Alliant EnergyCorp. has started construction of a new 700-MW combined-cycle,natural gas-fired power plant near Beloit, Wis.

The approximately $700 million of the willreplace several coal-fired and aging natural gas-fired plants Alliantsubsidiary Wisconsin Power andLight Co. is retiring.

Wisconsin regulators approved the project in March. Alliant expects tocomplete the project by early 2020, according to a company release.