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Minnesota Power said it will close two small coal-fired electricity generators on the Iron Range by the end of 2018, several years earlier than expected.

The Duluth-based utility said Wednesday it will retire Boswell 1 and Boswell 2, which are part of a large power station in Cohasset, Minn., on the western range.

Those two generators, built around 1960, each can produce 65 megawatts of power.

Boswell 3 and Boswell 4, which are on the same site, can together produce 1,000 megawatts. A megawatt is a million watts. In addition, Minnesota Power has in recent years sunk millions of dollars into Boswell 3 and 4 to reduce greenhouse gas emissions.

Minnesota Power, like Minneapolis-based Xcel and utilities across the nation, has been dialing back on coal-fired power plants as concerns over climate change grow. Last week, state regulators approved Xcel's plan to close two big coal plants in Becker — each with a 682-megawatt capacity — in 2023 and 2026.

Minnesota Power had originally planned to make improvements on the two small units at Cohasset and keep them running through 2024. But the Minnesota Public Utilities Commission in June ordered Minnesota Power to shutter them by no later than 2022.

After further analysis of "projected customer needs and industry trends," Minnesota Power "determined that retiring the two small coal units in 2018 was in the economic best interest of its customers," the company said in a statement.

If the two small Boswell plants were to keep operating with coal between 2019 and 2022, Minnesota Power would be required to add more pollution controls to both, according to a filing by the Minnesota Public Utilities Commission.

Mike Hughlett • 612-673-7003