Coal Creek Station near Underwood, ND.

Trains, trucks, cars and conveyors make Rainbow Energy’s Coal Creek Station near Underwood, North Dakota, look like a giant model of perpetual motion.

Built in the late 1970s, the power plant is North Dakota’s largest. It consists of two units – both rated at 550 megawatts. Unit 1 began producing power in 1979 and Unit 2 in 1980. Together, they provide much of the electricity that is sold by Rainbow Energy to 28 electric distribution cooperatives that serve about two-thirds of the geographic area of Minnesota.

The power travels more than 400 miles by direct current (DC) transmission lines from Coal Creek Station to a large substation just west of the Twin Cities. There, the power is converted from DC to alternating current (AC) where it travels to distribution cooperatives serving about 1.7 million people.

About 8 million tons of lignite coal comes from the Falkirk Mine, owned and operated by The Falkirk Mining Company, a subsidiary of North American Coal Corporation, every year.

Fly ash collected in the electro-static precipitators at Coal Creek Station is hauled away by truck and train to ready-mix concrete companies in the Upper Midwest. The fly ash is a replacement for Portland cement and is in demand throughout the region because it makes the concrete more flowable, stronger and easier to finish.

The fly ash has another benefit. It reduces the need to make cement which saves on costs and the environment.

Trains not only haul away fly ash, they also haul away coal that has been beneficiated through a patented DryFining^TM process. By using waste heat, the coal is dried, which increases its BTU value. Some of the dried coal is hauled by covered train cars from the Coal Creek Station to the Spiritwood Station east of Jamestown.

Trains can also be found hauling corn to the ethanol plant and hauling away ethanol, which is blended with gasoline for transportation fuel. The Blue Flint Ethanol plant is located just east of the power plant and has been operating for the past 10 years.

With all this activity, Coal Creek Station is one of the most efficient plants in North Dakota and one of the cleanest.

When originally built, the desulfurization system could scrub 60 percent of the unit’s flue gas. Through upgrades, that percentage has now climbed to allow scrubbing of more than 90 percent. In addition, the plant has also reduced its nitrous oxides and mercury emissions – keeping the plant well within its permitted limits.

Coal Creek was purchased by Rainbow Energy in 2021.