Xcel Energy Inc. said Wednesday that April is when the Black Dog power plant in Burnsville will halt its use of coal, leaving it with two other coal-burning facilities in Minnesota.

The utility said it notified state regulators of the approximate target date for the end of the coal era at the facility, a shift that was necessary because of the "cost associated with the modifications needed to operate these coal units under new federal air emission rules," said Dave Sparby, president and CEO of Northern States Power Co.-Minnesota, an Xcel company.

"Retiring the units will benefit our customers by not only avoiding those costs, but also reducing emissions," Sparby continued.

Once April comes and goes, Xcel will have two coal-fired plants remaining: one in Oak Park Heights and the other in Becker, Minn. Xcel will continue to operate the natural gas unit at Black Dog.

According to 2013 U.S. Environmental Protection Agency data released about two weeks ago, Black Dog was the fifth-leading source of carbon dioxide emissions in the state. The greenhouse gas is considered a contributor to global warming.

Topping the list dominated by coal-burning plants was Xcel's facility in Becker, which supplies 24 percent of the power needed by Xcel's Upper Midwest customers. The utility's plant in Oak Park Heights ranked fourth.

Xcel spokeswoman Patti Nystuen said the utility has "no additional changes at this time" in the works for the use of coal by the Becker or Oak Park Heights facilities.

Paul Walsh • 612-673-4482