Source: National Renewable Energy Laboratory (NREL).

The figures below correspond with the biogas potential map scale, and they are measured in tons of methane emissions per year, by state.

Within each state map, each county is color-coded based on the following scale. The figures represent the total tons of methane emissions per year, by county.

NREL's biogas potential was calculated by considering the following animal types: dairy cows, beef cows, hogs and pigs, sheep, chickens (layers and broilers) and turkey. The data on animal population by county was obtained from the 2002 USDA National Agricultural Statistics. All emissions were calculated by animal type and manure management system.

Source: United States Environmental Protection Agency's AgSTAR Program.

The accuracy of these data cannot be guaranteed by AgSTAR. The economic and environmental benefits of biodigesters suggest that new biodigestor projects are most effective at existing feedlot operations.