In 2003, the U.S. got more than half of its electricity from coal, but low natural gas prices, state renewable energy standards and enforcement of long-standing federal haze and mercury regulations have spurred the retirement of aging plants. Coal-fired power now supplies 39 percent of the U.S. electricity market – still more than any other source, but the downward trend continues.
Will the Environmental Protection Agency's Clean Power Plan deal coal its final, fatal blow? Not right away: States won't finish formulating their plans until 2016 or later, when it should become clear which additional coal plants will be retired. Some might not have to: Arizona, for instance, could realize most of its reductions by tapping its underutilized natural gas capacity to replace coal. But if it instead brought more renewables online and implemented ambitious efficiency measures, it might be able to keep more coal.
Still, any limit on carbon is bad news for coal. Without the regulation, a Moody's Investors Services report reasoned, coal's contribution to the U.S. electricity market might not grow, but it wouldn't shrink drastically, either. With the limits, it's likely to drop more steeply. That makes access to foreign markets – through controversial West Coast ports – even more important to Powder River Basin mines.