The EIA's Emissions Analysis by US States

In May, the US Energy Information Administration (EIA) released an analysis titled, State-Level Energy-Related Carbon Dioxide Emissions, According to the EIA’s assessment, between 2000 and 2010, CO2 emissions fell in 32 states and rose in 18 states. However, from 2009 to 2010, only 14 states saw a decrease in emissions. This increase is attributable to the fact that the US was emerging from recession. The greatest percentage decrease in CO2 emissions occurred in Delaware at 27.9 percent, (4.5 million metric tons). The greatest absolute decline was 58.8 million metric tons in Texas (8.3 percent). New York experienced a decline of 38.6 million metric tons (18.3 percent). The greatest percentage increase was in Nebraska at 16.0 percent (6.6 million metric tons), while Colorado experienced the greatest absolute increase (11.8 million metric tons or 13.9 percent).

A state’s emissions profile is largely determined by the types of fuels they use. Coal, petroleum and natural gas are the primary causes of CO2 emissions.

The differences in emission profiles are illustrated by a comparison of Vermont and Hawaii. In Vermont the largest share of emissions in 2010 came from the transportation sector (58.7 percent), predominantly from petroleum. Electric power sector has a low emissions profile (0.1 percent) because of Vermont’s reliance on nuclear power. However, because of the cold climate Vermont’s residential sector share was 22.1 percent because petroleum is the main heating fuel. Conversely in Hawaii the residential share is the lowest (0.3 percent) because of minimal heating and cooling requirements. Like Vermont, the transportation sector accounted for the largest share of emissions (49.3 percent). But unlike Vermont, Hawaii’s electric power sector share nearly as high (40.1 percent). The dominant fossil fuel for the generation of electricity in Hawaii is petroleum.

In terms of emissions per capita, 2010 CO2 emissions in Wyoming were 118.5 metric tons per capita, which is the highest in the U.S. In 2010, This is largely due to Wyoming relatively small population (less than 600 thousand people), low population density and cold climate. Wyoming is also the second largest energy producer in the US after Texas which does not fare as badly on the per capita metrics due to the state’s population of 25 million,

The state of New York, with a population of 19.6 million people, had the lowest per capita CO2 emissions—8.8 metric tons per capita largely due to the population density in New York City and an effective mass transit system. Further New York’s economy is oriented towards high-value, low-energy-consuming activities such as financial markets.

The carbon intensity of energy supply (CO2/Btu) is reflective of the energy fuel mix within a state. Sates with high carbon intensity of energy supply tend to be the states with high per capita emissions. The top five states in 2010 for the energy carbon intensity as measured in kilograms of CO2 per million Btu (kg CO2/MMBtu)—West Virginia (81.7 kg CO2/MMBtu), Kentucky (77.2 kg CO2/MMBtu), Wyoming (76.8 kg CO2/MMBtu), Indiana (75.1 kg CO2/MMBtu) and North Dakota (73.6 kg CO2/MMBtu)—are all states with coal as the dominant fuel.

The states with lower carbon intensity tend to be those states with relatively substantial non-carbon electricity generation such as hydropower or nuclear. These states include, for example, Vermont (34.5 kg CO2/MMBtu), Washington (37.4 kg CO2/MMBtu), Oregon (39.1 kg CO2/MMBtu), Idaho (41.2 kg CO2/MMBtu) and New Hampshire (41.5 kg CO2/MMBtu).

The states with the highest carbon intensity of their economies as measured in metric tons of CO2 per million dollars of state GDP (mt CO2/million dollars of GDP) are also the states with the highest values of energy intensity and carbon intensity of that energy supply. In 2010 these states included: Wyoming (1,886 mt CO2/ million dollars of GDP), West Virginia (1,767 mt CO2/ million dollars of GDP) North Dakota (1,681 mt CO2/ million dollars of GDP), Louisiana (1,145 mt CO2/ million dollars of GDP), and Montana (1,098 mt CO2/ million dollars of GDP). The 2010, U.S. average is 430 mt CO2/ million dollars of GDP. The states with the lowest carbon intensity of economic activity are also states that appear on the lower end of both energy intensity and the carbon intensity of that energy supply. These states include: New York (167 mt CO2/ million dollars of GDP), Connecticut (175 mt CO2/ million dollars of GDP), Delaware (209 mt CO2/ million dollars of GDP), Massachusetts (213 mt CO2/ million dollars of GDP), and California (214 mt CO2/ million dollars of GDP).

This analysis does not account for electricity trade, if this were factored in it can influence a state’s CO2 emissions profile. Over half of the 10 states with the highest per capita emissions the states are net exporters of electricity in at least some years. In particular, Wyoming, North Dakota, West Virginia and Montana are large electricity exporters of power produced predominantly with coal. .

Four of the 10 states with the lowest per capita CO2 emissions are consistent importers of electricity: Idaho, California, Massachusetts and Florida.

Click here to see the EIA’s monthly estimates of nationwide CO2 emissions from the consumption of energy
Click here to see short-term projection reports and here to see projection reports of energy-related carbon dioxide emissions through 2040.