The Public Utilities Commission ordered Xcel Energy to study the cost of new pollution control equipment at two of its coal-burning units in Sherburne County and compare that with the cost of replacing them with a cleaner alternative. Environmental groups consider the order a victory, but Xcel says it was planning something similar. The study is due next summer.

Gov. Dalrymple says if Minnesota energy regulators require utilities to pay more to burn coal it will hamper North Dakota's growing lignite industry, which already provides a large share of Minnesota's electric power. Regulators here imposed higher costs on coal-burners as part of a plan to require utilities to generate a quarter of their energy from renewable sources by 2024.

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.

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.

Officials at the Prairie Island nuclear power plant are investigating what it calls an "unusual event" after a piece of security equipment failed Wednesday afternoon, according to a news release. Xcel Energy said no radioactive material was released during the incident and there is no danger to the public or its workers.