ScienceNOW: What would happen if the United States stopped building coal-fired power plants? The solution may not be the panacea some have predicted. Although the plants are the single biggest polluter in the United States, contributing to smog, acid rain, and global warming, a new analysis shows that banning them would increase the cost of natural gas while doing little to aggressively combat climate change. Coal has faced strong opposition from policymakers and the public. In 2007, 59 out of …