OREANDA-NEWS. Alliant Energy plans to stop burning coal at two coal-fired units in Iowa, with 326MW of combined capacity.

Alliant plans to switch to burning natural gas at the 119MW unit 4 of the Prairie Creek power plant in 2017. The company by 2021 plans to end burning coal at the 207MW Burlington power plant but has not decided whether to use natural gas as an alternative. Burlington, which entered service in 1968, will remain connected to the grid until the end of its useful life, Alliant said.

The power plants in the first quarter took Powder River basin coal from Wyoming mines, Energy Information Administration data show. Burlington took supply from the Buckskin and Belle Ayr mines and Prairie Creek received deliveries from the Belle Ayr, Antelope and North Antelope Rochelle mines.

Both units are in the Midcontinent Independent System Operator (MISO) power grid. The grid operator's April survey of coal plant owners showed 15.7GW of coal capacity across the power grid critically affected by multiple federal rules in the next five years, with most retiring as a result.

Peak hour dark spreads for 10 mmBtu/MWh units at MISO's Indiana hub average $17/MWh for the calendar 2017 and drop to $16/MWh by 2019. The marginal profitability of efficient natural gas fired units is higher by 6-10pc for the same calendar terms.