading
± 1.0% full scale
± 1.0% full scale
± 0.5% reading
Temps must be ±
0.8°Cofref.
Thermocouples,
each
± 1.0% reading
± 0.2 °F
±0-1% full scale
± 2%
Actual
± 1.0% reading
± 1.0% reading
± 0.01% reading
± 1.0% reading
± 1.0% full scale
± 1.0% full scale
± 0.5% reading
± 0.8 °C for delta
T
± 0.1% reading
± 0.2 °F
± 0.05% full scale
± 0.2%
How Verified /
Determined
Biennial instrument
calibration from
manufacturer
Independent check
with calibrated
thermocouple
Biennial instrument
calibration from
manufacturer
Instrument
calibration from
manufacturer prior to
testing
Completeness
Goal
Controlled
tests: three
valid runs per
load meeting
PTC 50
criteria.
Extended
test: 90% of
one-minute
readings for 2
weeks.
Actual
Controlled
tests: three
valid runs per
load meeting
PTC 50
criteria.
Extended
test: 100% of
one-minute
readings for
30 days.
(continued)
3-3
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Table 3-2. Summary of Data Quality Indicator Goals and Results (continued)
Measurement Variable
Fuel Input
Exhaust
Stack
Emissions
Gas Flow Rate
Gas Pressure
Gas
Temperature
LHV
NOx Levels
CO Levels
THC Levels
CH4 Levels
O2 Levels
CO2 Levels
Instrument Type /
Manufacturer
Dresser-Roots
Model 5M175 SSM
Series B3 rotary
displacement
Omega Model
PX205-030AI
transducer
Omega TX-93 Type
K thermocouple
Gas Chromatograph
/HP 5890 11
Chemiluminescent/
TECO 42 CH
NDIR / TECO
Model 48
FID/California 300
GC/FID HP 5890
Paramagetic/
Servomex
NDIR/Servomex
Instrument
Range
0 to 83 scfm
0 to 30 psia
0 to 200 °F
0 to 100% CH4
Oto2.5ppm
0 to 10 ppm
0 to 100 ppmv
0 to 100 ppmv
0 to 25%
0 to 20%
Measurement
Range
Observed
9 to 59 scfm
14. 8 to 16.3 psia
74 to 85 °F
60.9 to 61.9%
CH4
547 to 556
Btu/scf
0.05 to 0.53 ppm
0.20 to 0.72 ppm
12 to 63 ppmv
15 to 64 ppmv
8.7 to 20.2%
0.6 to 9.8%
Accuracy
Goal
1.0% of
reading
± 0.75% full
scale
± 0.10% full
scale
±3.0%
accuracy, ±
0.2%
repeatability
0.1%
repeatability
± 2% full scale
± 2% full scale
± 5% full scale
± 5% full scale
± 2% full scale
± 2% full scale
Actual
± 0.5% of
reading
± 0.25% full
scale, 0.075 psia,
0.5 % reading
± 0.10% full
scale, 0.2 °F, 0.2
% reading
± 0.5% accuracy,
± 0.05%
repeatability
± 0.05%
repeatability
< 2% full scale
< 2% full scale
< 5% reading
< 5% reading
< 2% full scale
< 2% full scale
How Verified /
Determined
Factory calibration with
volume prover
Instrument calibration to
NIST traceable standards
analysis of NIST-traceable
CH4 standard, and
duplicate analysis on 3
samples
Conducted duplicate
analyses on 3 samples
Calculated following EPA
Reference Method
calibrations (Before and
after each test run)
Completeness
Goal
Controlled
tests: three
valid runs
per load
meeting
PTC 50
criteria.
Extended
test: 90% of
one-minute
readings for
2 weeks.
Controlled
tests: two
valid
samples per
load
Controlled
tests: three
valid runs
per load.
Actual
Controlled
tests: three
valid runs
per load
meeting
PTC 50
criteria.
Extended
test: 100%
of one-
minute
readings
for 30
days.
Controlled
tests: two
valid
samples
per load
Controlled
tests:
three valid
runs per
load.
3-4
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3.2.1. Power Output
Instrumentation used to measure power was introduced in Section 1.0 and included a Power
Measurements Model 7500 ION. The data quality objective for power output was ±1.5 percent of
reading, which includes compounded error of the instrument and the CTs. The TQAP specified factory
calibration of the ION meter with a NIST-traceable standard to determine if the power output DQO was
met. The TQAP also required the GHG Center to perform several reasonableness checks in the field to
ensure that the meter was installed and operating properly. The following summarizes the results.
The meter was factory calibrated by Power Measurements in April 2003. Calibrations were conducted in
accordance with Power Measurements' standard operating procedures (in compliance with ISO
9002:1994) and are traceable to NIST standards. The meter was certified by Power Measurements to
meet or exceed the accuracy values summarized in Table 3-2 for power output, voltage, current, and
frequency. NIST-traceable calibration records are archived by the GHG Center. Pretest factory
calibrations on the meter indicated that accuracy was within ± 0.05 percent of reading and this value,
combined with the 1.0-percent error inherent to the current transformers resulted in an overall error of ±
1.0-percent. Using the manufacturer-certified calibration results and the average power output measured
during the full-load testing, the error during all testing is determined to be ± 1.9 kW.
Additional QC checks were performed on the 7500 ION to verify the operation after installation of the
meters at the site and prior to the start of the verification test. The results of these QC checks
(summarized in Table 3-3) are not used to reconcile the DQI goals, but to document proper operation in
the field. Current and voltage readings were checked for reasonableness using a hand-held Fluke
multimeter. These checks confirmed that the voltage and current readings between the 7500 ION and the
Fluke were within the range specified in the TQAP as shown in Table 3-3.
These results led to the conclusion that the 7500 ION was installed and operating properly during the
verification test. The ± 1.0-percent error in power measurements, as certified by the manufacturer, was
used to reconcile the power output DQO (discussed above) and the electrical efficiency DQO (discussed
in Section 3.2.2).
3-5
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Table 3-3. Results of Additional QA/QC Checks
Measurement
Variable
Power Output
Fuel Flow Rate
Fuel Heating
Value
Heat Recovery
Rate
QA/QC Check
Sensor diagnostics in
field
Reasonableness checks
Differential Rate Test
Calibration with gas
standards by laboratory
Independent
performance checks
with blind audit sample
Meter zero check
Independent
performance check of
temperature readings
When
Performed/Frequency
Beginning and end of test
Throughout test
Beginning and end of test
Prior to analysis of each
lot of samples submitted
Twice during previous
year
Prior to testing
Beginning of test period
Expected or Allowable
Result
Voltage and current checks
within ± 1% reading
Readings should be around
1 80 to 200 kW net power
output at full load
± 10% of expected differential
pressure
± 1 .0% for each gas
constituent
± 3.0% for each major gas
constituent (methane, CO2)
Reported flow rate
<0.1GPM
Difference in temperature
readings should be < 1.5 °F
Results Achieved
± 0.2% voltage
± 0.9% current
Readings were 193 kW
Results satisfactory
Results satisfactory, see
Section 3.2.2.4
0.03 GPM recorded
Temperature readings
within 0.8 °F of reference.
3.2.2. Electrical Efficiency
The DQO for electrical efficiency was to achieve an uncertainty of ± 1.6 percent or less at full load.
Recall from Equation 1 (Section 1.4.1) that the electrical efficiency determination consists of three direct
measurements: power output, fuel flow rate, and fuel LHV. The accuracy goals specified to meet the
electrical efficiency DQO consisted of ± 1.0 percent for power output, ±1.0 percent for fuel flow rate,
and ± 0.2 percent for LHV. The achieved accuracies for each measurement are compounded to determine
overall accuracy of the reported efficiency. The methodology for compounding errors of multiple
measurements (i.e., the square root of the sum of the squares) is detailed in the TQAP and not repeated
here. The following sections summarize actual errors achieved in the contributing measurements and the
overall compounded error.
Power Output: As discussed in Section 3.2.1, factory calibrations of the 7500 ION with a NIST-
traceable standard and the inherent error in the current and potential transformers resulted in ± 1.0-percent
error in power measurements. Reasonableness checks in the field verified that the meter was functioning
properly. The average power output at full load was measured to be 193 kW and the measurement error
is determined to be ± 1.9 kW.
Heat Input: The DQI goal for fuel flow rate was reconciled through calibration of the gas meter and the
gas temperature and pressure sensors used to correct measured gas volumes to standard conditions. All
three components were calibrated with NIST-traceable standards. As shown in Table 3-2, the individual
instruments errors were 0.5, 0.5, and 0.2 percent for flow, pressure, and temperature respectively. The
overall error in ADG flow rate then is 0.7 percent of reading. Therefore, the average flow rate at full load
was 53.0 scfm with a measurement error of ± 0.39 scfm. Complete documentation of data quality results
for fuel flow rate is provided in Section 3.2.2.3.
3-6
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Uncertainty in the ADG LHV results was 3 percent (Section 3.2.2.4). The average LHV during testing
was 552 Btu/scf and the measurement error corresponding to this heating value is ± 16 Btu/scf. The heat
input compounded error then is ± 53.0 103Btu/hr, or 3.1 percent relative error at the average measured
heat input of 1,766 103Btu/hr.
The errors in the divided values compound similarly for the electrical efficiency determination. The
electrical power measurement error is ± 1.0 percent relative (Table 3-2) and the heat input error is ± 3.1
percent relative. Therefore, compounded relative error for the electrical efficiency determination at full
load is 36.8 ±1.2 percent, or a relative compounded error of 3.3 percent. This level of uncertainty
exceeds the DQO for this parameter, primarily due to the conservative estimate of uncertainty in the LHV
determination.
3.2.2.1. PTC-50 Requirements for Electrical Efficiency Determination
PTC-50 guidelines state that efficiency determinations were to be performed within 60 minute test periods
in which maximum variability in key operational parameters did not exceed specified levels. Table 3-4
summarizes the maximum permissible variations observed in power output, ambient temperature, ambient
pressure, ADG pressure at the meter, and ADG temperature at the meter for each test run. The table
shows that the PTC-50 requirements for all parameters other than ADG flow rate were met for all test
runs. Several of the ADG flow rate variabilities exceeded the ± 2% criterion. PC25C operations were
very stable during testing as indicated by the low variability in power output and fuel heat content, so
these variabilities are believed to be caused by the low resolution of the gas meter transmitter signal. In
any case, the variability in this measurement is not expected to impact the 60 minute average values, or
the subsequent the efficiency determinations.
Table 3-4. Variability in Operating Conditions
Maximum Allowable
Variation
Runl
Run 2
Run 3
Run 4
Run 5
Run 6
Run?
Run8
Run 9
Maximum Observed Variation" in Measured Parameters
Power
Output (kW)
±2%
0.04
0.02
0.04
0.06
0.07
0.04
0.03
0.05
0.05
Ambient
Temp. (°F)
±5°F
1.7
2.3
2.6
1.9
2.6
2.4
1.8
2.0
1.9
Ambient
Pressure
(psia)
±1%
0.07
0.07
0.06
0.06
0.07
0.11
0.11
0.08
0.11
ADG
Pressure
(psia)
±2%
0.51
0.52
0.53
0.29
0.26
0.28
0.22
0.23
0.31
ADG Flow
Rate (scfm)
±2%
2.0
1.9
2.6
2.2
2.6
2.3
3.2
2.5
4.0
a Maximum (Average of Test Run - Observed Value) / Average of Test Run • 1 00
3.2.2.2. Ambient Measurements
Ambient temperature, relative humidity, and barometric pressure at the site were monitored throughout
the extended verification period and the controlled tests. The instrumentation used is identified in Table
3-2 along with instrument ranges, data quality goals, and data quality achieved. All three sensors were
factory-calibrated using reference materials traceable to NIST standards. The pressure sensor was
3-7
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calibrated prior to the verification testing, confirming the ±0.1 percent accuracy. The temperature and
relative humidity sensors were also calibrate within a year prior to testing which verified that the ± 0.2 °F
accuracy goal for temperature and ± 2 percent accuracy goal for relative humidity were met.
3.2.2.3. Fuel Flow Rate
The Dresser-Roots Model 5M175 rotary displacement gas meter was factory-calibrated in April 2003
prior to installation at the Red Hook site. Calibration records were obtained and reviewed to ensure that
the ± 1.0-percent instrument accuracy goal was satisfied. Roots meter calibrations are permanent,
indicating that this meter's accuracy is ± 0.5 percent.
Following manufacturer guidelines, a differential rate test was conducted on the meter in the field. The
differential pressure across the meter was measured using a manometer while operating the PC25C on
ADG. Two flow rates were checked and the measured differential pressure agreed with the meter
performance curves at both points.
Finally, an ADG calibration curve was developed in the field to account for bias introduced by the pulse
counter signal transmitter and data acquisition system (DAS). A 4-point calibration was conducted where
manual meter index readings were compared to electronic ADG flow rate data logged by the DAS. The
data were used to develop a linear equation which was applied to the average ADG flow rates logged
during the controlled test periods. The correlation coefficient of the 4 point calibration curve was 0.9996.
3.2.2.4. Fuel Lower Heating Value
Full documentation of ADG sample collection date, time, run number, and canister ID was recorded and
laboratory chain of custody forms were shipped along 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 Analytical Laboratories of Brighton, CO, for compositional analysis and determination
of LHV per ASTM test Methods D1945 and D3588, respectively. The DQI goals were to measure
methane concentrations within ±3.0 percent of a NIST-traceable blind audit sample and to achieve less
than ± 0.2 percent difference in LHV duplicate analyses results. Blind audits were submitted to Empact
on two similar verifications within the past year to evaluate analytical accuracy on the methane analyses
[13, 14]. Both audits indicated analytical accuracy within 0.5 percent for the methane determination, and
LHV repeatability of within ± 0.2 percent. Since the same sampling and analytical procedures were used
here by the same analyst, the audit was not repeated a third time. As such, a uncertainty in the LHV
determination of ± 3.0 percent is assigned.
In addition to the blind audit samples, duplicate analyses were conducted on three of the 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 0.05 percent for methane and 0.05
percent for LHV.
3.2.3. Heat Production and Thermal Efficiency
Several measurements were conducted to determine heat production and thermal efficiency. These
measurements include water flow rate, water supply and return temperatures, and heat input. The
individual errors in each of the measurements are then propagated to determine the overall error in heat-
recovery rate and efficiency. The Controlotron ultrasonic heat meter was used to continuously monitor
water flow rate for the cooling module loop. This meter has a NIST-traceable factory-calibrated accuracy
of ± 1.0 percent of reading. A zero check was also performed on the meter. The meter readings were
0.03 GPM or less with the circulation loop shut down.
3-8
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The two temperature sensors used to measure delta T were calibrated against a reference thermocouple
with NIST-traceable accuracy. This resulted in a single point estimate of bias in the delta T determination
of 0.8 °C. This absolute error equates to an error of 1.6 percent relative to the average delta T measured
during the full load testing (about 49 °C). The overall error in heat recovery and removal rate is then the
combined error in flow rate and temperature differential. The heat recovery and removal rate
determination, therefore, has a relative compounded error of ± 1.9 percent. The absolute error in the
average heat recovery and removal rate at full power (994 x 103Btu/hr) then is ± 18.9 x 103Btu/hr.
Average thermal efficiency at full load is the compounded error in heat-recovery rate and the heat input
error (3.1 percent), or 56.9 ±2.1 percent, or a relative compounded error of 3.7 percent. This level of
uncertainty exceeds the DQO for this parameter, again primarily due to the conservative estimate of
uncertainty in the LHV determination.
3.2.4. Total Efficiency
Total efficiency is the sum of the electrical power and thermal efficiencies. For this test, total efficiency
at full load is calculated as 36.8 ±1.2 percent (± 3.3-percent relative error) plus 56.9 ±2.1 percent (± 3.7-
percent relative error). This is based on the determined errors in electrical and thermal efficiency at the
full power setting. The total potential CHP efficiency at full load is then 93.8 ± 2.4 percent, or 2.5
percent relative error. This compounded relative slightly exceeds the data quality objective for this
parameter.
3.2.5. Exhaust Stack Emission Measurements
EPA reference method requirements form the basis for the DQIs specified in the TQAP and listed in
Tables 3-1 and 3-2. Each method specifies sampling and calibration procedures and data quality checks.
These specifications, when properly implemented, ensure the collection of high quality and representative
emissions data. The specific sampling and calibration procedures vary by method and class of pollutants,
and are summarized in Table 3-5. The table lists the method quality requirements, the acceptable criteria,
and the results for the test conducted here. It is generally accepted that conformance to the reference
method quality requirements demonstrates that the qualitative DQIs have been met.
All of the emissions testing and reference method quality control procedures were conducted by the
emissions testing contractor either in the field during testing or in their calibration and analytical
laboratories. All of the field sampling procedures and calibrations were closely monitored by GHG
Center personnel. In addition, documentation of all sampling and analytical procedures, data collection,
and calibrations have been procured, reviewed, and filed by the GHG Center. Table 3-5 is followed by a
brief explanation of the QA/QC procedures implemented for each class of pollutant quantified during this
verification.
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Table 3-5. Summary of Emissions Testing Calibrations and QC Checks
Measurement
Variable
NOX
NOX, CO, THC,
CO2, and O2
concentrations
CH4 concentrations
Exhaust gas
volumetric flow rate
Calibration/QC Check
NO2 to NO converter
efficiency test
Analysis of audit gas
Analyzer calibration error
test
System bias checks
Calibration drift test
Triplicate injections
Calibration of GC with
gas standards by certified
laboratory
Pilot tube dimensional
calibration / inspection
Thermocouple calibration
When
Performed/ Frequency
Once before testing
Daily before testing
Before each test run
After each test run
Each test run
Immediately prior to
sample analyses and/or
at least once per day
Once before and once
after testing
Once after testing
Expected or
Allowable Result
Efficiency > 90%
± 5% of reading
± 2% of analyzer span
± 5% of analyzer span
± 3% of analyzer span
± 5% difference
± 5% for
each compound
See 40CFR60 Method
2, Section 10.0
± 1.5% of average
stack temperature
Result of Calibration(s)
or Check(s)
Efficiency 99.8%
± 4% of reading
All within allowable level
for each day
All within allowable level
for each test run
All within allowable level
for each test run
All within allowable level
for each day
Calibration criteria met
Within 0.3% of reference
TC
3.2.5.1. NOX, CO, THC, CO2, and O2 Concentrations
Test personnel performed sampling system calibration error tests prior to each test run. All calibrations
employed a suite of three EPA Protocol No. 1 calibration gases (four for CO) that spanned the instrument
ranges. Appropriate calibration ranges were selected for each pollutant based on exhaust gas screening
(ranges are summarized in Table 3-2). The daily analyzer calibration error goal for each instrument was ±
2.0 percent of span. It was met for each analyzer during each day of testing.
Sampling system bias was evaluated for each parameter at the beginning of each test run using the zero
and mid-level calibration gases. System response to the zero and mid-level calibration gases also
provided a measure of drift and bias at the end of each test run. The maximum allowable sampling
system bias and drift values were ± 5 and ± 3 percent of span, respectively. These specifications were
met for each parameter and for each test run.
Testers performed a NOX converter efficiency test as described in Section 3.5 of the TQAP. The
converter efficiency was 99.8 percent, which meets the 98-percent goal specified in the method. They
also followed EPA Method 205 field evaluation procedures which specifies that gas concentrations will
be within ± 2.0 percent of the predicted value after dilution.
As expected, NOX emissions were very low (1 ppm or less). To evaluate the NOX sampling system
accuracy at low concentrations, an EPA Protocol 1 calibration gas with a certified NOX concentration of
2.50 ppm in N2 was diluted 50:50 (using the Method 205 dilution system) with another Protocol 1
calibration gas of 17.9 % CO2 in N2. This audit gas allowed the Center to simultaneously evaluate NOX
sampling system accuracy and CO2 quenching bias. The resulting calibration gas mixture was 1.25 ppm
NOX and 8.95 % CO2. System response was 1.2 ppm for NOX and 9.0 % for CO2, both within the ± 5%
criteria.
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3.2.5.2. CH4 Concentrations
The TQAP specified EPA Method 18 for determining stack gas methane concentrations. Test operators
injected calibration gas standards into the GC to establish a concentration standard curve prior to sample
analysis. The operator repeated the injections until the average of all desired compounds from three
separate injections agreed to within 5.0 percent of the certified value. The acceptance criterion was met
for all runs.
The analysts injected the mid-range standard to quantify instrument drift at the completion of each test.
The analyst would repeat the calibration process used for the average of the two calibration curves to
determine concentrations if he observed a variance larger than 5.0 percent.
3.2.5.3. Exhaust Gas Volumetric Flow Rate
Reference Methods 1 through 4, used for determination of exhaust gas volumetric flow rate, include
numerous quality control/quality assurance procedures that are required to ensure collection of
representative data. The most important of these procedures are listed in Table 3-5 along with the results
for these tests. These methods do not specify overall uncertainties, but it is generally accepted that
conformance to the control/quality assurance procedures will result in an overall method uncertainty
ranging from around 5 to 20 percent [15].
3-11
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4.0
TECHNICAL AND PERFORMANCE DATA SUPPLIED BY UTC FUEL CELLS
Note: This section provides an opportunity for UTC Fuel Cells 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 statements made in this section.
UTC Fuel Cells PC25C has under gone emissions testing by independent organizations numerous times
in the past. Below is a summary of these previous test results:
Independently Reported Emissions Levels
Lb/MWhr, at 200 kW
Source
Rex Tech '
Airtech 2
TRC3
ETV5
NOx
0.019
0.064
0.019
0.013
CO
0.002
<0.002
<0.012
0.029
THC
0.020
0.019
<0.0114
0.78
CH4
0.020
0.018
0.003
0.80
NMHC
0.007
<0.008
CO2
1295
1437
1. Test Report of Emissions from a PC25C Fuel Cell at the Connecticut Juvenile Training School.
Middletown. CT
Rex Technical Services, LLC, C-ll-05, CJTS Report Addendum, October, 2002
2. Report on Natural Gas Fuel Emission Testing. Conducted on the ONSIPC25C 200 kW Fuel Cell
for Concurrent Technologies Corporation. Johnstown. PA.
Airtech Environmental Services Inc., Report No. 1179-1, March 10, 2000
3. Waste Water Digester/Fuel Cell Power Plant Energy Recovery Demonstration: Yonkers Joint
Waste Water Treatment Plant
TRC Environmental Corporation, Project No. 22817, October, 1998
4. THC not measured; sum of CH4 + NMHC shown in this table for comparison.
5. This report
These sets of tests indicate much higher levels of THC and CH4 reported by ETV than in previous
testing. UTC Fuel Cells recognizes the level of difficulty in measuring and accounting for background
levels of these constituents; oftentimes the ambient environment contains higher levels than that in the
power plant exhaust. Indeed the PC25C at the Red Hook facility is located indoors in a room with other
industrial equipment, and SRI has recognized this site installation can impact the results.
In addition to the above, the published UTC Fuel Cells PC25C Design and Application Guide tabulates
emissions as part of the overall power plant specification. In this spec, combined emissions for NOx +
CO + SOx + NMHC + Particulates is 0.04 Ib/MWhr and CO2 emissions is 1164 Ib/MWhr.
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5.0 REFERENCES
[1] Southern Research Institute, Test and Quality Assurance Plan - Electric Power and Heat
Production 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.
[2] American Society of Mechanical Engineers, Performance Test Code for Fuel Cell Power
Systems, ASMEPTC-50, New York, NY. 2002.
[3] American National Standards Institute / American Society of Heating, Refrigeration, and Air-
conditioning Engineers, Method of Testing Thermal Energy Meters for Liquid Streams in HVAC
Systems, ANSI/ASHRAE 125-1992, Atlanta, GA. 1995.
[4] American Society for Testing and Materials, Standard Test Method for Analysis of Natural Gas
by Gas Chromatography, ASTM D1945-98, West Conshohocken, PA. 2001.
[5] 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.
[6] Southern Research Institute, Environmental Technology Verification Report: UTC Fuel Cells
PC25C Power Plant - Gas Processing Unit Performance for Anaerobic Digester Gas,
SRI/USEPA-GHG-QAP-26B, www.sri-rtp.com. Greenhouse Gas Technology Center, Southern
Research Institute, Research Triangle Park, NC. September 2004.
[7] American National Standards Institute, ANSI / Institute of Electrical and Electronics Engineers,
IEEE, Master Test Guide for Electrical Measurements in Power Circuits, ANSI/IEEE Std. 120-
1989, New York, NY. October. 1989.
[8] American National Standards Institute, ANSI / Institute of Electrical and Electronics Engineers,
IEEE, Recommended Practices and Requirements for Harmonic Control in Electrical Power
Systems, IEEE Std. 519-1992, New York, NY. April. 1993.
[9] American National Standards Institute, ANSI / Institute of Electrical and Electronics Engineers,
National Standards for Electric Power Systems and Equipment - Voltage Ratings (Hertz), ANSI
C84.1-1995. American National Standards Institute, National Electrical Manufacturers
Association, Rosslyn, VA. 1996.
[10] U.S. Environmental Protection Agency, Code of Federal Regulations, Title 40, Part 60, New
Source Performance Standards, Appendix A, U.S. EPA, Washington, DC, 1999.
[11] U.S. Environmental Protection Agency, Compilation of Air Pollutant Emission Factors AP-42,
Fifth Edition, Volume I (4th Edition), U.S. EPA, Research Triangle Park, NC, 1995.
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[12] Southern Research Institute, Environmental Technology Verification Report: Electric Power
Generation Using a Phosphoric Acid Fuel Cell on a Municipal Solid Waste Landfill Gas Stream,
SRI/USEPA-GHG-VR-01, www.sri-rtp.com. Greenhouse Gas Technology Center, Southern
Research Institute, Research Triangle Park, NC. August 1998.
[13] Southern Research Institute, Environmental Technology Verification Report: Combined Heat
and Power at a Commercial Supermarket - Capstone 60 kW Microturbine CHP System,
SRI/USEPA-GHG-VR-27, www.sri-rtp.com. Greenhouse Gas Technology Center, Southern
Research Institute, Research Triangle Park, NC. September 2003.
[14] Southern Research Institute, Environmental Technology Verification Report: Residential Electric
Power Generation Using the Plug Power SU1 Fuel Cell System, SRI/USEPA-GHG-VR-25,
www.sri-rtp.com. Greenhouse Gas Technology Center, Southern Research Institute, Research
Triangle Park, NC. September 2003.
[15] Shigehara, R.T., Measurement Uncertainty of Selected EPA Test Methods, Emission Monitoring,
Inc., Presented at Stationary Source Sampling and Analysis for Air Pollutants XXV Conference,
March 2001.
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