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AEPA COMBINED HEAT AND
POWER PARTNERSHIP ^ pro^°
Fuel and Carbon Dioxide Emissions Savings Calculation
Methodology for Combined Heat and Power Systems
U.S. Environmental Protection Agency
Combined Heat and Power Partnership
June 2021
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The U.S. Environmental Protection Agency (EPA) CHP Partnership is a voluntary program that
seeks to reduce the environmental impact of power generation by promoting the use of CHP. The
CHP Partnership works closely with energy users, the CHP industry, state and local governments,
and other stakeholders to support the development of new CHP projects and promote their energy,
environmental, and economic benefits.
The CHP Partnership provides resources about CHP technologies, incentives, emissions profiles,
and other information on its website at www.epa.gov/chp. For more information, contact the CHP
Partnership Helpline at chpffiepa.gov or (703) 373-8108.
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TABLE OF CONTENTS
1.0 Introduction 1
2.0 What IsCHP? 3
2.1 How CHP Systems Save Fuel and Reduce C02 Emissions 4
3.0 Calculating Fuel and C02 Emissions Savings from CHP 6
3.1 Fuel Use and C02 Emissions from Displaced On-site Thermal Productionand Displaced Grid Electricity 8
3.1.1 Fuel Use and CO2 Emissions from Displaced On-site Thermal Production 8
3.1.2 Fuel Use and CO2 Emissions from Displaced Grid Electricity 10
3.2 Fuel Use and C02 Emissions of the CHP System 12
Appendix A CEESC Example Calculation 15
A.l Calculator Inputs 15
A.2 Calculator Results 20
Appendix B Estimating Displaced Grid Electricity Fuel Use and C02 Emissions 25
B.l Load Duration Curves and Grid Dispatch Order 26
B.2 Methods for Estimating Displaced Grid Emissions 28
B.3 EPA's AVoided Emissions and geneRation Tool (AVERT) 30
B.4 EPA's Emissions & Generation Resource Integrated Database (eGRID) 34
B.5 Recommendations 42
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1.0 INTRODUCTION
The appropriate quantification of energy and emissions
savings from combined heat and power (CHP) plays a
critical role in defining the value proposition of CHP for
policy makers, project developers, end users, and other
industry stakeholders. This paper provides the EPA
Combined Heat and Power Partnership's (the Partnership)
recommended methodology for calculating fuel and
carbon dioxide (CO2) emissions savings from CHP
compared to conventional separate heat and power
(SHP).1 This methodology recognizes the multiple outputs
of CHP systems and compares the fuel use and emissions
of the CHP system to the fuel use and emissions that
would have occurred with separate heat and power (SHP).
The methodology recommended in this paper is not
intended as a substitute methodology for organizations
quantifying and reporting GHG inventories. EPA
recommends that organizations use accepted GHG
protocols, such as the World Resources Institute's
Greenhouse Gas Protocol 2 or The Climate Registry's
General Reporting Protocol 3 , when calculating and
reporting a company's carbon footprint.
However, the CO2 emissions savings amounts estimated
using the methodology recommended in this paper can be
reported as supplemental information in an organization's
public disclosure of its GHG inventory to help inform
stakeholders of the emissions benefits of CHP and to
highlight the organization's commitment to energy-
efficient and climate-friendly technologies.
The paper is organized as follows:
• Section 2 introduces CHP and explains the basis for fuel and CO2 emissions savings from CHP compared
to SHP.
• Section 3 presents a methodology for calculating the fuel and CO2 emissions savings from CHP.
1The CEESC is available at: https://www.epa.gov/chp/chp-energy-and-emissions-savings-calculator. CHP can also reduce emissions of
other greenhouse gases, such as methane (CH4) and nitrous oxide (N20), along with criteria air pollutants. Although methane and nitrous
oxide are not discussed in this paper, they are accounted for in the CHP Energy and Emissions Savings Calculator (CEESC).
2 The Greenhouse Gas Protocol is available at: http://www.eheprotocol.ore/.
3 The Climate Registry General Reporting Protocol is available at: http://www.theclimatereeistrv.ore/resources/protocols/eeneral- reportine-
protocol/.
Summary of Key Points
• To calculate the fuel and C02 emissions savings
of a CHP system, it is necessary to account for
both electric and thermal outputs of the CHP
system.
• The CHP system's thermal output displaces the
fuel normally consumed by and emissions
emitted from on-site thermal generation in a
boiler or other equipment, and the power
output displaces the fuel consumed and
emissions from grid electricity.
• To quantify the fuel and C02 emissions savings of
a CHP system, the fuel use of and emissions
released from the CHP system are subtracted
from the fuel use and emissions that would
normally occur without the system (i.e., using
SHP).
• A key factor in estimating the fuel and CO2
emissions savings for CHP is determining the
heat rate and emissions factor of displaced grid
electricity. Two sets of grid emissions factors
are available from EPA. The choice of factors
depends on the system's location and
operating conditions. Appendix B provides
information about these inputs.
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• Appendix A presents a sample calculation of fuel and CO2 emissions savings using the EPA CHP Energy
and Emissions Savings Calculator (CEESC).
• Appendix B explains methods of estimating displaced grid electricity fuel use and C02 emissions
impacts using EPA's Emissions & Generation Resource Integrated Database (eGRID) and AVoided
Emissions and geneRation Tool (AVERT) as sources for two key variables in the calculation of fuel and
CO2 emissions savings from displaced grid electricity: displaced grid electricity heat rate [where the
heat rate is the ratio of fuel energy input (in Btu) as heat per unit of net power output (in kWh)] and
CO2 emissions factors. It also describes how to select values for these variables.
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2.0 WHAT IS CHP?
Combined heat and power (CHP) is a highly efficient method of providing power and useful thermal energy
(heating or cooling) at the point of use with a single fuel source. By employing waste heat recovery technology
to capture a significant portion of the heat created as a by-product of fuel use, CHP systems typically achieve
total system efficiencies of 65 to 80 percent. An industrial or commercial entity can use CHP to produce
electricity and thermal energy instead of obtaining electricity from the grid and producing thermal energy in an
on-site furnace or boiler. In this way, CHP can provide significant energy efficiency, cost savings, and
environmental benefits compared to the combination of grid-supplied electricity and on-site boiler use
(referred to as separate heat and power or SHP).
CHP plays important roles both in efficiently meeting U.S. energy needs and in reducing the environmental
impact of power generation. Currently, CHP systems represent approximately 7 percent of the electric
generating capacity in the United States.4 Benefits of CHP include:
• Efficiency benefits: CHP requires less fuel than SHP to produce a given energy output, and because
electricity is generated at the point of use, transmission and distribution losses that occur when
electricity travels over power lines from central power plants aredisplaced.
• Reliability benefits: CHP can be designed to provide high-quality electricity and thermal energy on site,
reducing reliance on the electric grid, decreasing the impact of outages, and improving power quality
for sensitive equipment.
• Environmental benefits: Because less fuel is burned to produce each unit of energy output, CHP
reduces emissions of greenhouse gases (GHG) and other air pollutants.
• Economic benefits: Because of its efficiency benefits, CHP can help facilities save money on energy.
Also, CHP can provide a hedge against fluctuations in electricity costs.
In the most common type of CHP system, known as a topping cycle (see Figure 1), fuel is used by a prime mover5
to drive a generator to produce electricity, and the otherwise-wasted heat from the prime mover is recovered
to provide useful thermal energy. Examples of the two most common topping cycle CHP configurations are:
• A reciprocating engine or gas turbine burns fuel to generate electricity and a heat recovery unit
captures heat from the exhaust and cooling system. The recovered heat is converted into useful thermal
energy, usually in the form of steam or hot water.
• A steam turbine uses high-pressure steam from a boiler to drive a generator producing electricity. Low-
pressure steam extracted from or exiting the steam turbine is used for industrial processes, space
heating or cooling, domestic hot water, or for otherpurposes.
4 U.S. Department of Energy, CHP Installation Database, 2020, available at https://doe.icfwebservices.com/chpdb/.
5 Prime movers are the devices (e.g., reciprocating engine, gas turbine, microturbine, steam turbine) that convert fuels to electrical energy via a
generator.
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Figure 1: Typical Reciprocating Engine/Gas Turbine CHP Configuration (Topping Cycle)
In another type of CHP system, known as a bottoming cycle, fuel is used for the purpose of providing thermal
energy in an industrial process, such as a furnace, and heat from the process that would otherwise be wasted
is used to generate power.
2.1 How CHP Systems Save Fuel and Reduce CO2 Emissions
CHP's efficiency benefits result in reduced primary energy6 use and thus lower CO2 emissions.
Figure 2 shows the efficiency advantage of CHP compared to SHP.7 CHP systems typically achieve total
efficiencies of 65 to 85 percent compared to about 50 to 55 percent for SHP. As shown in Figure 2, CHP systems
not only reduce the amount of total fuel required to provide electricity and thermal energy but also shift where
that fuel is used. Installing a CHP system on site will generally increase the amount of fuel that is used at the
site, because additional fuel is required to operate the CHP system compared to the equipment that otherwise
would have been used on site to produce needed thermal energy.
In the example shown in Figure 2, the on-site fuel use increases from 55 units in the SHP case to 100 units in
the CHP case. However, despite this increase in on-site fuel use, the total fuel used to provide the facility with
the required electrical and thermal energy drops from 155 units in the SHP case to 100 units in the CHP case, a
35 percent decrease in the amount of total fuel used.8 Using less fuel to provide the same amount of energy
can significantly reduce C02 and other emissions compared to separate heat and power. Applying U.S. average
fossil fuel emissions from eGRID, the total emissions for a 1 MW CHP engine operating at full load 8,000 hours
6 Primary energy is the fuel that is consumed to create heat and/or electricity.
7 Like Figure 1, Figure 2 illustrates the most common CHP configuration known as the topping cycle. See section 2.0 for more information.
8 Comparison made with a 1 MW CHP engine, assumed to have a 36% electric efficiency and 80% total CHP efficiency, typical for reciprocating
engines in this size range. Average efficiency for delivered grid electricity is assumed to be 36% (eGRID, see note below Figure 2), and on-site
boiler efficiency is assumed to be 80%.
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a year are estimated at 4,200 tons, compared to a total of 8,300 tons to deliver the same amount of electricity
and thermal energy with SHP.
Figure 2: Energy Efficiency and Emissions Savings - Topping Cycle CHP Versus Separate Heat and Power
(SHP) Production
Conventional Generation
Emissions
6.2 kTbns/yr
Power Station Fuel
(U.S. Fossil Fuel Mix)
>
155 Units Fuel
36% Efficient
Electricity
Boiler Fuel
(Gas)
Emissions
2.1 kTons/yr
Combined Heat and Power (CHP)
36 Units
Electricity
Annual
Consumption
44 Units
Heat
T~
I
I
Electricity
Combined Heat and CHP Fuel
Power (CHP) (Gas)
1 MW Natural Gas 100 Units Fuel
Reciprocating Engine
Emissions
4.2 kTons/yr
54% Efficient
OVERALL EFFICIENCY
80% Efficient
Note: Conventional power plant delivered efficiency of 36% (higher heating value [HHV']) is based on eGRID2019 and reflects the national
average all fossil generating efficiency of 38.2% and 4.88% transmission and distribution losses. Emissions estimates are based on
eGRID2019 fossil fuel average. eGRID provides information on emissions and fuel resource mix for individual power plants, generating
companies, states, and subregions of the power grid. eGRID is available at https://www.epa.eov/egrid.
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3.0 CALCULATING FUEL AND C02 EMISSIONS SAVINGS FROM CHP
To calculate the fuel or C02 emissions savings of a CHP system,
both outputs of the CHP system—thermal energy and electricity-
must be accounted for. The CHP system's thermal output typically
displaces the fuel otherwise consumed in an on-site boiler, and
the electric output displaces fuel consumed at central station
power plants.9 Moreover, the CHP system's electric output also
displaces fuel consumed to produce electricity lost during
transmission and distribution. Some CHP systems use absorption
chillers to convert thermal energy into chilled water for cooling
applications. This methodology document only covers traditional
CHP applications.
The displaced fuel use and C02 emissions associated with the
operation of a CHP system can be determined by:
a) Calculating the fuel use and emissionsfrom displaced separate heatand power (SHP) (i.e., grid-supplied
electricity and on-site thermal generation such as a boiler)
b) Calculating the fuel use and emissions from CHP
c) Subtracting (b) from (a)
Equation 1 presents the recommended approach for calculating the fuel savings of a CHP system. Equation 2
presents the recommended approach for calculating C02 emissions savings of a CHP system.
Note: Sections 3.1 and 3.2 present the approaches for calculating the individual terms found in Equations 1 and
2. Appendix A presents a sample calculation of CChsavings using the EPA CHP CEESC which uses the methodology
and equations outlined in this section.
CHP Emission Reductions
CHP systems reduce emissions of
greenhouse gases, criteria pollutants, and
hazardous air pollutants by combusting
less fuel to produce the same amount of
energy as separate heat and grid-delivered
power. The methodology presented in this
paper focuses on the six pollutants in the
CHP Energy and Emission Savings
Calculator but can be used to calculate the
reduction of other pollutants.
9 The thermal output from CHP can also be used to produce cooling in an absorption or adsorption chiller. Accounting for cooling introduces
complexities that are not addressed in the methodology presented in this paper. However, the CEESC does account for cooling.
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Equation 1: Calculating Fuel Savings from CHP
Fs
(Fj + Fg) — Fchp
where:
Fs
Ft
Fg
Fchp
Total Fuel Savings (Btu)
Fuel Use from Displaced On-site Thermal Production (Btu)
Fuel Use from Displaced Grid Electricity (Btu)
Fuel Used by the CHP System (Btu)
Step 1: Calculate Ft and Fg using Equation 3 (page 8) and Equation 6 (page 11), respectively.
Step 2: Calculate Fchp through direct measurement or using Equations 8 (page 12), 9 (page 13) or 10 (page 13).
Step 3: Calculate Fs.
Cchp = CO2 Emissions from the CHP System (lbs CO2)
Step 1: Calculate Ct and Cg using Equation 4 (page 9) and Equation 7 (page 11), respectively.
Step 2: Calculate Cchp using Equation 11 (page 14).
Step 3: Calculate Cs.
Note on using Equations 1 and 2 for bottoming cvcle CHP systems: In the case of bottoming cycle CHP, also
known as waste heat to power, power is generated on site from the hot exhaust of a furnace or kiln with no
additional fuel requirement. Therefore, the fuel use and CO2emissions for both the CHP system and displaced
thermal energy (Fchp, Cchp, Ft, and Ct) are all zero.
Equation 2: Calculating CO2 Savings from CHP
(Ct + Cg) — Cchp
where:
Cs = Total CO2 Emissions Savings (lbs CO2)
Ct = CO2 Emissions from Displaced On-site Thermal Production (lbs CO2)
Cg = CO2 Emissions from Displaced Grid Electricity (lbs CO2)
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3.1 Fuel Use and CO2 Emissions from Displaced On-site Thermal Production
and Displaced Grid Electricity
3.1.1 Fuel Use and CO2 Emissions from Displaced On-site ThermalProduction
The thermal energy produced by a CHP system displaces combustion of some or all of the fuel that would
otherwise be consumed for on-site production of thermal energy.10 The fuel and C02 emissions savings
associated with this displaced fuel consumption can be calculated using the thermal output of the CHP system
and reasonable assumptions about the efficiency characteristics of the equipment that would otherwise have
been used to produce the thermal energy being produced by the CHP system.
Equation 3 presents the approach for calculating the fuel use from displaced on-site thermal production.
Equation 4 presents the approach for calculating the C02emissions from displaced on-site thermal production.
Table 1 lists selected fuel-specific C02 emissions factors for use in Equation 4.
Equation 3: Calculating Fuel Use from Displaced On-site Thermal Production
Ft
CHPt / Qt
where:
Ft
CHPt
Qt
Fuel Use from Displaced On-site Thermal Production (Btu)
CHP System Thermal Output (Btu)
Estimated Efficiency of the Thermal Equipment (percentage in decimal form)
Step 1: Measure or estimate CHPt.
Step 2: Select qt (e.g., 80% efficiency for a natural gas-fired boiler, 75% for a biomass-fired boiler).
Step 3: Calculate Ft.
10 In certain circumstances, CHP systems are designed so that supplemental on-site thermal energy production is sometimes utilized.
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Equation 4: Calculating CO2 Emissions from Displaced On-site Thermal Production
CT = Ft * EFf * (1x10 s)
where:
Cj = CO2 Emissions from Displaced On-site Thermal Production (lbs CO2)
Ft = Thermal Fuel Savings (Btu)
EFf = Fuel Specific CO2 Emission Factor (lbs CO2/MMBtu)
lxlO"6 = Conversion factor from Btu to MMBtu
Step 1: Calculate Ft using Equation 3.
Step 2: Select the appropriate EFf from Table 1.
Step 3: Calculate CT.
Table 1: Selected Fuel-Specific Energy and CO2 Emissions Factors
Fuel Type
Energy Density
C02 Emissions
Factor, Ib/MMBtu
Natural Gas
1,028 Btu/scf
116.9
Distillate Fuel Oil #2
138,000 Btu/gallon
163.1
Residual Fuel Oil #6
150,000 Btu/gallon
165.6
Coal (Anthracite)
12,545 Btu/lb
228.6
Coal (Bituminous)
12,465 Btu/lb
205.6
Coal (Subbituminous)
8,625 Btu/lb
214.2
Coal (Lignite)
7,105 Btu/lb
215.4
Coal (Mixed-Industrial Sector)
11,175 Btu/lb
208.7
Source: 40 CFR Part 98, Mandatory Greenhouse Gas Reporting, Table C-l: Default CO2; Emissions factors and High
Heat Values for Various Types of Fuel.
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3.1.2 Fuel Use and CO2 Emissions from Displaced Grid Electricity
Grid electricity savings associated with on-site CHP include the grid electricity displaced by the CHP output and
related transmission and distribution losses.
When electricity is transmitted along power lines, some of the electricity is lost. The amount of electricity
delivered to users11 is therefore less than the amount generated at central station power plants, with a 5.1
percent United States average.12,13 Consequently, generating 1 MWh of electricity on site means that more
than 1 MWh of electricity no longer needs to be generated at central station power plants to account for
transmission and distribution losses.14 Fuel and C02 emissions savings from displaced grid electricity are based
on the corresponding amount of displaced grid electricity generated and not on the amount of grid electricity
delivered (and consumed).
Equation 5 presents the approach for calculating the displaced grid electricity resulting from electricity
production by on-site CHP. Once the displaced grid electricity from CHP is determined, the fuel use (Equation
6) and C02 emissions (Equation 7) from displaced grid electricity can be calculated.
Equation 5: Calculating Displaced Grid Electricity from CHP
Eg = CHPe /(I-Lt&d)
where:
Eg = Displaced Grid Electricity from CHP (kWh)
CHPe = CHP System Electricity Output (kWh)
Lt&d = Transmission and Distribution Losses (percentage in decimal form)
Step 1: Measure or estimate CHPe.
Step 2: Select Lt&d. (Use the eGRID transmission and distribution loss value for the appropriate U.S. interconnect
power grid*)
Step 3: Calculate EG.
* eGRID lists the estimated transmission and distribution loss for each of the five U.S. interconnect power grids (i.e., Eastern, Western,
ERCOT, Alaska, and Hawaii). (eGRID Technical Support Document:
http://www.epa.gov/cleanenergy/documents/egridzips/eGRID2012 vear09 TechnicalSupportDocument.pdf).
11 For clarity, the amount of electricity generated by a central station power plant is referred to as "generated" electricity, and the amount of
electricity consumed by a facility supplied by the grid is referred to as "delivered" electricity.
12 eGRID2019 Technical Guide. February 2021. https://www.epa.gov/egrid/egrid-technical-support-document
13 DOE Energy Information Administration. State Electricity Profiles, https://www.eia.gov/electricitv/state/
14 For example, assume a consumer without CHP requires 1.0 MWh of electricity each year and T&D losses equal 8%. The delivered electricity is
1.0 MWh/yr, and the generated electricity is 1.087 MWh/yr (= 1/(1-0.08)).
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Note: The key factors required to calculate the fuel use and CO2 emissions from displaced grid electricity are
the heat rate and C02 emissions factor associated with the displaced grid electricity. The tool offers two
options to estimate emissions savings: EPA's AVoided Emissions and geneRation Tool (AVERT) and EPA's
Emissions & Generation Resource Integrated Database (eGRID). In this example, eGRID factors are used. The
CHP fuel and CO2 emissions savings calculations would be based on the heat rates and emissions factors of the
eGRID subregion where the CHP system is located, utilizing the eGRID all fossil or non- baseload emissions
factors as appropriate. See Appendix B for further information on how best to select the appropriate emission
factor.
Equation 6: Calculating Fuel Use from Displaced Grid Electricity
Fg = Eg * HRg
where:
Fg = Fuel Use from Displaced Grid Electricity (Btu)
Eg = Displaced Grid Electricity from CHP (kWh)
HRg = Grid Electricity Heat Rate (Btu/kWh) for the appropriate subregion
Step 1: Determine Eg using Equation 5.
Step 2: Select HRg for the appropriate subregion. (See Appendix B for information about appropriate values and to
identify appropriate emissions factors as a source for grid electricity heat rates.)
Step 3: Calculate FG.
Equation 7: Calculating CO2 Emissions from Displaced Grid Electricity
CG = Eg * EFg
where:
Cg = CO2 Emissions from Displaced Grid Electricity (lbs CO2)
Eg = Displaced Grid Electricity from CHP (kWh)
EFg = Grid Electricity Emissions Factor (lbs CO2 /kWh) for the appropriate subregion
Step 1: Determine Eg using Equation 5.
Step 2: Select EFg for the appropriate subregion. (See Appendix B for information about appropriate values and to
identify appropriate emissions factors as a source for grid electricity C02 emissions factors).
Step 3: Calculate Cg-
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3.2 Fuel Use and CO2 Emissions of the CHP System
The energy content of the fuel consumed by the CHP system (Fchp in Equation 1) can be determined through
several methods listed below. Direct measurement (Method 1) produces the most accurate results but when
that is not an option, the Partnership recommends the use of Methods 2, 3, or 4.
1. Direct measurement of the higher heating value (HHV) of the fuel consumed (typically in MMBtUHHv).
No calculation required.
2. Converting the fuel volume into an energy value (Btu equivalent) using a fuel-specific energy density
using Equation 8.
3. Converting the fuel weight into an energy value (Btu equivalent) using a fuel-specific energy density
(mass basis) using Equation 9.
4. Applying the electrical efficiency of the CHP system to the CHP system's electric output using Equation
10.
Equation 8: Calculating Energy Content of the Fuel Used by CHP from the Fuel Volume
Fchp
Vf * EDf
where:
Fchp
Vf
EDf
Fuel Used by the CHP System (Btu)
Volume of CHP Fuel Used (cubic foot, gallon, etc.)
Energy Density of CHP Fuel (Btu/cubic foot, Btu/gallon, etc.)
Step 1: Measure or estimate Vf.
Step 2: Select the appropriate value of EDf. (See Table 1 on page 9)
Step 3: Calculate Fchp-
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Equation 9: Calculating Energy Content of the Fuel Used by CHP from the Fuel Weight
Fchp = WF * EDf
where:
Fchp = Fuel Used by the CHP System (Btu)
Wf = Weight of CHP Fuel Used (lbs)
EDf = Energy Density of CHP Fuel - Mass Basis (Btu/lb)
Step 1: Measure or estimate Wf.
Step 2: Select the appropriate EDf. In order to be used here, the values in Table 1 (page 9) must be converted to a
mass basis using the fuel-specific density.
Step 3: Calculate Fchp-
Equation 10: Calculating Energy Content of the Fuel Used by CHP from the CHP Electric Output
Fchp (CHPe/ EEchp) * 3412
where:
Fchp = Fuel Used by the CHP System (Btu)
CHPe = CHP System Electricity Output (kWh)
EEchp = Electrical Efficiency of the CHP System (percentage in decimal form)
3412 = Conversion factor between kWh and Btu
Step 1: Measure or estimate CHPe.
Step 2: Determine EEchp- (This value should account for parasitic losses, and is usually available in a product
specification sheet provided by the manufacturer of the equipment.)
Step 3: Calculate Fchp-
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The C02 emissions from the CHP system are a function of the type and amount of fuel consumed. C02emissions
rates are commonly presented as pounds of emissions per million Btu of fuel input (Ib/MMBtu). Table 1 on page
9 lists common fuel-specific CO2 emissions factors. Equation 11 presents the approach for calculating CO2
emissions from a CHP system (inserted as Cchp in Equation 2).
Equation 11: Calculating CO2 Emissions from the CHP System
Cchp = Fchp * EFf
where:
Cchp = CO2 Emissions from the CHP System (lbs CO2)
Fchp = Fuel Used by the CHP System (Btu)
EFf = Fuel Specific Emissions Factor (lbs CO2/MMBtu)
Step 1: Measure or calculate Fchp using Equations 8 (page 12), 9 (page 13), or 10 (page 13).
Step 2: Select the appropriate EFf from Table 1 on page 9.
Step 3: Calculate Cchp, the CO2 emissions from the CHP system.
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APPENDIX A
CEESC EXAMPLE CALCULATION
The EPA CHP Energy and Emissions Savings Calculator (CEESC) allows users to calculate the fuel savings and
emissions reductions 15 of CHP using the approach described in this guidance. The default values in the CEESC
are based on the guidelines in this paper. However, the tool also allows users to input user-selected CHP system
characteristics and emissions factors for CHP fuel, displaced thermal fuel, and displaced grid electricity.
The CEESC is available at: https://www.epa.gov/chp/chp-energy-and-emissions-savings-calculator.
For this example calculation, the CHP system is assumed to be a 5 MW natural gas-fired combustion turbine
CHP system that provides heating for an industrial process at a facility located in eastern Pennsylvania. The CHP
system will displace thermal energy provided by an existing natural gas boiler and will also displace grid
electricity.
A.l Calculator Inputs
The CEESC has five main input categories to be completed sequentially:
1. CHP System Characteristics: type of system, size, fuel used, etc.
2. CHP Cooling Characteristics: if absorption chillers are used for cooling
3. Thermal Characteristics: displaced thermal equipment
4. Electricity Profile: displaced grid electricity
5. CHP & Displaced Boiler Emissions Characteristics: emissions factors for on-site fuel consumption
The input data is shown with the help of several figures, snapshots from the actual calculator, to guide the
user's understanding. Figure A-l shows the inputs related to the example CHP system. For this example, the
CHP characteristics of the hypothetical system and default values for the electric efficiency and CHP power-to-
heat ratio, based on the selected technology, were used.
15 The CEESC estimates changes in carbon dioxide (CO2), methane (CH4), nitrogen oxides (NOx), nitrous oxide (N20), sulfur dioxide (S02), and
total greenhouse gases (GHG) emissions.
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Figure A-l: CHP Energy and Emissions Savings Calculator - CHP System Characteristics
1. CHP: Type of System
Combustion Turbine
Submit
2. CHP: Electricity Generating Capacity (per unit)
Normal size range for this technology is 1,000 to 40,000 kW
f 5,OQolkW
3. CHP: How Many Identical Units (i.e., engines) Does This System Have?
1
Submit
4. CHP: Annual Utilization (Enter a value to answer only ONE of the options below)
Option 1: How many hours per year does the CHP system operate?
I will enter a value
As a number of hours per year
OR As a percentage
0%
Option 2: How much grid electricity is displaced by CHP operation each year?
Enter displaced grid electricity as MWh/year| ^
MWh/yr
Submit
5. CHP: Does the System Provide Heating or Cooling or Both?
Heating Only
If Heating and Cooling: How many of the 7,500 hours are in cooling mode?
As a number of hours per year
as a percentage of the 7,500 hours?
0%
If Heating and Cooling: Does the System Provide Simultaneous Heating and Cooling?
6. CHP: Fuel
Fuel Type Natural Gas
View bio mass and coal
fuel characteristics
Submit
10. CHP: Electric Efficiency
I will enter an efficiency in one
of the following blocks
Use default for this technology
Enter Generating Efficiency as
OR Enter Generating Efficiency as Btu/kWh HHV
OR Enter Generating Efficiency as Btu/kWh LHV
11,806
10,684
(HHV)
Btu/kWh (HHV)
Btu/kWh (LHV)
11. CHP Equipment: Base Power to Heat Ratio
The Power to Heat Ratio should reflect ONLY the thermal production of the generating unit (i.e., combustion turbine).
Thermal Output of the duct burners (if equipped) should not be included.
I will enter a Power to Heat ratio | Use default for this technology
See the SubTher ma Calculator for help on calculating a Power to Heat Ratio
Power to Heat Ratio (Generating Unit Capacity)
If WHP Useful Thermal Output (MMBtu/hr)
0.62
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In this example, CHP cooling is not being used, so the next input category is related to displaced on-site thermal
energy use. This is the thermal energy produced by the CHP system and will replace thermal energy formerly
produced by an on-site thermal equipment typically a boiler. In this example, 100 percent of the thermal energy
from CHP is utilized by the host facility, although this factor can be adjusted. Information about the thermal
equipment and the fuel used in it allows a user to calculate the displaced thermal fuel use and CO2 emissions.
Figure A-2 shows the calculator inputs on displaced thermal energy.
Figure A-2: CHP Energy and Emissions Savings Calculator - Displaced Thermal Energy
19. Displaced Thermal: Type of System:
Existing Gas Boiler
Submit
20. Displaced Thermal: What is the Heat Content of the displaced Fuel? (Enter a value in only ONE of the boxes)
Btu/cubic foot (HHV)
OR
OR
1,028
Btu/gallon (HHV)
Btu/lb (HHV)
Submit
21. Displaced Thermal: Efficiency (usually a boiler)
1 will enter an efficiency
Use default for this thermal technology
Submit
Enter Generating Efficiency as %
1
80%
22. Thermal Utilization (Enter a value to answer only ONE of the options below)
Option 1: CHP Thermal Utilization - What is the percent of available CHP thermal output utilized throughout the year?
1 will enter a thermal utilization
Use the default thermal utilization
Submit
Enter thermal utilization as a %
1
100%
(also applies to cooling)
Option 2: Displaced boiler fuel - What is the quantity of boiler fuel displaced throughout the year?
Enter displaced boiler fuel as MMBtu/year - MMBtu/yr
The next input category is the displaced grid electricity shown in Figure A-3 below. There are four types of
displaced electricity generation profiles available: AVERT16, eGRID17 profiles, specific electricity generation
equipment profiles, and user-defined profiles.
The AVERT profile includes the Uniform EE factor for marginal grid emissions based on AVERT region. If an
AVERT emissions factor is selected, the corresponding heat rate from applicable eGRID subregion(s) will be used
to calculate energy savings. More information and considerations for eGRID and AVERT emissions profiles are
contained in Appendix B.
The eGRID emissions profiles include: Total Output Emissions Rate, Fossil Fuel Output Emissions Rate, Non-
Baseload Output Emissions Rate, Coal Output Emissions Rate, Oil Output Emissions Rate, and Gas Output
16 https://www.epa.gov/statelocalenergy/avoided-emissions-and-generation-tool-avert
17 https://www.epa.gov/egrid
17
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Emissions Rate by eGRID subregion. Each eGRID emissions rate also has an associated heat rate that is used to
calculate energy (fuel) savings.
For this example, the AVERT profile was used and the system is assumed to be in the AVERT Mid-Atlantic Region
(that also corresponds to the eGRID RFC East subregion).18 AVERT factors have transmission and distribution
(T&D) losses built in, so it is not necessary to fill that input. If using eGRID, the Partnership recommends using
the eGRID value for grid losses from the appropriate U.S. interconnect power grid. There are five U.S.
interconnect power grids (Eastern, Western, ERCOT, Alaska, and Hawaii), and the appropriate grid for this
example is the Eastern grid, with average T&D losses of 5.4%.
Figure A-3: CHP Energy and Emissions Savings Calculator - Displaced Electricity
23. Displaced Electricity: Electricity Generation Profile
AVERT Uniform EE Factors (2019 Data)
See the instructions for Input 23 in Section 2 of the User Manual
24. Displaced Electricity: Select U.S. Average, eGRID Subregion, NERC region, or AVERT region
AVERT-Mid-Atlantic ~
Link to eGRID Subregion Map. NERC Interconnections Map, and AVERT Region Map
25. Displaced Electricity: Select Electric Grid
A VERT regions already have grid loss included in
emission factors, so default is set to zero
Link to NERC Interconnections Map
The final inputs re related to the emission characteristics of CHP and displaced boiler fuel. With the inputs
entered up to this point, it is possible to calculate energy savings, and this final set of inputs enable emissions
savings to be calculated. Default emissions for sulfur, NOx, and C02 can be selected based on the fuel and
equipment inputs. In this case, to calculate C02 savings from CHP, the default C02 emissions rate for natural
gas (116.9 Ib/MMBtu) is entered in Inputs 27 and 30 (see Figure A-4).
Figure A-4: CHP Energy and Emissions Savings Calculator - Displaced Electricity
27. CHP: What is the C02 Emission Rate for this
Enter alternative value:
Fuel? (default completed for fuel in
116.9
Item 6)
lb C02/MMBtu
Submit
30. Displaced Thermal: What is the C02 Emissio
Enter alternative value:
n Rate for this Fuel? (default comp
116.9'
eted for fuel in Item 23)
lb C02/MMBtu
Submit
The equations for calculating fuel use and CO2 emissions from displaced on-site thermal energy production are:
18 Information about eGRID subregions and grid electricity emissions is contained in Appendix B.
Modify one of the User-
Defined Profiles
Submit
Submit
gion for Transmission and Distribution (T&D) Losses
0.00%1
Submit
18
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Fuel Use from Displaced On-site Thermal Energy Production (Equation 3):
FT=CHPT/r)T
257,964 MMBtu/yr = 206,371 MMBtu/yr / 80%
where:
Ft = Fuel Use from Displaced On-site Thermal Production (Btu)
CFIPt = CHP System Thermal Output (Btu)
qt = Thermal Equipment Efficiency (%)
CO2 Emissions from Displaced On-site Thermal Production (Equation 4):
Ct= Ft* EFf
30,155,992 lbs C02= 257,964 MMBtu/yr * 116.9 lb (Xh/MMBtu
where:
Ct = CO2 emissions from displaced on-site thermal production (lbs CO2)
Ft = Thermal Fuel Savings (Btu)
EFf = Fuel Specific Emissions Factor (lbs (Xh/MMBtu)
The total fuel use and CO2 emissions of displaced grid electricity are calculated using the following equations:
Displaced Grid Electricity from CHP (Equation 5):
Eg= CHPe/ (I-Lt&d)
37,500 MWh/year = 37,500 MWh/year / (1 - 0)
where:
Eg = Displaced Grid Electricity from CHP (kWh)
CFIPe = CHP System Electricity Output (kWh)
Lt&d = Transmission and Distribution Losses (%)
Transmission and distribution losses are not factored into this equation since AVERT emissions factors already
have these losses built in. If using eGRID factors, the loss value would be selected based on the site's
interconnect region.
Fuel Use from Displaced Grid Electricity (Equation 6):
Fg= Eg* HRg
300,437 MMBtu/year = 37,500 MWh/year * 8,012 Btu/kWh / 1000*
*Note: numbers may not equate exactly due to rounding.
where:
Fg = Fuel Use from Displaced Grid Electricity (Btu)
Eg = Displaced Grid Electricity from CHP (kWh)
HRg = Grid Electricity Heat Rate (Btu/kWh)
19
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C02 Emissions from Displaced Grid Electricity (Equation 7):
Cg= Eg* EFg
57,744,100 lbs C02= 37,500 MWh/year * 1,539.8 lb CCh/MWh
*Note: numbers may not equate exactly due to rounding.
where:
Cg = C02 Emissions from Displaced Grid Electricity (lbs)
Eg = Displaced Grid Electricity from CHP (MWh)
EFg = Grid Electricity Emissions Factor (CO2 Ib/MWh)
A.2 Calculator Results
Once the user has entered all the information on the Inputs page and clicked the "Go to Results" button, the
Results page is displayed. Figure A-5 illustrates the results for this example, which shows that the CHP system
reduces overall fuel consumption by 115,546 MMBtu/year and CO2 emissions by 18,065 tons/year. The two
icons show the GFIG equivalency of the savings compared to the emissions from passenger vehicles and the
emissions generated from electricity used for single family homes' energy use.
20
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CHP Results
The results generated by the CHP Energy and Emissions Savings Calculator are intended for educational and outreach purposes only;
it is not designed for use in developing emission inventories or preparing air permit applications.
The results of this analysis have not been reviewed or endorsed bv the EPA CHP Partnership.
Table 1: Annual Energy Savings
CHP System
Displaced
Electricity
Production
Displaced Thermal
Production
Fuel Savings
Percent Savings
Fuel Consumption (MMBtu/year)
442,855
300,437
257,964
115,546
21%
Equal to the annual energy consumption of this many passenger vehicles:
1,827
Equal to the annual energy consumption from the generation of electricity for this many homes:
1,184
Table 2: Annual Emissions Savings
CHP System
Displaced
Electricity
Production
Displaced Thermal
Production
Emissions Savings
Percent Savings
NOx (tons/year)
20.35
13.77
51.59
45.01
69%
S02 (tons/year)
0.13
22.10
0.08
22.04
99%
C02 (tons/year)
25,885
28,872.05
15,078
18,065.17
41%
CH4 (tons/year)
0.49
1.54
0.28
1.34
73%
N20 (tons/year)
0.05
0.21
0.03
0.19
80%
Total GHGs (C02e tons/year)
25,910
28,970.92
15,093
18,153.44
41%
Equal to the annual GHG emissions from this many passenger vehicles:
3,557
Equal to the annual GHG emissions from the generation of electricity for this many homes:
1,899
Equal to the annual greenhouse
gas emissions from
3,557 passenger vehicles.
Equal to the annual greenhouse
gas emissions from the generation of
electricity used by 1,899 homes.
Passenger vehicles
driven for one year
it
Homes' energy use
for one year
Figure A-5: CHP Energy and Emissions Savings Calculator - Fuel and Emissions Savings Results
Figure A-6 shows the outputs of the CHP system in more detail, and Figure A-7 shows the emissions rates for
the CHP system as well as those from the displaced thermal production and displaced electricity generation.
The equations for the relationship for total fuel savings and CO2 savings are as follows:
Total Fuel Savings from CHP (Equation 1):
Fs = (Ft+ Fg) - Fchp
115,546 MMBtu/year= (257,964 MMBtu/year + 300,437 MMBtu/year) -442,855 MMBtu/year
where:
Fs
Ft
Fg
= Total Fuel Savings
= Fuel Use from Displaced On-site Thermal Production
= Fuel Use from Displaced Grid Electricity
21
-------
Fchp = Fuel Used by the CHP System
Total CO2Savings from CHP (Equation 2):
Cs = (Ct+ Cg) - Cchp
18,065 tons CC>2= (15,078 tons + 28,872 tons) - 25,885 tons
where:
Cs = Total CO2 Emissions Savings
Ct = CO2 Emissions from Displaced On-site Thermal Production
Cg = CO2 Emissions from Displaced Grid Electricity
Cchp = CO2 Emissions from the CHP System
Figure A-6: CHP Energy and Emissions Savings Calculator - CHP Outputs
Table 3: CHP Technology and Generation Profile
CHP Technology
Fuel
Unit Capacity
Number of Units
Total CHP Capacity
Operation
Heat Rate
Combustion Turbine
Natural Gas
5,000 kW
1
5,000 kW
7,500 hours per year
11,809 Btu/kWh HHV
CHP Fuel Consumption
Duct Burner Fuel Consumption
Total Fuel Consumption
442,855 MMBtu/year
MMBtu/year
442,855 MMBtu/year
Total CHP Generation
37,500 MWh/year
Useful CHP Thermal Output
206,371 MMBtu/year for thermal applications (non-cooling)
MMBtu/year for electric applications (cooling and electric heating)
206,371 MMBtu/year Total
Table 4: Displaced Thermal Energy
Displaced On-Site Production for
Existing Gas Boiler
Thermal (non-cooling) Applications:
0.40 Ib/MMBtu NOx
0.00% sulfur content
Displaced Electric Service (cooling and electric
heating):
There is no displaced cooling service
Table 5: Displaced Electricity
Displaced Electricity Profile: AVERT Uniform EE Factors (2019 Data)
eGRID/NERC Region: AVERT
Mid-Atlantic
Distribution Losses:
0.0%
Displaced Electricity Production:
37,500 MWh/year CHP generation
MWh/year Displaced Electric Demand (cooling)
MWh/year Displaced Electric Demand (electric heating)
MWh/year Transmission Losses
37,500 MWh/year Total
22
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Figure A-7: CHP Energy and Emissions Savings Calculator - Emissions Rates
Table 6: Annual Analysis for CHP
CHP System:
Combustion
Duct Burners (if
Total Emissions
Turbine
applicable)
from CHP System
N0X (tons/year)
20.35
-
20.35
S02 (tons/year)
0.13
-
0.13
C02 (tons/year)
25,885
-
25,885
CH4 (tons/year)
0.49
-
0.49
N20 (tons/year)
0.05
-
0.05
Total GHGs (C02e tons/year)
25,910
-
25,910
Carbon (metric tons/year)
6,400
-
6,400
Fuel Consumption (MMBtu/year)
442,855
-
442,855
Table 7: Annual Analysis for Displaced Thermal Production (non-cooling)
Total Displaced
Emissions from
Thermal
Production
NOx (tons/year)
51.59
S02 (tons/year)
0.08
C02 (tons/year)
15,078
CH4 (tons/year)
0.28
N20 (tons/year)
0.03
Total GHGs (C02e tons/year)
15,093
Carbon (metric tons/year)
3,728
Fuel Consumption (MMBtu/year)
257,964
Table 8: Annual Analysis for Displaced Electricity Production
Displaced CHP
Electricity
Generation
Displaced
Electricity for
Cooling
Displaced
Electricity for
Heating
Transmission
Losses
Total Displaced
Emissions from
Electricity
Generation
NOx (tons/year)
13.77
-
-
-
13.77
S02 (tons/year)
22.10
-
-
-
22.10
C02 (tons/year)
28,872
-
-
-
28,872
CH4 (tons/year)
1.541
-
-
-
1.541
N20 (tons/year)
0.215
-
-
-
0.215
Total GHGs (C02e tons/year)
28,971
-
-
-
28,971
Carbon (metric tons/year)
7,139
.
.
.
7,139
Fuel Consumption (MMBtu/year)
300,437
-
-
-
300,437
23
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Figure 1. Conventional Production Energy Flow Schematic
Figure 2. CHP System Energy Flow Schematic
Total Emissions for Conventional Production
65.36 tons of NOx
22.17 tons of SO 2
44,064 tons of C02e
300,437 MMBtu
Fuel consumption
257,964 MMBtu
Fuel consumption
Central Station
Power Plant
13.77 tons of NOx
22.1 tons of S02
28,971 tons of C02e
51.59 tons of NOx
.08 tons of S02
15,093 tons of C02e
37,500 MWh
Electricity to Facility
No Cooling
MWh
Transmission Losses
On-Site Thermal
Production
206,371 MMBtu
Thermal to Facility
Total Emissions for CHP System
20.35 tons of NOx
.13 tons of SO 2
25,910 tons of C02e
442,855 MMBtu
Fuel Consumption
20.35 tons of NOx
.13 tons of S02
25,910 tons of C02e
C
37,500 MWh
Electricity
to Facility
Thermal Energy from CHP
06,371 MMBtu
Thermal to
Facility
Absorption
Chiller
No Cooling
Annual Energy and Emissions Savings from CHP
115,546 MMBtu of fuel
45.01 tons of NOx
22.04 tons of S02
18,065 tons of C02e
24
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APPENDIX B ESTIMATING DISPLACED GRID ELECTRICITY FUEL USE AND C02
EMISSIONS
This appendix supplements the methodology provided in Section 3.1.2, on how to estimate the displaced fuel
use and CO2 emissions from a CHP system, and provides information on how to select appropriate grid emission
factors and grid electricity heat rate. The methodology can be summarized in three steps:
a) Calculate the fuel use and emissions from displaced separate heat and power (SHP) (i.e., grid-supplied
electricity and on-site thermal generation such as a boiler)
b) Calculate the fuel use and emissions from CHP
c) Determine the displaced fuel use CO2 emissions by subtracting Step (b) from Step (a)
To complete Step (a), the appropriate grid emission factor and grid electricity heat rate need to be selected.
Grid-supplied electricity is generated by many sources with different fuels and heat rates and the sources that
are reasonably expected to be displaced are determined to estimate the displaced fuel use and emissions. Once
the grid emission factor is identified, the corresponding grid electricity heat rate is then used to determine the
fuel savings from the CHP.
Key Takeaways
CEESC users are recommended to use AVERT factors by default, as they use a more rigorous
and sophisticated method of estimating marginal displaced grid emissions. However, for end
users that meet the following criteria, eGRID may be the preferred option:
• Heat rate information is desired for energy savings calculations (heat rate data is tied
to eGRID subregions).
• Grid emissions data for CH4 and N20 is desired (found in eGRID, used in calculating C02-
equivalent emissions).
• End user is located in one of four AVERTs region that corresponds to multiple eGRID
subregions: Central and Mid-Atlantic that have two corresponding eGRID subregions,
and Midwest and New York that have three corresponding eGRID subregions.
• End user is located in Alaska, Hawaii, or Puerto Rico.
The appendix is divided in the following sections:
i. Section B.l - An explanation of how displaced grid emissions are estimated using load duration curves
and grid dispatch order.
ii. Section B.2 - An overview of different methods of estimating displaced grid emissions
a. Sophisticated Methods
b. Intermediate Methods
c. Basic Methods
iii. Section B.3 - An explanation of EPA's AVoided Emissions and geneRation Tool (AVERT) and how it can
be used to estimate the grid electricity emissions factor (EFg) to calculate the CO2 emissions associated
with displaced grid electricity from CHP.
25
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iv. Section B.4 - An explanation of EPA's Emissions & Generation Resource Integrated Database (eGRID) as
a resource for the grid electricity heat rate (HRg) and the grid electricity emissions factor (EFg) to
calculate the fuel and CO2 emissions associated with displaced grid electricity from CHP.
v. Section B.5 - The Partnership's recommendations on appropriate grid emission factors and grid
electricity heat rate for the Emissions Calculator.
B.l Load Duration Curves and Grid Dispatch Order
In a competitive electric market, generators are dispatched based on their bid price into the market (typically
a function of the variable costs of generation, fuel, other consumable items, and operation and maintenance
costs19). Generators serving the electric grid are dispatched in order of operating cost - lowest to highest:
• The generators with the lowest operating cost (nuclear, hydroelectric, and renewable) supply electricity
to the grid whenever they are available. This is illustrated in Figure B-l, which shows that these
generators operate continuously over the entire year.
• Combined cycle gas plants and coal generation are typically the grid resources with the next-lowest
operating cost. While these plants largely serve as baseload plants, there are periods in which power
must be scaled back or turned off during periods of low demand.
• Simple cycle natural gas and oil-fired systems typically have the highest operating costs, and therefore
operate the fewest number of hours. They are also well suited for intermediate and peaking loads, as
simple cycle systems can ramp up and down faster than combined cycle or coal systems to meet
marginal loads. The generators with the very highest operating costs are typically only used to meet
peaking loads.
When a CHP system is operated as a distributed generation source at a site, electricity demand from the
wholesale electricity grid is reduced commensurate with the electricity the CHP generates. Certain generation
resources, those at the top of the grid dispatch order, will no longer be required to serve the total customer
load. These generation resources will now be used to serve incremental customer loads as grid demand changes
through the day.
Demand for electricity varies widely over the year, and different types and sizes of generators are used to meet
the varying load as it changes. A load duration curve represents the electric demand in MW for a specific region
or subregion for all 8,760 hours in a year, arranged in descending order.
Figure B-l shows a representative CHP load duration curve for a hypothetical power control area (PCA). The
shape of the curve is typical of electric load duration curves. Demand (in MW) is indicated on the vertical axis
and the number of hours of the year the system is operated are indicated on the horizontal axis. The area under
the load duration curve represents the total generation for the year. The zones defined by colored bands
represent a typical generating mix and dispatch order. The dispatch order is dependent on the demand and the
relative costs of serving customer loads20.
This example shows a simplified load duration curve created for a CHP system and dispatch order for the
hypothetical PCA. The PCA has a maximum demand of 10,000 MW that occurs in the first hour of the annual
19 Electric generator dispatch depends on system demand and the relative cost of operation, accessed at
https://www.eia. gov/todavinenergy/detail.php?id=7590.
20 One example is provided by the PJM regional transmission organization. Refer to "How PJM Schedules Generation to Meet Demand" at
https://learn.pim.com/three-priorities/keeping-the-lights-on/how-pim-schedules-generation-to-meet-demand.aspx.
26
-------
operation (between 0 hours and 1 hour on the curve). During this hour, all available resources, including peaking
units, are deployed. At the 8,760-hour mark (the right-most point on the chart) that corresponds to load
required to meet the last hour of the annual demand for this hypothetical year, the resources below the black
line are used to meet a minimum demand of 4,000 MW.
Figure B-l: Hypothetical Power System Load Duration Curve and Dispatch Order
10000
9000
8000
7000
g 6000
£
ra 5000
Q.
nj
O
5 4000
3000
2000
1000
0
0 1000 2000 3000 4000 5000 6000 7000 8000
Hours/year
Gas and Oil Intermediate
load0u-^;—
Combined Cycle Gas
and Coal
0)
cj
&_
O
_c
u
Wind and Solar
4—>
03
Q_
iS)
Q
Nuclear and Hydro
Figure B-2 illustrates the effect of CHP capacity that continuously avoids 1,000 MW of central power generation
in the hypothetical PCA. For simplicity, it is assumed that the CHP system operates 24/7 for the entire year even
though CHP systems may be offline for several days a year for planned or unplanned maintenance. In the figure,
we observe the following:
i. Because the CHP capacity operates continuously, the load duration curve shifts downward to reflect
the 1,000 MW reduction in demand for all hours of the year.
ii. Compared to the base case (the top curve), the additional CHP capacity displaces an equal amount of
generation each hour that it runs, shifting the load curve down while it runs. The CHP system displaces
power from the last unit of generation that would have been dispatched in each of these hours.
iii. Depending on the hour, the displaced generator could be a coal, oil, or gas steam unit, a combined
cycle generator, a central station peaking turbine, or a reciprocating engine peaking unit.
iv. Generators with a lower dispatch order, such as nuclear, hydro, and renewables, are unaffected. These
resources generate electricity whenever they are available so are unaffected by changes in power
demand that result from CHP additions.
27
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v. The grid generation (and corresponding emissions) displaced with CHP is therefore the output
represented by the shaded area in the chart—a mix of mostly baseload and intermediate generation
with some peaking generation, all from fossil fuel resources.
Figure B-2: Marginal Displaced Generation due to 1,000 MW of CHP
10000
9000
8000
Gas and Oil Peaking
7000
Gas and Oil Intermediate
5 6000
5
>¦
ra 5000
Gi-
ro
U
~0
*5 4000
"c/e£/pc
WhcHp
Combined Cycle Gas and
Coal
3000
2000
Wind and Solar
1000
Nuclear and Hydro
1000 2000 3000 4000 5000
Hours/year
6000
7000
8000
B.2 Methods for Estimating Displaced Grid Emissions
There are different methods that can be used to quantify emissions reductions from displaced grid generation,
each answering different analytical questions with varying levels of rigor, assumptions, resource requirements,
data needs, and temporal and spatial scales of emission outputs. Each method is intended to quantify the
avoided or displaced emissions from grid system generation due to energy efficiency, renewable energy, or
distributed energy resources (such as CHP) that displace grid electricity. The level of sophistication of each grid
emissions quantification approach is inversely related to the complexity of assumptions in each approach.
Figure B-3 below shows how the level of sophistication of the approaches increases as you go from basic
straightforward emissions calculations to complex modeling.21
21 U.S. EPA, Quantifying the Emissions and Health Benefits of Energy Efficiency and Renewable Energy, Part Two, Chapter 4,
https://www.epa.eov/sites/production/files/2018-07/documents/mbe 2-4 emissionshealthbenefits.pdf
28
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Figure B-3: Methods for Estimating Displaced Grid Emissions22
Basic
Intermediate
Sophisticated
eGRID
Subregion
Emission Rates
Approach
Emission Rates
AVERT
Historical
Hourly
Energy
Modeling
Approach
Sophisticated methods use energy-related models that represent the interplay of futuristic assumptions
within the electricity or energy system to determine emission impacts. To calculate the effects on emissions,
these methods provide detailed forecasts of regional supply and demand in relation to multiple factors such
as emissions controls, fuel prices, dispatch sequences and associated changes, and new generation resources.
Sophisticated dispatch models result in more rigorous estimates of emissions impacts as compared to basic-
to-intermediate methods, but these models and methods are resource intensive.
Intermediate methods use hourly load profiles to reflect time-of-day impacts throughout the year and use
electric generating unit (EGU)'s dispatch patterns to assess impacts. EPA's AVoided Emissions and geneRation
Tool (AVERT) factors are derived taking this approach. By taking into account time-of-day impacts, intermediate
methods can use historical data to capture the impact of current and certain future activities. Analysts have
been known to use these methods to compare the emissions impacts of existing or planned energy efficiency
and renewable energy policies and programs from the county to the state level such as agency staff and state
air quality planners interested in assessing emission benefits incorporated into Clean Air Act plans to meet
the National Ambient Air Quality Standards.
Basic methods assume consistent energy savings throughout the year and assign marginal emissions rates or
specific emissions rates for proxy unit types based on historical data rather than accounting for hourly load
profiles for the year or considering dispatch patterns. EPA's Emissions & Generation Resource Integrated
Database (eGRID23) factors are derived taking this approach, These methods offer a simplified analysis of
capturing complex data and can be used to support activities where a snapshot of different emission factors
are necessary. For example, eGRID data can be used for greenhouse gas registries and inventories, carbon
footprinting, consumer information disclosure and analysis of changing power markets.
The CEESC is a location-specific tool that can use either AVERT or eGRID emissions factors to estimate
displaced grid emissions and offer a preliminary analysis of emission reductions from CHP. The rest of this
Appendix provides a better understanding on how both sets of emissions factors can be used in the CEESC.
22 https://www.epa.gov/statelocalenergy/avoided-emissions-and-generation-tool-avert
23 https://www.epa.gov/egrid
29
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B.3 EPA's AVoided Emissions and geneRation Tool (AVERT)
EPA's AVoided Emissions and geneRation Tool (AVERT) is a web-based tool that uses an intermediate method
to estimate the fine particulate matter (PM2.5), carbon dioxide (C02), nitrogen oxides (NOx), and sulfur dioxide
(S02) emissions avoided at electric power plants by energy efficiency and renewable energy policies, programs,
and projects. AVERT uses historical hourly emissions rates based on recent EPA data on EGUs' hourly generation
and emissions reported through EPA's Acid Rain Program.24 This method combines historical hourly generation
and emissions with the hourly load profiles of energy resources to determine hourly marginal emissions rates
and hourly changes in emissions.
Emissions and Heat Rate Data
When using AVERT, users receive the following outputs:
• NOxemissions reductions
• S02emissions reductions
• C02 emissions reductions
• Marginal Emissions Rates
• Emissions associated with power generation in the United States.
AVERT utilizes data collected by the EPA Clean Air Markets Division (CAMD) on fossil-fuel electric generating
units subject to 40 CFR 75,25 comprised of units greater than 25 MW and other units subject to the rule. Data
collected and reported by CAMD includes the following:
• Plant
• State
• Electric generating company (EGC)
• Gross Generation
• Heat Input
• Emissions of NOx, S02, & C02
AVERT consists of historic sets of recent data compiled annually and enables analysis in near term future years.
The generation data and related data categories provided by AVERT are based on consumed electricity and
include the impact of transmission and distribution (T&D) losses (see Section 3.1.2 and Equation 5 for more
information on T&D losses).
The AVERT data is aggregated into 14 regions (see Figure B-4), which are based on one or multiple balancing
authorities. Each AVERT region consists of at least one balancing authority, with most encompassing multiple
balancing authorities. AVERT regions generally represent sections of the grid that have similar resource mix and
emissions characteristics and are similar to the regional assignments from ElA's 930 dataset. Alaska and Hawaii
are not included in AVERT regions or analysis since there is limited data on units from the two states in the
CAMD data.
24 See EPA's Power Sector Emissions Data at https://ampd.epa.gov/ampd/
25 40 CFR 75 accessed at https://www.ecfr.gov/cgi-bin/text-
idx?SID=f2e2623eb620fa4el65b39dd865ff713&mc=true&node=pt40.18.75&rgn=div5#se40.18.75 12
30
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Figure B-4: AVERT Region Map
AVERT Emissions Data
AVERT collects usage data at an hourly level from EGUs to understand which power plants are generating
energy at a given time and how that impacts emissions. AVERT outputs displaced marginal grid emissions based
on energy efficiency programs and improvements by estimating how they displace individual fossil fuel EGU in
a region. AVERT provides displaced emissions data for CO2, S02, NOx, and PM2.5 emissions.
AVERT does not provide heat rates. For the purpose of the CEESC, when using the AVERT emission factors, heat
rates are calculated by using eGRID Fossil Fuel Output heat rate values. AVERT regions that encompass multiple
eGRID regions use a calculated heat rate proportional to the eGRID regions that comprise the AVERT region.
Selecting the Appropriate AVERT Emissions Factor
The AVERT tool can estimate specific emissions reductions based on user-supplied hourly kWh data for detailed
planning and custom analysis that accounts for seasonal and time-of-day variations. However, EPA has also
developed emissions factors for AVERT based on pre-defined load patterns and assuming a 0.5% displacement
of the existing demand in each of AVERT's 14 regions. These regional emissions factors, estimating displaced
grid emissions in units of pounds per MWh, are divided into six categories: wind (onshore and offshore),
photovoltaic (PV) (utility and distributed), portfolio EE, and uniform EE. EPA recommends that these emissions
factors be used for general estimates of avoided emissions from renewable energy or energy efficiency
programs, policies, or projects.26,27 A summary description of these factors are provided below and more details
can be found in the AVERT manual.
• Wind, Both AVERT wind emissions factors are based on load patterns for wind farms following typical
generation profiles with respect to wind resource availability in each region.
26 EPA, "Emissions Factors from AVERT", https://www.epa.gov/sites/production/files/2019-05/documents/avert emission factors 05-30-
19 508.pdf
27 EPA, "AVERT User Manual: Version 3.0", https://www.epa.gov/sites/production/files/2020-09/documents/avert user manual 09-12-
20 508.pdf
31
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• PV. AVERT PV emissions factors focus on the impact of rooftop and utility PV on grid emissions
reductions. Each AVERT region has unique solar emissions factors based on the region's solar insolation
and grid fossil fuel generation.
• Portfolio EE. Portfolio EE emissions represent avoided emissions for a typical portfolio of energy
efficiency resources, incorporating seasonal and time-of-day differences in energy efficiency savings
and comparing to grid fossil fuel generation.
• Uniform EE. Uniform EE factors are used for programs that provide consistent energy savings in the
form of constant load reductions over the course of a year compared to grid fossil fuel generation.
Wind and PV factors represent highly variable loads that are not representative of CHP generation. Between
the Portfolio EE and Uniform EE factors, Uniform EE factors more closely resemble CHP operation as they
represent a constant non-variable reduction in grid electricity requirements. Most CHP systems operate
consistently at or near full capacity, producing the same constant reduction in grid electricity. In Figure B-5, the
load duration curve illustrates the approximate constant load reductions on the grid marginal emissions with
AVERT's Uniform EE factors.
While Uniform EE factors most closely represent a system that is operating 24/7, they also provide a close
representation of avoided emissions from CHP systems that primarily operate during day and evening hours.
The Partnership conducted an analysis in 2018 to assess the difference between 24/7 operation and typical
commercial operating regimes for daytime/evening CHP. The analysis showed that avoided grid emissions from
CHP tracked closely to the Uniform EE factor for both operating regimes. Results of the analysis are summarized
in Table B-l.
32
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Figure B-5. Marginal Emissions Estimated with AVERT Uniform EE Factor
10000
9000
Gas and Oil Peaking
8000
7000
Gas and Oil Intermediate
| 6000
4-J
ro 5000
Q.
ro
U
"O
5 4000
AVl*Tun«
f°i~rn ££
Combined Cycle Gas and
Coal
3000
2000
Wind and Solar
1000
Nuclear and Hydro
1000 2000 3000 4000 5000
Hours/year
6000
7000
8000
Table B-l. 2018 Analysis Comparing AVERT Uniform EE Factors to AVERT-Generated CHP Emissions Factors
CHP 24/7
CHP
AVERT Region
Uniform EE
Base load
Commercial
Northeast
1,231
1,201
1,226
Great Lakes/Mid-Atlantic
1,903
1,832
1,829
Southeast
1,630
1,613
1,619
Lower Midwest
1,897
1,857
1,835
Upper Midwest
2,013
1,971
1,944
Rocky Mountains
1,998
1,852
1,789
Texas
1,498
1,498
1,509
Southwest
1,354
1,306
1,290
Northwest
1,691
1,622
1,644
California
1,148
1,112
1,119
Table B-2 summarizes the latest uniform EE emissions factors for C02, NOx, S02, and PM2.5 in all AVERT regions.
33
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Table B-2: 2019 AVERT Uniform EE Emissions Factors (Ib/MWh)
AVERT Subregion
Avoided C02
Rate
Avoided NOx
Rate
Avoided S02
Rate
Avoided
PM 2.5 Rate
National
1,550
0.85
0.92
0.11
California
1,061
0.27
0.06
0.04
Carolinas
1,664
1.00
0.64
0.12
Central
1,800
1.29
1.36
0.08
Florida
1,087
0.35
0.23
0.08
Mid-Atlantic
1,540
0.73
1.18
0.13
Midwest
1,860
1.26
1.67
0.16
New England
1,104
0.20
0.09
0.03
New York
1,090
0.36
0.17
0.05
Northwest
1,636
1.15
0.75
0.09
Rocky Mountains
1,904
1.05
0.58
0.04
Southeast
1,563
0.83
0.34
0.09
Southwest
1,544
0.95
0.29
0.08
Tennessee
1,479
0.56
0.74
0.10
Texas
1,282
0.54
0.65
0.06
B.4 EPA's Emissions & Generation Resource Integrated Database (eGRID)
EPA's eGRID28 provides an emission profile of almost all grid-connected power plants in the United States. The
data is provided at the combustion unit and generator levels and then combined at the plant level. The plant
level data are then aggregated to state, U.S. total, and three types of power grid regions: balancing authority
area (generally smaller regions of the power grid in which all power plants are managed to balance power
system demand and supply); eGRID subregion; and NERC region, as designated by the North American Electric
Reliability Corporation (plus Alaska, Hawaii, and Puerto Rico).
28 EPA has generated and published detailed information on electricity generation and emissions since 1998. The most recent edition of eGRID
was released in 2021 and contains data collected in 2019. More information is available at https://www.epa.eov/eerid.
34
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eGRID data is based on data from the DOE's Energy Information Administration (EIA) Forms EIA-860 and EIA-
923, and EPA's Power Sector Emissions Data. Emission data from EPA is integrated with generation data from
EIA to produce data in pounds of emissions per megawatt-hour of electricity generation (Ib/MWh) that allow
direct comparison of the environmental attributes of electricity generatione. GRID provides data on generation
(MWh), fuel use, plant heat rate, resource mix (e.g., generation from coal, gas, nuclear, wind, solar), and
emissions associated with power generation in the U.S. eGRID consists of historic sets of recent data; it does
not include future projections of the operating characteristics of generating units. The generation data and
related data categories provided by eGRID are based on generated electricity, not consumed (i.e., delivered)
electricity and therefore do not include the impact of transmission and distribution (T&D) losses (see Section
3.1.2 and Equation 5 for more information on T&D losses).
The eGRID data is aggregated to a subregion level based on NERC regions, balancing authorities, and
transmission systems. There are 27 eGRID subregions (see Figure B-6) in eGRID2019. eGRID subregions
generally represent sections of the grid that have similar resource mix and emissions characteristics.
35
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Figure B-6: eGRID Subregion Map29
Map of eGRID Subregions
USEPA, eGRID, February 2021
Crosshatttwg indicates that an area falls *v
>1 w SRf
# erct
Alaska
AKMS
-jk\
AKGD
Hawaii
HI OA
HIMS
Puerto Rico
PRMS
Emissions and Heat Rate Data30
eGRID presents the heat rate of each listed plant, and emissions data aggregated by fuel type and by generation
source category (e.g., all fossil fuels). eGRID also presents emissions data for several pollutants—carbon dioxide
(CO2), nitrogen oxides (NOx), sulfur dioxide (SO2), methane (CKU), nitrous oxide (N2O) and mercury (Hg)—in the
form of emissions rates on an electricity output basis (Ib/MWh) and on a fuel input basis (Ib/MMBtu).
29 Many of the boundaries shown on this map are approximate because they are based on transmission systems rather than on strict
geographical boundaries,
30 Notes on Terminology. For the sake of clarity and consistency, eGRID emission rates (Ib/MWh) are referred to in this appendix as emissions
factors. Also note that, because this document addresses how to calculate avoided C02 emissions, all subsequent references to eGRID emissions
data in this appendix refer to C02 emissions only.
36
-------
Three types of eGRID generation rates are discussed in this appendix31:
• Total Output
The Total Output rates are based on data for all power generation regardless of energy source (i.e.,
fossil, nuclear, hydro, and renewables) within a defined region or subregion. One CO2 emissions factor
(Ib/MWh) and one heat rate (Btu/kWh) value are associated with each region or subregion.
• Fossil Fuel Output
The Fossil Fuel Output rates are based on data for power generation from fossil fuel-fired plants within
a defined region or subregion. One CO2 emissions factor (Ib/MWh) and one heat rate (Btu/kWh) value
are associated with the category for each region or subregion. EPA characterizes this emissions factor
as "an estimate to determine how much emissions could be avoided if energy efficiency and/or
renewable energy displaces fossil fuel generation."32 The EPA CHP Partnership recommends the
emissions factor and heat rate from this category to determine emissions and fuel use from displaced
grid electricity when evaluating CHP systems.33
• Non-baseload Output
The term "baseload" refers to generating plants that supply electricity to the grid even when demand
for electricity is relatively low. Baseload plants are usually brought online to provide electricity to the
grid regardless of the level of demand and they generally operate continuously except when
undergoing routine or unscheduled maintenance.
eGRID calculates non-baseload factors by weighting each plant's emissions and generation according
to its capacity factor (a plant's annual generation divided by its potential annual generation at full
capacity). The generation and emissions from plants that operate most of the time (that is, baseload
plants with annual capacity factors greater than 0.8) are excluded. All the generation and emissions
from fuel-based plants that operate infrequently during the year (for example, peaking units with
capacity factors less than 0.2) are included. A portion of the emissions and generation from the
remaining fuel-based plants (i.e., those with capacity factors between 0.2 and 0.8) are included, with
higher portions used for plants with lower capacity factors and lower portions used for plants with
higher capacity factors.
eGRID also provides emissions factors by specific fossil fuel type (i.e., for coal-, natural gas-, and oil-fired
generating plants). These emissions factors are useful in assessing the different impacts of fossil fuels but they
are rarely used to evaluate the relationship between CHP and displaced grid electricity emissions. Table B-3
provides the latest 'all generation', 'all fossil', and 'non-baseload' emissions factors from eGRID.
31 In addition to the three eGRID generation categories listed here, eGRID also includes an "annual combustion output" category. This category
is not discussed in this appendix since it was primarily developed to estimate NOx and SO2 emissions from combustion generating units that are
dispatched to respond to marginal increases in electricity demand, and thus not applicable to C02 calculations involving CHP.
32 EPA eGRID Technical Support Document. February 2021. https://www.epa.eov/eerid/eerid-technical-support-document
33 The CEESC is available at:https://www.epa.eov/chp/chp-enerev-and-emissions-savines-calculator
37
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Selecting the Appropriate eGRID Aggregation Level
When selecting the appropriate grid electricity emissions factor (EFg) and heat rate (HRg) required by
Equations 6 and 7 in Section 3.1.2, the aggregation level is based on the electricity supplied to the site
where the CHP system is located. The Partnership therefore recommends using the eGRID emissions
factor and heat rate for the eGRID subregion where the CHP system is located. The Partnership bases
this recommendation on the following factors:34
• In general, eGRID subregions represent sections of the grid that have similar resource mix and
emissions characteristics, operate as an integrated entity, and support most of the demand in
the subregion with power generated within the subregion.
• State-level aggregation omits generation that is imported into the state and does not account
for generation that is exported to other states. State-level aggregation is no longer provided
as an option in the CEESC.
• Emissions factors and heat rates by aggregated by NERC region (or the U.S. average) do not
reflect significant regional variations in emissions from generation and therefore do not
accurately reflect the fuel use and emissions impacts of generation displaced by a specific CHP
system.
Selecting the Appropriate eGRID Emissions and Heat Rate Category
When selecting the eGRID emissions and heat rate category, it is important to select the category that
contains generator level data representative of those that are displaced by CHP systems. At first
glance, each of the eGRID categories mentioned above (i.e., total output, fossil fuel output, and non-
baseload) may seem like reasonable choices for HRg in Equation 6 and EFg in Equation 7 of Section
3.1.2; however, the Partnership recommends using the following factors:
• the eGRID fossil fuel output emissions factor and heat rate for the eGRID subregion where the
CHP system is located for baseload CHP (i.e., greater than 6,500 annual operating hours), and
• the eGRID non-baseload emissions factor and heat rate for the eGRID subregion where the
CHP system is located for CHP systems with relatively low annual capacity factors (i.e., less
than 6,500 annual operating hours) and with most generation occurring during periods of high
system demand.
Estimating the energy and emissions displaced by CHP requires an estimate of the nature of generation
displaced using power produced by the CHP system. Accurate estimates can be made using a power
system dispatch model to determine how emissions for generation in a specific eGRID subregion are
impacted by the shift in the system demand curve and generation mix resulting from the addition of
CHP systems. However, these models are complex and costly to run.
34 Rothschild, S. et al., "The Value of eGRID and eGRIDweb to GHG Inventories", https://www.epa.gov/sites/production/files/2015-
12/documents/thevalueofegrid.pdf
38
-------
Table B-3: eGRID Ninth Edition C02 Emissions factors and Heat Rates by NERC Region and eGRID Subregion (2019-year data)
All Generation
All Fossil Average
Non-Baseload
NERC Region and Subregions
Heat Rate
C02 Emission
Heat Rate
C02 Emission
Heat Rate
C02 Emission
(Btu/kWh)
Factor (Ib/MWh)
(Btu/kWh)
Factor (Ib/MWh)
(Btu/kWh)
Factor (Ib/MWh)
Alaska Systems Coordinating Council
6,738
1,008
9,682
1,448
9,526
1,424
ASCC Alaska Grid
7,848
1,114
9,428
1,353
9,287
1,333
ASCC Miscellaneous
3,646
549
10,141
1,526
10,102
1,520
FRCC All
6,677
861
7,629
1,005
7,812
1,030
Hawaiian Islands Coordinating Council
9,800
1,605
10,134
1,743
9,814
1,688
HICC Miscellaneous
8,058
1,186
10,253
1,686
9,421
1,549
HICC Oahu
10,192
1,695
10,097
1,761
9,770
1,704
Midwest Reliability Organization
5,790
1,034
9,789
1,770
9,462
1,710
MRO East
8,490
1,503
9,676
1,775
8,600
1,578
MRO West
5,647
1,098
10,030
1,977
9,165
1,807
Northeast Power Coordinating Council
3,852
425
7,462
893
7,766
929
NPCC Long Island
10,209
1,209
9,385
1,130
10,802
1,301
NPCC New England
4,627
489
7,050
841
7,043
840
NPCC NYC/Westchester
4,665
554
7,640
910
8,536
1,016
NPCC Upstate NY
2,088
232
7,163
865
7,372
890
PR - Puerto Rico
9,893
1,537
10,131
1,574
10,219
1,588
PRMS- Puerto Rico Miscillaneous
9,893
1,537
10,131
1,574
10,219
1,588
Reliability First Corporation
5,851
965
8,877
1,490
9,869
1,657
RFC East
4,918
695
8,012
1,155
8,585
1,238
RFC Michigan
7,033
1,189
9,046
1,577
10,138
1,767
RFC West
6,092
1,068
9,324
1,653
10,334
1,832
39
-------
All Generation
All Fossil Average
Non-Baseload
NERC Region and Subregions
Heat Rate
C02 Emission
Heat Rate
C02 Emission
Heat Rate
C02 Emission
(Btu/kWh)
Factor (Ib/MWh)
(Btu/kWh)
Factor (Ib/MWh)
(Btu/kWh)
Factor (Ib/MWh)
Southeast Reliability Corporation
6,025
912
8,470
1,317
8,542
1,328
SERC Midwest
7,989
1,584
10,045
1,996
9,869
1,961
SERC Mississippi Valley
5,919
807
7,858
1,099
8,584
1,200
SERC South
6,556
969
8,572
1,315
9,061
1,390
SERC Tennessee Valley
5,493
950
9,197
1,603
8,978
1,565
SERC Virginia/Carolina
4,708
675
8,320
1,248
8,995
1,349
SPP North
5,579
1,070
10,137
1,949
10,190
1,959
SPP South
6,537
1,002
9,494
1,473
9,952
1,544
Texas Regional Entity
5,821
870
8,275
1,243
8,539
1,283
TRE All
5,827
869
8,262
1,238
8,521
1,277
Western Electricity Coordinating Council
4,912
769
9,001
1,450
8,567
1,380
WECC California
3,876
453
7,461
941
7,642
964
WECC Northwest
4,209
715
9,491
1,651
9,295
1,617
WECC Rockies
6,949
1,243
10,020
1,800
8,791
1,579
WECC Southwest
6,162
952
9,041
1,407
9,285
1,445
40
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As stated previously, eGRID provides two rates that can be used to estimate the mix of generation that is
displaced using clean energy technologies such as CHP: the fossil fuel output rates and the non-baseload output
rates. Use of the total output rates is not appropriate since it includes a substantial amount of baseload
generation that is not offset by CHP projects.
Figures B-7 and B-8 show the eGRID fossil fuel and non-baseload resources mapped onto the hypothetical load
duration curve. The fossil fuel resources contain a large amount of combined cycle and coal plants that primarily
produce baseload power.
Figure B-7: eGRID Fossil Fuel Resources Mapped onto Hypothetical Load Curve
10000
9000
8000
7000
5 6000
>
ra 5000
Q.
ro
U
"O
is 4000
3000
2000
1000
Gas and Oil Peaking
Gas and Oil Intermediate
eGRID Fossil Fuel Resources
Combined Cycle Gas
and Coal
Wind and Solar
Nuclear and Hydro
1000
2000
3000
4000 5000
Hours/year
6000
7000
8000
Figure B-8 shows an approximation of the eGRID non-baseload resources. This curve more closely represents
displaced grid emissions from CHP systems that are primarily operating during peak day and evening hours,
typically around 5,000 hours/year.
41
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Figure B-8: eGRID Fossil Fuel Resources Mapped onto Hypothetical Load Curve
10000
9000
7000
6000
id 4000
3000
2000
1000
Gas and Oil Peaking
es°urces
Gas and Oil Intermediate
Combined Cycle Gas
and Coal
Wind and Solar
Nuclear and Hydro
1000
2000
3000
4000 5000
Hours/year
6000
7000
8000
B.5 Recommendations
CEESC users have the option to select either AVERT or eGRID emissions factors. For the purpose of the CEESC,
the differences between AVERT and eGRID emission factors do not result in a significant difference in the final
estimate. There are variations for a few regional levels. Some AVERT regions map with multiple eGRID
subregions and for a CHP system located in this regions, a user will see variations in generation sources and
associated emission factors. The key differences between eGRID and AVERT emissions factors, and how they
are used in the CEESC, are summarized in Table B-4.
42
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Table B-4: Comparison of eGRID and AVERT Emissions Factors for Estimating CHP Energy and Emissions
Savings with CEESC
Tool Characteristics
eGRID
AVERT
Regions
27 subregions including Alaska,
Hawaii, and Puerto Rico
14 regions, continental United
States
Emissions Factors Used
Fossil Fuel or Non-Baseload
Uniform EE
T&D Losses
Select from menu of options
Included in AVERT factors
Heat Rate
Included for both factors
Estimated using eGRID subregion
heat rates
Pollutants
NOx, SO2, CO2, CH4, n2o
NOx, SO2, CO2 (others estimated with
eGRID data)
The Partnership compared the difference in emissions factors and associated grid emission estimates between
eGRID2019 factors (2019 data with T&D losses added) and 2020 AVERT factors (2019 data with T&D losses built
in). The analysis showed that while there are some regional differences, the three factors - eGRID All Fossil,
eGRID Non-Baseload, and AVERT Uniform EE - all track relatively close to each other on average across the U.S.
Table B-5 shows a comparison of AVERT and eGRID carbon emission factors, both using 2019 data.
Both AVERT and eGRID emission factors provide estimates for displaced grid emissions that can be used to help
approximate the energy and emissions savings associated with CHP installations.
CEESC users are recommended to use AVERT factors by default, as they use a more rigorous and sophisticated
method of estimating marginal displaced grid emissions. However, for end users that meet the following criteria,
eGRID may be the preferred option:
• Heat rate information is desired for energy savings calculations (heat rate data is tied to eGRID
subregions).
• Grid emissions data for CH4 and N20 is desired (found in eGRID, used in calculating C02-equivalent
emissions).
• End user is located in one of four AVERTs region that corresponds to multiple eGRID subregions: Central
and Mid-Atlantic that have two corresponding eGRID subregions, and Midwest and New York that have
three corresponding eGRID subregions.
• End user is located in Alaska, Hawaii, or Puerto Rico.
43
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Table B-5. Comparison of AVERT Uniform EE Factors with Corresponding eGRID Subregion Factors
eGRID 2019 with T&D losses (Ib/MWh C02)
AVERT Emission Factors
(Ib/MWh C02, 2019)
eGRID2019 Subregion Match eGRID2019 Subregion Match
(if more than 1 eGRID subregion)
eGRID2019 Subregion Match
(if more than 2 eGRID subregion)
Uniform eGRID Fossil- Non- eGRID Fossil- Non- eGRID Fossil- Non-
EE subregion Fired baseload subregion Fired baseload subregion Fired baseload
California
1,061
CAMX
992
1,016
-
-
-
-
-
-
Carolinas
1,664
SRVC
1,319
1,426
-
-
-
-
-
-
Central
1,800
SPNO
2,060
2,070
SPSO
1,473
1,544
-
-
-
Florida
1,087
FRCC
1,063
1,088
-
-
-
-
-
-
Mid-Atlantic
1,540
RFCE
1,221
1,309
RFCW
1,653
1,832
-
-
-
Midwest
1,860
SRMW
2,110
2,073
MROW
1,977
1,807
SRMV
1,099
1,200
New England
1,104
NEWE
889
888
-
-
-
-
-
-
New York
1,090
NYUP
914
941
NYLI
1,130
1,301
NYCW
910
1,016
Northwest
1,636
NWPP
1,746
1,710
-
-
-
-
-
-
Rocky Mountains
1,904
RMPA
1,896
1,664
-
-
-
-
-
-
Southeast
1,563
SRSO
1,390
1,469
-
-
-
-
-
-
Southwest
1,544
AZNM
1,483
1,523
-
-
-
-
-
-
Tennessee
1,479
SRTV
1,695
1,655
-
-
-
-
-
-
Texas
1,282
ERCT
1,305
1,346
-
-
-
-
-
-
U.S. Average
1,558
U.S. Average
1,476
1,497
-
-
-
-
-
-
44
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