SRI/USEPA-GHG-VR-45 vl.6
May 2012
THE ENVIRONMENTAL TECHNOLOGY VERIFICATION PROGRAM
ET/
NY5ERDA
SOUTHERN RESEARCH
Legendary Discoveries. Leading Innovation.
ETV Joint Verification Statement
TECHNOLOGY TYPE: Electric Power and Heat Production using Natural Gas
APPLICATION: Combined Heat and Power System
TECHNOLOGY NAME: Tecogen Model CM-100
COMPANY: Tecogen
ADDRESS' 45 First Avenue
Waltham, MA 02451
WEB ADDRESS: http://www.tecogen.com/
The U.S. Environmental Protection Agency's Office of Research and Development (EPA-ORD) operates
the Environmental Technology Verification (ETV) program to facilitate the deployment of innovative
technologies through performance verification and information dissemination. The goal of ETV is to
further environmental protection by accelerating the acceptance and use of improved and innovative
environmental technologies. ETV seeks to achieve this goal by providing high-quality, peer-reviewed
data on technology performance to those involved in the purchase, design, distribution, financing,
permitting, and use of environmental technologies.
ETV works in partnership with recognized standards and testing organizations, stakeholder groups that
consist of buyers, vendor organizations, and permitters, and with the full participation of individual
technology developers. The program evaluates the performance of technologies by developing test plans
that are responsive to the needs of stakeholders, conducting field or laboratory tests, collecting and
analyzing data, and preparing peer-reviewed reports. All evaluations are conducted in accordance with
rigorous quality assurance protocols to ensure that data of known and adequate quality are generated and
that the results are defensible.
The Greenhouse Gas Technology Center (GHG Center), operated by Southern Research Institute
(Southern), is one of six verification organizations operating under the ETV program. A technology area
of interest to some GHG Center stakeholders is distributed electrical power generation (DG), particularly
with combined heat and power (CHP) capabilities.
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The GHG Center collaborated with the New York State Energy Research and Development Authority
(NYSERDA) to evaluate the performance of an array of six Tecogen Model CM-100 units - combined
heat and power (CHP) system manufactured by Tecogen and fueled with natural gas. The system is
owned and operated by BOCES in Verona, New York.
TECHNOLOGY DESCRIPTION
The following information has been supplied by the vendor and has not been verified. Building Energy
Solutions (BES) has installed six natural gas-fired Tecogen Model CM-100 Premium Power CHP
modules as part of a DG / CHP upgrade at the Madison-Oneida Board of Cooperative Educational
Services (BOCES) campus located in Verona, NY. The technical basis for the technology is as follows.
The Tecogen system utilizes natural gas fuel, combusted in an internal combustion engine, which is used
to drive an electric generator. Thermal energy in the engine's exhaust heat and other heat sources is
recovered and used for various purposes. The CHP array operates in response to the site's electrical
demand; power is not exported to the grid. Management of the host facility's peak electrical demand is a
fundamental economic driver for the system.
The installation recovers thermal energy from the 1C engine jacket coolant, oil cooler, and exhaust. The
recovered energy is designed to supply up to 4.4 million British thermal units per hour (MMBtu/h) from
the array of six units to the following district heating and cooling applications:
• year-round domestic hot water (DHW)
• heat supply to two 100-ton absorption chillers for air-conditioning during warm weather
• hydronic space heating during cold weather
The facility also incorporates two 7500-gallon insulated thermal storage tanks. Their function is to
provide approximately 2.5 MMBtu carry-through capacity for space heating and DHW needs during cold
weather periods when electrical demand is low.
The CHP heating and cooling applications displace fuel consumption by five existing natural gas-fired
boilers rated atl.94 MMBtu/h each. Two of the boilers are located adjacent to the CHP installation while
the remaining three are located elsewhere on the campus. Hydronic heating, DHW, and chilled water
piping is generally located in the ceiling spaces and corridors which connect the various building sections.
The electrical generators, panel boards, circulation pumps, and most other parasitic loads are connected to
the main service bus located in the building "Section H" mechanical room.
VERIFICATION DESCRIPTION
Rationale for the experimental design, determination of verification parameters, detailed testing
procedures, test log forms, and QA/QC procedures can be found in the draft ETV Generic Verification
Protocol (GVP) [3] for DG/CHP verifications developed by the GHG Center. Site specific information
and details regarding instrumentation, procedures, and measurements specific to this verification were
detailed in the Test and Quality Assurance Plan titled Test and Quality Assurance Plan - Building Energy
Soulutions, LLC Tecogen DG / CHP Installation. Both can be downloaded from the ETV Program web-
site (www. epa.gov/etv).
Controlled Testing
Controlled testing for the field testing was conducted on September 9, 2009 through September 11th,
2009. The defined system under test (SUT) was tested to determine performance for the following
verification parameters:
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• Electrical Performance
• Electrical Efficiency
• CHP Thermal Performance
• CHP Thermal Efficiency
• Atmospheric Emissions (controlled test period only).
• NOX and CO2 emissions reductions (offsets) relative to baseline conditions
Electrical and thermal performance and efficiency were quantified following the rationale and approaches
detailed in the GVP. Specifically, electrical generation efficiency can also be termed the "fuel-to-
electricity conversion efficiency." It is the net amount of energy a system produces as electricity
compared to the amount of energy input to the system in the fuel. Heat rate expresses electrical generation
efficiency in terms of British thermal units per kW-hour (Btu/kWh). For determination of thermal
performance, applicable CHP devices use a circulating liquid heat transfer fluid for heating or chilling.
The CHP equipment itself is considered to be within the SUT boundary. The balance of plant (BoP)
equipment, which employs the heating or chilling effect, is outside the system boundary. The GVP does
not consider how efficiently the BoP uses the heating or chilling effect. Actual thermal performance is the
heat transferred out of the SUT boundary to the BoP for both CHP heaters and chillers. Actual thermal
efficiency in heating service is the ratio of the thermal performance to total heat input in the fuel. Detailed
definitions and equations appear in Appendix C of the GVP.
The verification included a series of controlled test periods on September 10, 2009 in which the GHG
Center maintained steady system operations for three test periods at loads of 100%, 75%, and 50% of
capacity (100, 75, and 50 kW, respectively) on one of the six Tecogen CM 100 units. Equipment tag
name, Cogen 4 was selected from the six units to evaluate electrical and CHP efficiency and emissions
performance. Testing took place at night so it would not interfere with normal operations of the facility.
Five of the six units were shutdown during the controlled test period and temporary installation of
independent electrical power analyzers were placed on the Cogen 4 output bus. The analyzers recorded
the electrical performance parameters at 1-minute intervals. Water serves as the CHP heat transfer fluid.
Southern installed supply and return temperature sensors and an ultrasonic fluid flow meter to determine
heat recovery from the CHP system heat recovery loop.
Emissions data were recorded from the Cogen 4 exhaust stack on the roof of the mechanical room.
Southern's Horiba OBS-2200 PEMS (Portable Emissions Monitoring System) was installed on the
exhaust stack to measure atmospheric emissions including THC, CO, CO2, and NOX. Other parameters
including exhaust flow, exhaust temperature, exhaust pressure, moisture, ambient temperature, and
ambient pressure were also collected from the OBS-2200 to allow for computing exhaust gas flow at dry,
standard conditions. Fuel gas consumption was determined by a data logger connected to a revenue-grade
gas meter. Southern installed a Dresser brand Roots meter (model 11M175) in the CHP array gas line.
The meter incorporates a high-frequency pulse output for flow rate determinations. Test personnel
connected the meter output to the data logger and recorded the gas flow rate at least once per minute
during all test periods. Testing personnel also temporarily installed ports for collecting natural gas
samples for lower heating value (LHV) analysis.
Long-term Monitoring
The controlled tests were followed by a 1 year period of continuous monitoring to determine heat
recovery and power output, electrical and thermal efficiency, and estimated annual emission reductions
on the full array of six CHP units under normal operation.
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Quality Assurance
Quality assurance (QA) oversight of the verification testing was provided following specifications in the
ETV Quality Management Plan (QMP). On September 10th 2009, the EPA conducted a Technical
Systems Audit on site. Bob Wright from EPA and David Gratson from Neptune and Company, Inc
conducted the audit while controlled testing was underway. The GHG Center's QA manager conducted
an audit of data quality on 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, the project manager,
and the QA manager.
VERIFICATION OF PERFORMANCE
Electrical and Thermal Performance - Controlled Test Period
Gross and net electrical performance and efficiency as measured during the controlled test period are
presented in Table 1. Net electrical performance is exclusive of power consumed by CHP system
electrical loads required for system operation (parasitic loads). Parasitic loads are disproportionally high
during the controlled test period when only one unit is operating as compared to normal operations when
up to six cogeneration units may be operating. Parasitic loads during the controlled test period averaged
about 7 percent of gross power output, whereas during the long term monitoring, parasitic loads averaged
only 2-4 percent of gross power output (depending on load conditions). Uncertainties given in table 1
were determined by measurement error propagation as detailed in Section 7 of the GVP.
Thermal performance as measured during the controlled test period is not reported. The thermal
performance measurements are not considered representative for several reasons. The heat recovery fluid
flow measurement is not considered reliable because the flow velocities with only a single unit operating
were at or below the velocity at which the instrument accuracy rapidly deteriorates. Heat losses with only
a single unit operating are disproportionately high compared to normal operations with up to six units
operating. System controls, which seek to maintain the return temperature to the cogeneration array at a
constant level, did not appear to be able to operate as intended with only a single unit operating, resulting
in cycling of flow rate and return temperature. A detailed assessment of these factors is provided in
section 3.2.3 of the full verification report.
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May 2012
Table 1. Controlled Test Electrical and Thermal Performance
Test ID
100
kW
75
kW
50
kW
Runl
Run 2
Run3
Avg.
+/-
Runl
Run 2
Run 3
Avg.
+/-
Runl
Run 2
Run3
Avg.
+/-
Heat Input
(MMBtu/h)
1.18
1.17
1.17
1.18
1.8%
0.85
0.85
0.86
0.86
1.8%
0.57
0.57
0.58
0.58
1.8%
Electrical Power Generation Performance
Net Power
Generated
(kW)
91.8
91.2
91.4
91.5
0.7%
66.2
66.1
66.5
66.3
0.7%
41.6
41.4
42.8
41.9
0.7%
Net
Electrical
Efficiency
(%)
26.5
26.6
26.6
26.6
3.0%
26.5
26.4
26.4
26.4
3.0%
24.7
24.6
25.2
24.8
3.0%
Gross
Power
Generated
(kW)
98.0
97.3
97.7
97.7
0.7%
72.3
72.3
72.6
72.4
0.7%
47.3
47.2
47.5
47.3
0.7%
Gross
Electrical
Efficiency
(%)
28.3
28.4
28.4
28.4
3.0%
28.9
28.9
28.8
28.9
3.0%
28.1
28.0
28.0
28.0
3.0%
Reported uncertainties by measurement error propagation per GVP in percentage
of reported value. Net electrical performance is exclusive of electrical loads
required for system operation (parasitic loads). Parasitic loads are
disproportionately high during the controlled test conditions as described above.
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Emissions Performance - Controlled Test Period
Table 2 summarizes emissions performance of the Cogen 4 unit during the controlled test period.
THC and NOX emissions at the 50kW load condition are elevated. This is due to poor engine
performance at partial load - an abnormal operating condition. In normal operations, the units are run at
greater than 60 percent load and individual units are taken on and off line in response to facility electrical
demand.
Uncertainties given in this table were determined by calculating a 95 percent confidence interval over the
mean of all three runs at each load condition. The higher uncertainty for CO emissions at the 75kW load
conditions is due to a greater degree of fluctuation in CO concentration at the lower load conditions. CO
emissions measurements for the 50kW load condition were invalidated and are not reported. The
analyzer failed the span drift check at the conclusion of the test run, and examination of the data showed
that negative values were frequently reported.
Power Quality Performance - Controlled Test Period
Power quality was not monitored during the controlled test period due to a malfunction of data logging
equipment. This is not considered to have a significant impact on the quality of the performance
verification as power quality is proven to be sufficient for grid interconnect.
Electrical and Thermal Performance - Long Term Monitoring Period
Measurements necessary to determine electrical and thermal performance and efficiency were collected
over a period from September 2009 through September 2010. Table 3 provides a summary of the results.
During normal operations at the BOCES facility, the cogeneration array operates in response to electrical
demand. As such, the array typically operates at nearly full load during weekdays, with partial load at
nights and on weekends. Full load conditions are characterized by power generation rates over 300kW,
and night/weekend conditions are characterized by generation rates less than 300 kW. The cogeneration
array operated nearly continuously throughout the year of monitoring, with only one brief period of down
time (43 hours) in late June 2010.
Gross electrical efficiency during the extended test was 24.1 percent on an annual basis, 26.4 percent at
full load conditions, and 22 percent at partial load conditions. Parasitic loads accounted for 2 to 4 percent
of power production depending on load conditions.
As can be seen in Table 3, the electrical and thermal efficiency of the system is somewhat lower at partial
load than at full load. The lower thermal efficiency at partial load may be due to system heat losses -
which amount to a greater proportion of the total heat recovered at partial load than at full load.
The lower electrical efficiency at partial load is not fully explained by the data. However, at the very
lowest loads (occurring during weekend daytimes), fuel consumption was consistently observed to
increase as power output decreased. This could be due to the cogeneration array running in an inefficient
operating range at the lowest load conditions. During the controlled tests with only one of six units
operating, electrical efficiency decreased slightly at the 50 percent load condition, but not as much as was
observed during extended monitoring of the full cogeneration array.
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Table 2. Tecogen Emissions During Controlled Test Periods
Test ID
lOOkW
75 kW
50 kW
Runl
Run 2
Run3
Avg.
95% CI
Runl
Run 2
Run3
Avg.
95% CI
Runl
Run 2
RunS
Avg.
95% CI
Test ID
lOOkW
75 kW
50 kW
Runl
Run 2
RunS
Avg.
95% CI
Runl
Run 2
RunS
Avg.
95% CI
Runl
Run 2
RunS
Avg.
95% CI
Gross
Power
(kW)
98
97
98
98
72
72
73
72
47
47
48
47
Gross
Power
(kW)
98
97
98
98
72
72
73
72
47
47
48
47
CO Emissions
ppm
175
162
168
168
1.7%
44
81
96
74
5.3%
not reported*
not reported*
not reported*
Ib/hr
0.17
0.16
0.16
0.17
0.04
0.08
0.09
0.07
0.06
0.08
0.09
0.08
Ib/MWh
1.8
1.6
1.7
1.7
0.5
1.1
1.2
0.9
1.4
1.7
1.8
1.6
THC Emissions
ppm
5.7
4.8
4.9
5.1
1.2%
8.8
8.5
8.7
5.8
2.3%
273
288
292
284
1.5%
Ib/hr
0.006
0.005
0.005
0.005
0.008
0.008
0.008
0.008
0.154
0.185
0.201
0.180
Ib/MWh
0.06
0.05
0.05
0.05
0.11
0.11
0.11
0.11
3.2
3.9
4.2
3.8
CO2 Emissions
Volume %
9.3
9.2
9.2
9.2
0.02%
9.1
9.1
9.1
9.1
0.06%
9.2
9.2
9.2
9.2
0.07%
Ib/hr
91
90
91
91
80
85
86
84
52
59
63
58
Ib/MWh
930
927
928
928
1113
1182
1180
1158
1095
1250
1328
1224
NOx Emissions
ppm
12.8
12.9
13.1
12.9
2.5%
8.4
8.3
7.8
5.6
4.0%
843
881
881
869
1.6%
Ib/hr
0.013
0.013
0.013
0.013
0.007
0.008
0.007
0.008
0.475
0.567
0.608
0.550
Ib/MWh
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
10.0
12.0
12.8
11.6
*Carbon monoxide results for the 50 percent load condition are not reported because the instrument failed the span drift check
at the conclusion of the testing at this condition and the results appeared suspect upon examination (concentrations during the
run were frequently recorded as negative values).
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Table 3. Extended Test Results Summary
Annual
Average
Full Load -
(Weekday)
(>=300kW)
Partial
Load-
(Night)
(<300kW)
Average
Net
Power
Output
(kW)
293
394
211
+/-
0.7%
0.7%
0.7%
Average
Heat
Recovery
(MMBtu/hr)
2.26
2.98
1.68
+/-
4.4%
4.4%
4.4%
Average
Thermal
Efficiency
(%)
53.7
60.4
48.2
+/-
4.9%
4.9%
4.9%
Average
Net
Electrical
Efficiency
(%)
23.5
25.8
21.3
+/-
3.0%
3.0%
3.0%
Average
Total
Efficiency
(%)
77.2
86.2
69.5
+/-
3.5%
3.5%
3.5%
Reported uncertainties by measurement error propagation per GVP.
Signed by Cynthia Sonich-Mullin
(3/7/2013)
Cynthia Sonich-Mullin
Director
National Risk Management Research Laboratory
Office of Research and Development
Signed by Tim Hansen
(1/3/2013)
Tim Hansen
Director
Greenhouse Gas Technology Center
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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