Alliant Energy Corp. subsidiary Interstate Power & Light Co. will close its gas-fired M.L. Kapp in Iowa on June 1, six years earlier than planned.

The 51-year old plant had been scheduled to close in 2024, but two recent reviews showed that it is in the best interest of customers to retire the facility early, Alliant said March 21. According to S&P Global Market Intelligence data, the plant has an operating capacity of 115.4 MW.

Spokesman Mike Wagner said the plant mostly ran during times of peak demand and operated just 11 days in 2017. Wagner said the Midcontinent ISO concluded that closing the plant will not pose a reliability problem.

Alliant converted the plant from coal to natural gas in 2015. The conversion reduced emissions and operating costs while keeping the plant available to help meet energy demand, Alliant said.

The company said those needs have reduced as upgrades continue at larger power plants and more wind energy is added to Alliant's energy mix.

Alliant said it will help employees transition to retirement or other positions within or outside the company. More than half of the plant's 21 employees are eligible for retirement, Alliant said. The company is looking for potential buyers for the plant site in Clinton County, Iowa.

The company is making changes at other facilities in Iowa. This includes a plan to stop burning coal at the 181.9-MW Prairie Creek plant by 2025 and the 215.9-MW Burlington ST plant by 2021. A decision about whether Alliant will convert those plants to natural gas has not yet been made, but if the plants are converted, they will remain open as long as it is in customers' bests interests, Wagner said.