Warm U.S. winter puts coal-fired power plants in deep freeze: Kemp

LONDON (Reuters) - Ultra-low natural gas prices and a milder-than-normal winter are pushing coal-fired power generators to the margins of the U.S. electricity system, adding to their financial losses and accelerating the prospect of closure.Coal-fired power plants supplied just 18% of all electricity generated across the lower 48 states in the seven days ending on Feb. 4, down from more than 28% in the corresponding period of 2019.Coal units generated an average of 1,852 gigawatt-hours (GWh) per..