As Congress tries to clean up the nation's energy sources and cut gases blamed for global warming, it is struggling to do so in its own backyard. The Capitol Power Plant, a 99-year-old facility that heats and cools the hallowed halls of Congress, still burns coal and accounts for one-third of the legislative branch's greenhouse gas emissions. For a decade, lawmakers have attempted to clean it up. In recent years, Congress has reduced its energy consumption. The steam and chilled-water power plant has become more efficient. It now burns more natural gas and only 35 percent coal, compared with 49...
