Efficiency, flexibility

The combined-cycle plant will burn natural gas to turn a pair of turbines and use the heat to create steam that will turn a third generator. A $10 million solar garden, planned for 2020, will offset about half of the electricity needed to run the plant.

Alliant says West Riverside will generate about half the carbon dioxide as a similar-sized coal plant, while emitting 99 percent less sulfur and virtually no mercury, pollutants that require expensive equipment to remove.

That will help the Madison-based utility, which serves about 960,000 electric customers in Wisconsin and Iowa, meet its goal of cutting carbon dioxide emissions by 80 percent by 2050.

But Alliant will continue burning coal at the 1,100-megawatt Columbia plant and a newer 400-megawatt generator at Edgewater that was recently fitted with new pollution controls.

“That’s going to be around for a while,” Newell said.

Thanks to advances in technology, Alliant says West Riverside will outperform even other natural gas plants, including five aging generators scheduled for retirement in 2020.

“It will be one of the most efficient plants in at least Wisconsin, if not the entire Midwest,” Newell said .