Energy Information Administration, coal's share of monthly power generation dropped below 40 percent in the last two months of 2011 -- the lowest percentage of total generation since 1978.The 39 percent share of total electricity generation in November and December was caused by the combination of mild weather, which resulted in an overall decrease of 7 percent in power generation in December when compared to December 2011 and competition from natural gas, the EIA reported.
While coal's share of U.S. generation has declined, U.S. production of coal increased in 2011, the EIA reported in February, due to exports, primarily of coal from the Appalachian region. This region produced bitumous coal, which is used for electricity and metallurgical coal in the steel-making process.
Production from the Western region, where low-sulfur coal is produced mainly for power plant use due to its lower emissions, was down slightly in 2011 due to the switch of power plants to natural gas and flooding during the spring and summer, the EIA stated.
93 percent of the coal produced in the U.S. last year was used for electric power, reported the EIA. What was not used by utilities was exported to countries such as India, Japan and South Korea. Flooding in export-leading Australia caused greater demand for U.S. coal -- a 31 percent increase over 2011 exports.
According to the EIA, in December 2010, the natural gas-provided share of electricity generation was at 22 percent. A year later, it was 26 percent. Nuclear and hydro power also saw small share increases in a year's time. Nuclear now accounts for 22 percent of the U.S. electricity generation. Hydro accounts for 7 percent.
Coal generation in the U.S. is expected to dip even lower with coal-fired plants closing due to new EPA regulations, the Institute for Energy Research reported in February. The institute combined closure announcements with EPA modeling to figure that the EPA's prediction of closures is less than half the actuality of more than 33 GW of power generating capacity lost due to the regulations. This represents nearly 10 percent of the country's coal energy capacity.
The EPA regulations recently put in place include the Mercury and Air Toxics Rule Utility MACT and the Cross State Air Pollution Rule -- both designed to reduce airborne emissions and improve air quality.