2023 Residual Mix Emissions Rates (2021 Data)

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]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 … Continue reading (see eGrid subregion map).

Green-e® residual mix emissions rates are published each year using Green-e® Energy voluntary renewable energy market sales data collected during the annual Green-e® Energy 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 through the Green-e® Energy verification process. 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® Energy 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]Available at www.wri.org/research/ghg-protocol-scope-2-guidance. 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]The Green-e® Energy Summary of WRI Scope 2 Guidance is available at Green-e® Scope 2 Summary

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 2021 certified sales and the 2021 emissions and generation data provided by eGRID in the U.S. for each eGRID subregion[4]U.S. EPA’s Emissions & Generation Resource Integrated Database (eGRID). eGRID2021 historical data (released 01/30/2023) can be found at https://www.epa.gov/egrid/historical-egrid-data.. Please Note, the residual mix calculation published in 2022 compared data from generation generated in calendar year 2020 and used in certified sales, with 2020 emissions and generation data provided by eGRID[5]2023 Green-e® Residual Mix Emissions Rates (2021 data) will be updated to be consistent with this methodology once the 2022 Green-e® Verification data is finalized..

The residual mix emissions rate is calculated by first subtracting all unique Green-e® Energy certified sales[6]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 … Continue reading (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.

2023 Green-e® Residual Mix Emission Rates (2021 Data)

 

eGrid Subregion CO2 Emissions (tons) Net Generation (MWh) Emission Rate (lb / MWh) Voluntary RE emissions (lbs) Voluntary RE (MWh) (12-month vintage) Adjusted System Mix (lbs / MWh) (12-month vintage) Difference (lbs / MWh) (12-month vintage) % Difference (12-month vintage)
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) Percentage Difference
AKGD 2,628,490 4,923,740 1,067.680 48247 1078.245753 10.566 0.99%
AKMS 405,635 1,672,078 485.186 485.1862744 0.000 0.00%
AZNM 68,844,906 167,984,970 819.656 184639 820.5574487 0.901 0.11%
CAMX 54,378,370 204,553,916 531.678 2345286.4 537.8442012 6.166 1.16%
ERCT 171,512,267 421,638,208 813.552 44039665.7 908.4371237 94.885 11.66%
FRCC 98,847,877 237,351,634 832.924 2714379 842.5591017 9.635 1.16%
HIMS 1,483,984 2,616,354 1,134.391 1134.391131 0.000 0.00%
HIOA 5,360,016 6,564,236 1,633.097 1633.096575 0.000 0.00%
MROE 19,076,416 24,114,781 1,582.135 1582.134707 0.000 0.00%
MROW 120,899,511 242,821,306 995.790 12227271.73 1048.59184 52.802 5.30%
NEWE 27,796,016 103,068,944 539.367 8524 539.4120379 0.045 0.01%
NWPP 89,737,301 282,815,849 634.599 8355871.768 653.9190308 19.320 3.04%
NYCW 13,272,151 32,499,681 816.756 816.7557808 0.000 0.00%
NYLI 7,228,121 11,938,038 1,210.940 1210.939504 0.000 0.00%
NYUP 9,964,947 85,506,174 233.081 16572 233.1265266 0.046 0.02%
PRMS 14,473,222 18,578,947 1,558.024 1558.023964 0.000 0.00%
RFCE 97,693,766 290,415,250 672.787 67778 672.9437992 0.157 0.02%
RFCM 57,324,577 94,434,454 1,214.061 155740.34 1216.066163 2.005 0.17%
RFCW 272,740,310 521,426,350 1,046.132 918398.581 1047.977497 1.845 0.18%
RMPA 38,267,892 66,044,054 1,158.860 1458599 1185.031267 26.171 2.26%
SPNO 36,381,645 73,370,171 991.729 10332344 1154.279793 162.551 16.39%
SPSO 76,753,129 148,803,953 1,031.601 27558536 1266.078855 234.478 22.73%
SRMV 66,170,857 171,263,642 772.737 736887.064 776.0759484 3.339 0.43%
SRMW 88,053,715 114,130,604 1,543.034 1865463 1568.674204 25.640 1.66%
SRSO 113,001,503 253,393,159 891.907 2285477.79 900.0242656 8.117 0.91%
SRTV 100,093,412 214,888,097 931.586 38568.496 931.7536118 0.168 0.02%
SRVC 103,410,187 323,326,029 639.665 2675448.401 645.002338 5.337 0.83%

References

References
↑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.
↑2 Available at www.wri.org/research/ghg-protocol-scope-2-guidance.
↑3 The Green-e® Energy Summary of WRI Scope 2 Guidance is available at Green-e® Scope 2 Summary
↑4 U.S. EPA’s Emissions & Generation Resource Integrated Database (eGRID). eGRID2021 historical data (released 01/30/2023) can be found at https://www.epa.gov/egrid/historical-egrid-data.
↑5 2023 Green-e® Residual Mix Emissions Rates (2021 data) will be updated to be consistent with this methodology once the 2022 Green-e® Verification data is finalized.
↑6 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.