The nation's largest grid operator is warning it may face a major coming shortfall in electric generating capacity as utilities retire more and more traditional fossil fuel power plants. It's a challenge facing grid operators across the country as power generators mothball coal and natural gas-fired plants for various reasons, such as reducing high maintenance and regulatory compliance costs or cutting greenhouse gas emissions. ... PJM Interconnection, which manages grid operations across 13 states and the District of Columbia, published new analysis Friday showing retirements outpacing new additions in the coming years that could leave its service area short of...