See ya, carbon. On Friday, the Obama administration is set to announce the first-ever carbon limits on new coal-fired power plants, which have been blamed for global warming and pollution. The carbon dioxide would be caught in expensive technology and buried underground, and would be an incentive to focus on cleaner energy sources. Plants already in operation won’t be affected yet, but likely would be in the future, as they produce a third of the country’s greenhouse-gas emissions. The regulations will be proposed by the Environmental Protection Agency by next summer.