With oil prices low, natural gas use growing and coal in decline, the U.S. energy sector continues to experience turmoil. The coal industry has lost 94 percent of its market value in the last five years as natural gas has virtually overtaken coal as the top fuel for electricity production. The industry also is wrestling with the consequences of climate change. Nearly 200 nations agreed at a summit in Paris in late 2015 to reduce greenhouse gas emissions to limit the rise in global temperatures. The Obama administration has unveiled its Clean Power Plan to lower power plants’ carbon emissions, but opponents have sued to block it. However, many states are addressing components of the plan — even some of the so-called coal states that are fighting the policy.