MDU wants to add a second natural gas unit to the Heskett plant, north of Mandan.
It would be an 88 megawatt unit, and will serve as a “peaking” unit. That's the same as the other unit.
"You can ramp it up pretty quickly, when you need the power during a peak time," said MDU spokesperson Marh Hanson.
Hanson said this is part of the utility’s Integrated Resource Plan. That plan includes the closing of three coal-fired units – two at the Heskett plant, and the Lewis and Clark plant in Sidney, Montana. Hanson said those coal units will likely be retired by the end of March, 2022.
Hanson said this was the best cost option for MDU customers.
"It will cost our customers about half as much as if we continued to run those three coal units we are retiring," Hanson said.
Hanson said this doesn’t mean MDU will be getting out of the power-generation-by-coal business. MDU has a part ownership in the Coyote Station near Beulah, the Big Stone plant in South Dakota and a power plant in Gillette, Wyoming.
Hanson said the two Heskett units and the Lewis and Clark plant are more than 60 years old.
"They've served our customers well for many, many years, much longer than anticipated when they were first constructed in the 1950s," Hanson said. "It's time for them to retire."
The new unit at Heskett should be on line by early 2023. It is subject to review by the North Dakota Public Service Commission.