In 2010, the United States had 580 coal-fired power plants. They provided 45 percent of the nation’s electricity. By March 2018, the number of plants had fallen below 350 and coal’s market share had dropped to 30 percent, mostly because of competition from cheap natural gas, state efforts to boost renewables and stricter pollution rules. At least 40 more coal plants have announced they will close or reduce capacity by 2025, and others may soon follow. President Trump has asked his energy secretary to take emergency measures to avert these retirements. When Mr. Trump came into office, he vowed to revive America’s coal mining industry by rolling back Obama-era environmental regulations. But coal keeps getting edged out by cheaper and cleaner alternatives. At least 15.4 gigawatts of coal capacity is set to retire this year, one of the biggest years on record, according to the Institute for Energy Economics […]