This article outlines electricity grid emissions factors used from the US Environmental Protection Agency (EPA) Emission Factors for Greenhouse Gas Inventories.
The US EPA factors are used by companies for US grid-level electricity emissions calculations and can be applied for the location-based electricity accounting approach only.
These factors account for scope 2 emissions as well as scope 3 emissions from upstream line losses.
The factors are derived from the following information sources:
- The US EPA’s GHG emissions factors hub which provides scope 2 emissions factors broken down by CO2, CH4 and N2O.
- The Intergovernmental Panel on Climate Change (IPCC) sixth assessment report which provides Global Warming Potentials (GWPs) for CO2, CH4 and N2O. The GWP for CO2 is 1, CH4 is 29.8 and the GWP for N2O is 273. These are used to convert the US EPA scope 2 emissions factors into lb (or pounds) CO2-equiavlents / kWh.
- The US EPA’s eGRID summary data which provides grid loss factors to calculate scope 3 emission factors using sources #1 and #2 above.
These emissions factors are available for use across the US eGrid subregions.
The eGRID subregions are a system developed by the EPA to provide more specific regional and accurate estimates of greenhouse gas emissions from electricity generation.
A map of the subregions can be found here.