The plant, which has operated for 81 years, draws frigid lake water to be heated by a coal-fired furnace and then pipes steam to downtown businesses. The plant is inspired by a similar system in St. Paul and another one like it in Sweden.
Duluth’s heating system was privately built but sold to the city in 1979. It currently serves about 40 percent of the central business district and waterfront park area. Expansion would be difficult because it would be difficu.t top push steam any farther from the boiler.
Conversion to a hot water system would allow service to customers more distant from the boiler. Also, circulated hot water would allow for heart recovery after it has passed through the systems’ buildings. Currently, leftover steam condenses back to water and is recirculated through the city’s sewer system.
Ever-Green Energy has been hired to manage the system. The company operates North America’s largest district hot water system in St. Paul. The company is eyeing sawdust as a fuel source to supplement coal. Eight to 16 truckloads a day from area sawmills could supply up 25 percent of the plant’s fuel by 2015. Woodchips could be added with some additional equipment.
Photo credit: chefranden’s Flickr photostream