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2022 Green-e® Residual Mix Emissions Rates (2020 Data)

Released July 19, 2022

 

The information in this table can be used to calculate the greenhouse gas (GHG) emissions associated with untracked and unclaimed  U.S.-based sources of electricity, based on location of consumption. The table provides the “Green-e® residual mix emissions rate,” an emissions rate that is adjusted to remove all Green-e® Energy certified sales for each Emissions & Generation Resource Integrated Database (eGRID) subregion [1] (see eGrid subregion map).

Green-e® residual mix emissions rates are published every Spring using Green-e® voluntary renewable energy market sales data collected during the annual Green-e® verification audit from two calendar years prior and the most recent U.S. generation and emissions rate at the time of publication. It does not include any data that is not reported to Green-e. The residual mix emissions rate used should be based on the eGRID subregion in which the electricity is consumed. Individuals can figure out which eGRID subregion in which they are located by using the EPA’s Power Profiler tool.

 

Scope 2 Reporting

When calculating the emissions from unspecified purchased or acquired electricity (considered “Scope 2” emissions, as defined by the World Resources Institute [WRI]), where more-accurate information about the resources and emissions associated with electricity use is not available from the user’s state, region, or electricity supplier, residual mix emissions rates should be used. Regional residual mix emissions rates that factor out all specified electricity purchases are not yet available for all regions of the U.S. or published by a national data source. Until such time, Green-e® residual mixes are available, which factor out all Green-e® certified sales of renewable energy. Users reporting their GHG data should cite the use of these residual mix rates in their accounting. Use of these numbers is compatible with WRI’s Greenhouse Gas Protocol Scope 2 Guidance,[2] which defines residual mix in more detail. Green-e® Energy also offers the Green-e® Energy Summary of WRI Scope 2 Guidance, a guide for purchasers of Green-e® Energy certified renewable energy on how to calculate Scope 2 emissions.[3]

 

Residual Mix Rate Calculation Methodology

This table shows the residual mix calculation based on eGRID subregions. These rates were calculated using the data collected by Green-e® Energy during annual verification of 2020 certified sales and the 2020 emissions and generation data provided by eGRID in the U.S. for each eGRID subregion[4] in the U.S. for each eGRID subregion.

The residual mix emissions rate is calculated by first subtracting all unique Green-e® Energy certified sales[5] (in megawatt-hours [MWh]) from the total generation within each subregion. The total CO2 emissions for each region are then divided by this new generation number for each subregion, resulting in an adjusted emissions rate (lb CO2/MWh) that accounts for use of renewable energy from a Green-e® Energy certified product.

For this calculation, each U.S.-generated MWh is assigned to a specific eGRID subregion, with generating facilities assigned to eGRID subregions using facility zip codes and Energy Information Agency data. Generation from facilities that cannot be readily assigned to eGRID subregions is excluded from these residual mix emissions rates.

 

2022 Green-e® Residual Mix Emission Rates
(2020 Data)

 

eGrid Subregion CO2 Emissions (tons) Net Generation (MWh) Emission Rate (lb / MWh) Voluntary RE emissions (lbs) Voluntary RE (MWh) Adjusted System Mix (lbs / MWh) Difference (lbs / MWh) % Difference
AKGD 2,557,432 4,659,917 1,097.63 0 38,286 1,106.72 9.09 0.83%
AKMS 399,522 1,496,130 534.073 0 0 534.07 0.00 0.00%
AZNM 70,012,956 165,394,893 846.616 0 286,306 848.08 1.47 0.17%
CAMX 50,351,935 196,129,978 513.455 0 4,073,260 524.34 10.89 2.12%
ERCT 169,823,316 414,911,396 818.6 0 37,282,249 899.42 80.82 9.87%
FRCC 100,795,433 241,403,268 835.079 0 1,104,432 838.92 3.84 0.46%
HIMS 1,400,759 2,450,535 1,143.23 0 0 1,143.23 0.00 0.00%
HIOA 5,470,199 6,618,705 1,652.95 0 0 1,652.95 0.00 0.00%
MROE 15,809,335 20,714,885 1,526.37 0 60,000 1,530.81 4.43 0.29%
MROW 111,236,072 227,120,021 979.54 0 12,466,067 1,036.42 56.89 5.81%
NEWE 25,565,657 96,795,891 528.238 0 55,524 528.54 0.30 0.06%
NWPP 85,796,739 286,004,986 599.967 0 7,444,759 616.00 16.03 2.67%
NYCW 12,605,747 39,727,442 634.612 0 0 634.61 0.00 0.00%
NYLI 6,356,304 10,559,287 1,203.93 0 0 1,203.93 0.00 0.00%
NYUP 9,883,912 84,654,342 233.512 0 22,169 233.57 0.06 0.03%
PRMS 14,592,590 18,215,878 1,602.18 0 2,643 1,602.42 0.23 0.01%
RFCE 92,572,477 283,765,353 652.458 0 55,661 652.59 0.13 0.02%
RFCM 49,192,807 85,325,787 1,153.06 0 143,392 1,155.00 1.94 0.17%
RFCW 244,476,328 496,410,171 984.98 0 887,975 986.74 1.77 0.18%
RMPA 36,670,878 64,065,081 1,144.80 0 803,356 1,159.34 14.54 1.27%
SPNO 33,399,418 70,017,393 954.03 0 6,416,416 1,050.28 96.25 10.09%
SPSO 70,948,081 152,288,973 931.76 0 20,987,972 1,080.69 148.94 15.98%
SRMV 59,226,139 159,992,962 740.359 0 579,320 743.05 2.69 0.36%
SRMW 80,432,435 108,641,153 1,480.70 0 1,132,412 1,496.30 15.60 1.05%
SRSO 105,866,752 246,150,586 860.179 0 1,537,067 865.58 5.40 0.63%
SRTV 88,231,707 211,540,764 834.182 0 61,117 834.42 0.24 0.03%
SRVC 101,720,864 326,493,675 623.111 0 2,060,767 627.07 3.96 0.64%

 

 

[1] eGRID subregions are identified and defined by EPA and were developed as a compromise between NERC regions (which EPA felt were too big) and balancing authorities (which EPA felt were generally too small). Using NERC regions and balancing authorities as a guide, the subregions were defined to limit the import and export of electricity in order to establish an aggregated area where the determined emission rates most accurately matched the generation and emissions from the plants within that subregion.

[3] The Green-e® Energy Summary of WRI Scope 2 Guidance is available at https://www.green-e.org/docs/energy/Scope2Summary.pdf

[4] U.S. EPA's Emissions & Generation Resource Integrated Database (eGRID). eGRID2020 (released 01/17/2022) contains the complete release of year 2020 data, https://www.epa.gov/energy/emissions-generation-resource-integrated-database-egrid.

[5] Unique Green-e® Energy certified sales remove any MWh associated with a Green-e® Energy certified retail sale for which the supply was purchased via a Green-e® Energy certified wholesale transaction, since these two sales represent the same MWh of generation.