Boswell Energy Center, Minnesota Power’s largest thermal generating facility, has a total of four generating units; 3 and 4 remain online at a combined capacity of 1,000 megawatts (MW). The latter of the two has been the focus of a $350 million environmental upgrade to reduce mercury, particulates and sulfur dioxide emissions.

Minnesota Power officials said the decision to close the units, which have a capacity of 65 MW each and employ a staff of 30, is in line with its EnergyForward plan.

“The decision to retire units 1 and 2 at Boswell, though difficult for our employees and host communities, is consistent with Minnesota Power’s EnergyForward strategy of diversifying its energy mix, reducing its carbon footprint and evolving away from smaller, older coal generators,” said Allete Chairman, President and CEO Alan Hodnik.

“Multimillion dollar investments in emissions reductions and new turbine rotors at Boswell Units 3 and 4 in recent years have made them among the cleanest-operating, most highly efficient electric generators in the nation. These large, state-of-the-art units, along with the company’s investments in renewable energy and access to low cost power markets, will ensure the continued availability of reliable and affordable electricity to meet the needs of all our customers, including those who compete in global markets.”

Josh Skelton, vice president of Minnesota Power generation operations, said the company is working to avoid furloughing the affected employees.

The Duluth-based utility first submitted its Integrated Resource Plan to the Minnesota Public Utilities Commission in late 2015. In it, Minnesota Power had proposed improvements to units 1 and 2 and keeping them operational through 2024. However, the company said, an analysis of usage projections and industry trends revealed that retiring the units was the best economic decision.

Boswell Units 1 and 2 are the last of Minnesota Power’s small coal-fired units to be retired, idled or converted to cleaner-burning natural gas.