The US state Department of Environmental Protection has approved $725m worth of pollution control equipment for a coal fired western Pennsylvania power plant.

Businessweek.com reports that the Homer City Generating Station is the state’s second-largest coal fired plant and produces enough energy to power 2 million homes.

The Sierra Club and other environmental groups have said the pollution controls aren’t good enough and have threatened to sue over clean air violations and have pushed to close the plant about 45 miles northeast of Pittsburgh.

The plant is owned by General Electric and operated by Irvine, Calif.-based Edison Mission Energy, which says the new equipment will reduce sulfur dioxides by 84 percent, mercury by 90 percent and soot by 57 percent.

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