eGRID & Green-e 2025 - methodology

Summary

Publisher	eGRID & Green-e
Full name	eGRID & Green-e
Description	Description: This database combines electricity emission factors from the U.S. EPA's eGRID database and the Green-e® Residual Mix Emissions Rates into a single, harmonized dataset for U.S. electricity reporting. eGRID provides the official location-based grid emission factors for nearly all electricity generated in the United States, while Green-e publishes residual mix factors for market-based Scope 2 reporting where no supplier-specific or contractual information is available. The combined dataset supports both the location-based and market-based accounting approaches defined by the GHG Protocol Scope 2 Guidance. It is intended for organizations reporting greenhouse gas emissions from purchased electricity across the United States using region-specific emission factors. Both underlying datasets are updated annually by their respective publishers
Version nr.	2025

Source documents

eGRID 2024 https://www.epa.gov/egrid/detailed-data
Green-e 2025 https://resource-solutions.org/2025-residual-mix/

Methodology readout notes

Emission factors are defined at the eGRID subregion level. This is the finest spatial granularity at which both location-based and residual market-mix data are available.

Each subregion has separate factors, taken from the following soures:

Location-based part is taken from eGRID (i.e., Output Emission Rates)
Market-based residual mix is taken from Green-e (i.e., Adjusted System Mix 12-month vintage)
Market-based green Contract is added as a 0 emission factor

Data considerations and notes

Greenhouse gas splits are available for eGRID factors and converted to CO₂-equivalents using IPCC AR6 GWP. Green-e factors contain only CO₂ data . For residual mix CO₂e calculations, CH₄ and N₂O factors are sourced from eGrid and combined with Green-e CO₂ values. This ensures consistency between location-based and market-based approaches.
T&D losses are taken from eGRID, which provides region-specific loss ratios and used for market-based and location-based factors
Generation losses are taken from IEA for the United States as a whole, and implemented as a fixed factor (i.e., 0,0568 kgCO₂e/kWh) for market-based and location-based factors