Stricter clean air regulations and competition from cheap natural gas won’t slow the world’s appetite for coal, set to grow 2.3 percent in 2015, according to the International Energy Agency. Much of the demand will come from India, which burns coal for 60 percent of its electricity. Demand is rising throughout the rest of Asia, except in China, where it may have peaked. In the U.S., the Department of Energy predicts coal use will fall 2.2 percent in 2015. New rules on mercury emissions will shutter 32 coal plants next year, though coal will remain the top power production source in the U.S., accounting for about 40 percent of electricity.