Although still the largest single fuel for electricity generation, coal's share of monthly power generation in the United States dropped below 40% in November and December.
The last time coal's share of total generation was below 40% for a monthly total was March 1978. A combination of mild weather (leading to a drop in total generation) and the increasing price competitiveness of natural gas relative to coal contributed to the drop in coal's share of total generation.
Natural gas prices have dropped significantly this winter, leading the generators in some states (such as Ohio and Pennsylvania) to significantly increase the share of natural gas-fired generation. Natural gas combined-cycle units operate at higher efficiency than do older, coal-fired units, which increases gas's competitiveness relative to coal.
Total electricity generation was down 7% in December, compared with December 2010. Despite this decline, generation from natural gas rose 12% to 86 terawatthours. Coal-fired generation, however, fell by 21% between December 2010 and December 2011, to 132 terawatthours.
