Cutting global-warming pollution in the U.S. may not be so costly after all. A shift to wind and solar power and an expanded electric grid would allow the U.S. to reduce greenhouse-gas emissions from electricity production by as much as 80 percent without raising power costs, according to a study published Monday in the journal Nature Climate Change. The results come as President Barack Obama pushes new rules to cut pollution from the power industry, the nation’s single biggest source of emissions, even as Republicans attack the plan as an economic disaster. While the new study didn’t look at those regulations, it found a shift to a mix of renewable- and natural-gas fired power may cut electric costs by about 10 percent in 2030, compared with a more coal-reliant grid. “What the model suggests is we can get a long way, and wind and solar and natural gas can be a bridge,” co-author Christopher Clack, a physicist at the University of Colorado at Boulder, said in an interview. “There is a path that could be possible to achieve those goals, and it doesn’t necessarily need to drive up costs.”