Proposed federal environmental regulations could shut about 13,000 megawatts of coal fired generation, boost power prices, threaten electric reliability and cost billions to retrofit or replace most of the region's existing coal fleet, according to U.S. power grid operator Midwest Independent System Operator (MISO).

Over the past few years, the U.S. Environmental Protection Agency (EPA) has proposed four regulations to clean the air and water that will affect the nation's coal-fired power plants.