Otter Tail Power Co. announced that it plans to build a natural gas-fired generator in eastern South Dakota, which will help make up for the planned closure of a coal-fired power plant in its hometown. The company will invest about $165 million for the 250-megawatt plant, which will be located near Astoria, S.D., about 150 miles south of Fergus Falls. A megawatt is 1 million watts, and by that metric, Otter Tail is building a medium-sized plant. The new gas-fired plant at Astoria, which will feature a simple-cycle gas combustion turbine, will be a peaking plant, supplementing power produced at Otter Tail's planned wind farm in Merricourt, N.D. Natural gas-fired plants emit half as much greenhouse gases as coal-fired plants. The plant must get regulatory approval. Otter Tail expects the generator will go online in 2021, and employ three to five people. The Hoot Lake plant employs about 40 people.