U.S. carbon dioxide (CO2) emissions resulting from energy use during the first quarter of 2012 were the lowest in two decades for any January-March period. Normally, CO2 emissions during the year are highest in the first quarter because of strong demand for heat produced by fossil fuels. However, CO2 emissions during January-March 2012 were low due to a combination of three factors.
•A mild winter that reduced household heating demand and therefore energy use
•A decline in coal-fired electricity generation, due largely to historically low natural gas prices
•Reduced gasoline demand
CO2 emissions from coal were down 18% to 387 million metric tons in the January-March 2012 period. That was the lowest-first quarter CO2 emissions from coal since 1983 and the lowest for any quarter since April-June 1986. The decline in coal-related emissions is due mainly to utilities using less coal for electricity generation as they burned more low-priced natural gas.
About 90% of the energy-related CO2 emissions from coal came from the electric power sector. Coal has the highest carbon intensity among major fossil fuels, resulting in coal-fired plants having the highest output rate of CO2 per kilowatt-hour.