Over the last seven years, the electrical power sector has gone from being one of the most carbon-emitting sectors of the American economy per unit of fuel consumed to one of the least carbon-emitting sectors. That’s according to new data from the US Energy Information Administration (EIA). Despite the good news, the EIA’s numbers show that, since 1975, the carbon emissions of the US transportation sector per unit of fuel used has hardly changed at all.

The EIA measured relative emissions across the US economy as "carbon intensity"—an average of the amount of carbon any sector gives off as it consumes different kinds of fuel. The measurements were applied to five sectors of the US economy: transportation, commercial, residential, electric, and industrial.

The industrial sector is currently the least carbon intensive in its operations, and it gives off just 44 kilograms of CO 2 per million BTUs used. The EIA said part of this was due to the fact that several portions of the industrial sector run on biomass fuel. Although burning biomass releases carbon into the atmosphere, the EIA doesn’t count those emissions as energy-related CO 2 emissions because most kinds of biofuel absorb CO 2 from the atmosphere as growing plants. “The same consideration applies to the use of biogenic fuels in other sectors, such as wood heating in the residential sector and ethanol consumption in the transportation sector,” the EIA writes.

The electricity sector has shown the most change in the last decade, going from more than 60 kg of CO 2 per million BTUs used to just 48 kg of CO 2 . The EIA attributes this to increasing amounts of nuclear, wind, hydroelectric, and solar power used by the grid, which emit no CO 2 emissions.

Interestingly, the administration points out that the carbon intensity of the electric power sector using a million BTUs of fuel is now less than the carbon intensity of consuming a million BTUs of natural gas. “In other words, the combustion-weighted average of all fuels used to produce electricity in the United States (coal, natural gas, petroleum, nuclear, renewables) is now lower than the carbon intensity of natural gas.”

Unfortunately, the carbon intensity of the transportation sector has declined only a little since 1975, and it still remains the most polluting of all studied sectors of the US economy per unit of energy used. Although electric cars and buses have a dedicated contingent, they’ve yet to break through enough to put a major dent in the carbon intensity of that sector.

The EIA even breaks out the amount of electricity that each industry relies on (because production of electricity is counted in the analysis of the electrical power sector). Transportation’s curve barely changes.

Listing image by Arkansas Geological Survey