United Nations scientists warned in an October report that global man-made carbon emissions must be eliminated by mid-century in order to avoid potentially catastrophic results.

“We’re still on the right path,” Katt Reinders said.

But she said utilities need to replace those coal plants with renewable resources and energy efficiency measures — not natural gas plants.

“The time has passed for Wisconsin to be making new investments in fossil fuel … that locks us in for decades,” she said. “It’s myopic.”

Energy analysts say there are two likely explanations for the increase in coal consumption: a turbine failure knocked Alliant Energy’s Riverside natural gas plant in Beloit offline for more than half the year, enough to knock it out of the top 10 plants; and Wisconsin gas prices were up about 14 percent on average, while coal was slightly cheaper.

Even though natural gas plants are generally more efficient than coal, when gas prices rise it can be cheaper to burn coal in some plants, said Paul Meier, an energy analyst and founder of the renewable energy consulting firm Juicebox.

Sales down, prices up