For decades, the United States produced more of its electricity from coal than all other fuels combined. As recentlly as 2003, 51% of US electricity came from burning coal. But the use of coal is starting to decline rapidly.

In 2011, coal will account for 41% of US power generation, down 2% from the previous year. It is expected to decline by about 4% in 2012 and about 5% in 2013, But the big drop is expected in 2014, when almost 9 gigawatts of coal-fired power plants are due for retirement. Experts think that by 2016, as much as 20% of all US coal-fire power plants may have shut down.

America’s biggest user of coal, American Electric Power Company, plans to close 25 coal-fired power plants by 2015, reducing its coal consumption from 67 million tonnes in 2011 to 50 million tonnes.

As well as the increasing cost of coal, a major reason for the closures is new Environmental Protection Authority rules. Last July, the EPA released its Cross-State Air Pollution Rule which requires reductions in nitrogen oxide, sulphur dioxide and ozone emissons in many locations. This month, it released a rule requiring plants to cut emissions of mercury, arsenic and other toxic pollutants. Rules limiting the amount of water that can be drawn from natural waterways and controlling the handling and storage of coal waste are expected to be published soon.

Some of the generating capacity will be taken up by wind and solar power, but most will come from natural gas, which produces about half the carbon dioxide, a quarter the nitrogen oxides and less than a hundredth of the sulphur dioxde produced using coal.