In 2010, total net generation increased 4.3 percent from 2009 levels. Cooling degree days for 2010 were at an all-time high and were 18.3 higher than they were in 2009. Net generation attributable to coal-fired plants rose 5.4 percent. Natural gas-fired generation was up 6.6 percent. Nuclear generation rose 1.0 percent, while petroleum liquid-fired generation was down 9.9 percent.
In 2010, coal-fired plants contributed 44.9 percent of the power generated in the United States. Natural gas-fired plants contributed 23.8 percent, and nuclear plants contributed 19.6 percent. Of the 0.9 percent contributed by petroleum-fired plants, petroleum liquids represented 0.6 percent, with the remainder from petroleum coke. Conventional hydroelectric sources provided 6.2 percent of the total, while other renewables (biomass, geothermal, solar, and wind) and other miscellaneous energy sources generated the remaining 4.5 percent of electric power.