National carbon intensity fell18 percent between 2016 and 2020, but great variance remains

A new report from the U.S. Energy Information Administration (EIA) revealed that the carbon intensity throughout the nation fell by as much as 18 percent between 2016-2020, bolstered by shifts toward natural gas and renewables usage.

Carbon intensity refers to measures of the amount of CO2 emitted to produce a unit of electricity. In 2020, that figure averaged 854 pounds of CO2 per MW hour, but with that comes some variance and caveats. For one thing, intensity varied by energy source. That same year, coal’s carbon intensity was 2,274 pounds of CO2/MWh, while natural gas was comparatively lower, at 980 pounds of CO2/MWh. Renewables, though, saw little to no CO2 emissions.

Second, carbon intensity also varied by state. All but seven states in the five-year (2016-2020) period reduced carbon intensity. The five states with the largest reductions in carbon intensity were Tennessee (486 pounds of CO2/MWh), Maryland (477 pounds of CO2/MWh), Iowa (443 pounds of CO2/MWh), Kansas (371 pounds of CO2/MWh) and Oklahoma (348 pounds of CO2/MWh). However, Vermont had the lowest carbon intensity of all states, with just 8.4 pounds of CO2/MWh, since nearly all of its in-state generation came from renewables and most of its electricity – approximately 60 percent – is imported from Canada.

Additionally, states receive and deliver electricity to other states – and countries – so the carbon intensity of a state’s generation does not genuinely reflect the carbon intensity used within a state. That said, Wyoming hosted the highest carbon intensity in 2020, as it produced 79 percent of its power from coal, leading to figures of 1,970.8 pounds of CO2/MWh.