HOUSTON Jan 4 (Reuters) - More than 9,000 megawatts of coal-fired generation retired in the United States in 2012 as stricter federal pollution standards move closer to reality and cheaper natural gas makes coal plants less attractive economically.
U.S. companies have retired or announced plans to shut or convert more than 36,000 MW of older coal-fired plants over the next few years as they work to reduce emissions in advance of new environmental rules and shift to less-expensive natural gas.
Eventually, the transition from coal may shut as much as 60,000 MW to 100,000 MW of coal-fired generation across the country, according to various industry estimates.
Coal plants account for about 316 gigawatts (GW) of generation in the United States, or about 30 percent of the nation's 1,039-GW electric fleet.
But many coal plants have been in service for decades and face stiff competition from newer gas-fired plants as the price of gas falls.
The average price of spot gas last year fell to a 13-year low, according to Reuters data.
Lower gas prices have depressed power prices to at least 10-year lows in several regions, making it uneconomic for generators to install costly environmental controls on older and smaller coal plants.
Those controls are necessary to keep the units compliant with the latest limits on air, water and waste emissions from the Environmental Protection Agency and some states.
Coal-fired generators were expected to produce about 38 percent of the nation's power supply in 2012, down from 42 percent in 2011, according to federal data. But the Energy Information Administration (EIA) expects coal to produce 40 percent of the nation's power in 2013.
Coal produced more than half of the nation's power as recently as 2003.
Even as coal plants shut, a few new coal plants are coming online after several years of construction.
Duke Energy put an 825-MW coal-fired plant in service last month at its Cliffside power plant in North Carolina while a unit of American Electric Power Co began operating the 600-MW Turk plant in Arkansas. .
LS Power Group expects to bring a 900-MW coal plant in Texas online this year, one year later than scheduled due to start-up problems.
U.S. power companies began planning dozens of new coal plants in the mid-2000s when natural gas prices soared and power demand was rising. Many of the projects were canceled or delayed as gas prices fell with increased production from shale formations, the recession pared power consumption and the EPA moved to tighten existing pollution limits and to begin to regulate carbon dioxide emissions.
Last month, NRG Energy canceled a plan announced in 2006 to build an 800-MW coal unit at its Limestone plant in Texas, citing the affordability of gas.
Duke and AEP are among the biggest owners of coal-fired power plants in the country. Others are Southern Co, the Tennessee Valley Authority, First Energy, NRG Energy and Xcel.