Bismarck-based energy company to buy North Dakota's largest coal-fired power plant Rainbow Energy Marketing publicized plans to acquire the financially troubled Coal Creek Station from Great River Energy on Wednesday, after North Dakota leaders made rescuing the plant a top priority since its planned closure was announced a year ago. Written By: Adam Willis | × Coal Creek Station, North Dakota's largest coal-fired power plant, is seen in May 2020 near the town of Underwood. Michael Vosburg / Forum Photo Editor BISMARCK — A North Dakota-based energy company reached an agreement Wednesday, June 30, to buy the state's largest coal-fired power plant in a much-anticipated move expected to rescue the facility from shutting down.