Minnesota Power says it wants to further study the environmental benefits and economic impacts. The Department of Commerce recommends closing at least three of utility's coal-burning plants by 2016. Each unit is more than 50 years old. Environmental groups have also urged closing the coal power plants, while industrial users want state regulators to disregard the advice.

Therefore, North Dakota officials feel the state should be exempt from a Minnesota law that requires utilities to pay more to burn coal, even those from out-of-state. It's part of Minnesota's Next Generation Energy Act of 2007 that requires new coal power emissions to be offset.

Xcel Energy says its Monticello nuclear power plant automatically shut down at 11:07 a.m. Tuesday, but officials aren't sure why and a cause is being investigated, the Pioneer Press reports. All plant safety systems were functioning, officials with the Minneapolis-based utility said. The shutdown posed no danger to the public or workers, Xcel officials said. The plant is not expected to be down long.

Xcel Energy will soon need to purchase new pollution control equipment if the company wants to keep burning coal at its largest Minnesota power plant in Becker. Environmental groups want the state to order the utility to study alternatives to coal, especially solar and wind power.

The Commerce Department urged the Public Utilities Commission to order the three northern Minnesota plants closed by 2017 and replaced with energy from wind or natural gas. Instead, the commission ordered Minnesota Power, which owns the plants, to study the effects of closing them and report back next spring. The average age of the plants is more than 50 years.

Minnesota's Department of Commerce recommends closing Minnesota Power’s five oldest coal-fired power plants by 2020 to save consumers money. The Duluth News Tribune reports environmental groups have also sent letters urging the Public Utilities Commission to close the plants to reduce emissions.