On May 5, 2010, the United States Energy Information Administration (“EIA”) released a report, “U.S. Carbon Dioxide Emissions in 2009: A Retrospective Review,” showing the largest decrease in energy-related carbon dioxide emissions since EIA started collecting emissions data in 1949. The seven percent drop (405 million metric tons) in 2009 is a stark contrast to the consistent increase in emissions throughout the 1990s.
Emissions have declined since 2000 by just less than an annual average of one percent; however, 2009 was an exceptional year in which the electric power sector alone had a 205-million metric ton decrease in carbon dioxide emissions. The EIA report attributes the drastic decrease to four major factors: population, per capita gross domestic product (“GDP”), energy intensity of the economy (energy consumed for each unit of economic activity), and carbon dioxide intensity (carbon dioxide per unit of energy consumer).
Although the U.S. population increased, the other three factors combined to make the seven percent decrease in emissions in 2009. The per capita GDP fell by 3.3 percent, and the total U.S. GDP fell by 2.4 percent due to the downturn in the economy. Both energy intensity and carbon intensity both fell by more than 2 percent each.
The energy intensity factor declined in 2009 due to decreased electricity demand of approximately 4.3 percent combined with the decrease in GDP. The carbon intensity of the energy supply fell because coal emissions decreased by 12 percent, petroleum emissions dropped by 5.3 percent, and natural gas emissions were down 1.6 percent. This was due primarily to switching fuel to natural gas as coal prices increased and the increased use of renewable generation. Nuclear generation declined in growth, but still increased its share of the fuel supply mix.
The full version of the EIA report is available at http://www.eia.doe.gov/oiaf/environment/emissions/carbon/?featureclicked=2&.