The Environmental Protection Agency has proposed the first-ever limits on greenhouse gas emissions from new power plants. Under the rule, new power plants would be required to keep emissions under 1,000 pounds of carbon dioxide for every megawatt hour of electricity. While Republicans are vowing to fight the measure for going too far, some environmental groups have criticized the Obama administration for exempting existing plants as well as allowing a number of loopholes. The rule exempts pollution from burning biomass and also grants waivers to plants that use carbon capture and storage technology, whose efficiency is under dispute. In a statement, Greenpeace USA called the new rules “welcome, but disappointing.”