How many eGRID subregions are there?

There are 27 eGRID subregions in eGRID2023 Rev 2, covering the contiguous US, Alaska, Hawaii, and Puerto Rico. Each subregion has different emission rates based on its local generation mix.

What is the cleanest eGRID subregion?

NYUP (Upstate New York) has the lowest CO₂e emission rate at 242.8 lb/MWh (0.110 kg/kWh), due to its high share of hydropower (33%) and nuclear (32%).

What is the dirtiest eGRID subregion?

PRMS (Puerto Rico) has the highest CO₂e emission rate at 1,548.5 lb/MWh (0.702 kg/kWh), because 83% of its electricity comes from oil and gas.

← emission-factors.com

All 27 eGRID Subregion Emission Factors

EPA eGRID2023 Rev 2 (released June 12, 2025) · Sorted by CO₂e, cleanest first

The EPA divides the US electricity grid into 27 subregions, each with different generation mixes and emission intensities. The table below shows the output emission rate for each subregion - the primary factor used for GHG Protocol Scope 2 location-based carbon accounting.

New: eGRID2024 (Cornerstone run of EPA's code) is now available via the API. Add ?year=2024 to any lookup request for eGRID2024 emission factors (Cornerstone). Average change vs. 2023: -1.8% CO2e. Notable shifts: NYUP +12.3%, SPNO -9.6%, NWPP -8.3%, CAMX -5.8%. Source: Cornerstone Data (CC-BY-4.0), generated from EPA's open-source eGRID R pipeline. Default remains eGRID2023 Rev 2 below.

Need this data programmatically? The Emission Factors API returns these factors by ZIP code - including the ZIP-to-subregion mapping that the EPA doesn't publish as an API. Read the API docs - free, no key, no signup.

Subregion	CO₂e (lb/MWh)	CO₂e (kg/kWh)	Carbon-free	Renewable	Top fuel sources
NYUP	242.8	0.1101	74.1%	41.8%	hydro 33%, nuclear 32%, gas 26%
CAMX	430.0	0.1950	54.3%	46.4%	gas 43%, solar 20%, hydro 14%
AKMS	522.4	0.2370	68.9%	68.9%	hydro 67%, oil 25%, gas 6%
NEWE	543.2	0.2464	41.8%	19.2%	gas 56%, nuclear 23%, hydro 8%
SRVC	596.3	0.2705	49.8%	9.9%	nuclear 40%, gas 39%, coal 10%
RFCE	599.2	0.2718	40.4%	4.0%	gas 54%, nuclear 36%, coal 5%
NWPP	635.3	0.2882	58.2%	55.1%	hydro 39%, gas 25%, coal 16%
AZNM	706.2	0.3203	40.2%	22.3%	gas 49%, nuclear 18%, coal 11%
ERCT	736.6	0.3341	37.2%	28.7%	gas 50%, wind 23%, coal 13%
SRMV	741.7	0.3364	25.1%	3.0%	gas 65%, nuclear 22%, coal 8%
FRCC	784.8	0.3560	18.6%	6.6%	gas 75%, nuclear 12%, solar 5%
SRSO	846.0	0.3837	29.9%	9.5%	gas 55%, nuclear 20%, coal 15%
NYCW	865.7	0.3927	0.6%	0.6%	gas 98%, other fossil 1%, oil 1%
SPNO	867.7	0.3936	54.2%	40.1%	wind 40%, coal 32%, gas 14%
SPSO	875.6	0.3972	36.8%	36.8%	gas 46%, wind 33%, coal 16%
SRTV	903.3	0.4097	41.9%	9.1%	nuclear 33%, gas 30%, coal 28%
AKGD	905.1	0.4106	16.3%	16.3%	gas 60%, coal 14%, hydro 14%
RFCW	916.1	0.4155	36.0%	7.6%	gas 38%, nuclear 28%, coal 25%
MROW	926.6	0.4203	51.3%	43.5%	wind 38%, coal 35%, gas 13%
RFCM	976.0	0.4427	21.3%	11.2%	gas 50%, coal 26%, nuclear 10%
RMPA	1042.5	0.4729	41.9%	41.9%	coal 32%, gas 26%, wind 26%
HIMS	1133.3	0.5141	34.2%	34.2%	oil 66%, wind 12%, geothermal 7%
NYLI	1189.3	0.5395	6.5%	6.5%	gas 87%, other fossil 5%, biomass 4%
SRMW	1248.6	0.5663	31.6%	15.2%	coal 51%, gas 17%, nuclear 16%
MROE	1405.0	0.6373	17.3%	17.3%	gas 43%, coal 39%, wind 5%
HIOA	1498.9	0.6799	14.2%	14.2%	oil 83%, solar 7%, wind 4%
PRMS	1548.5	0.7024	2.3%	2.3%	gas 44%, oil 39%, coal 15%

Get this data by ZIP code, not just by subregion. Free API - no key, no signup.

Read the API docs →

How to read this table

CO₂e (lb/MWh) - the EPA's native unit. Total CO₂-equivalent output emission rate per megawatt-hour of electricity generated.
CO₂e (kg/kWh) - converted for international/metric use. Formula: lb/MWh × 0.45359237 / 1000.
Carbon-free % - nuclear plus EPA's total renewables (hydro, wind, solar, geothermal and biomass), as a share of generation.
Renewable % - share from renewable sources only (excludes nuclear).
Color coding - green (<0.25 kg/kWh), black (0.25–0.33), orange (0.33–0.44), red (>0.44 kg/kWh).

About this data

Source: EPA eGRID2023 Rev 2, Table 1: eGRID Subregion Output Emission Rates. Released June 12, 2025. This is the most recent official EPA edition. eGRID2024 factors (Cornerstone run of EPA's code) are available via the API with ?year=2024 (source: Cornerstone Data, CC-BY-4.0).

The emission rates represent the output emission rate - emissions per unit of electricity delivered to the grid. This is the factor recommended by the GHG Protocol Scope 2 Guidance for location-based accounting.

Mapping ZIP codes to subregions

The EPA publishes factors by subregion, not by ZIP code. To look up a specific address, you need a mapping from ZIP codes (specifically Census ZCTAs) to eGRID subregions. This API builds one by placing each ZCTA's area centroid in EPA's eGRID2023 subregion boundaries.

Our API handles this mapping for 33,700+ US ZCTAs (99.9% of Census ZCTAs), including Puerto Rico (PRMS). Each ZIP gets the one subregion containing its centroid. PO-box ZIPs have no ZCTA and return no subregion, and the territories outside eGRID (Guam, American Samoa, the Northern Mariana Islands, the US Virgin Islands) return a note saying so.

Query emission factors by ZIP code, coordinates, or in bulk. See the API docs.

Try it now →

emission-factors.com is an independent service. Not affiliated with the EPA. Terms · Privacy