Xcel Energy predicts a new plan, tentatively approved by the Public Utilities Commission yesterday, to clean up the region’s air by shutting down coal plants will likely cost about $1.3 billion, raising customers’ electricity bills by around 2.4 percent (a net increase of about $1.40 a month). The plan is expected to cut power-plant nitrogen oxides, which contribute to smog, by 86 percent, according to The Denver Post. The Denver Business Journal points out that by December 2017, no power plant in the Denver area will burn pollution-causing coal, including the most controversial Cherokee 4 plant in north Denver, which will be outfitted to burn natural gas.

Environmentalists are happy with the decision, but they’re concerned that a firm date hasn’t been set for retiring the Cherokee power plant once and for all. “Until there is certainty as to when that plant will be shut down, there are risks that the largest source of pollution in the heart of Denver could be switched back to coal or that we will operate this inefficient unit too long and postpone the transition to a more modern power system,” says John Nielsen, energy program director with Western Resource Advocates (via Denver Daily News).