District Energy operates the largest hot water district heating system in North America. The company was founded in 1979 as a public-private partnership to provide reliable, cost-effective heating service in a northern metropolitan area. In the district energy field, the company is considered the most successful in the U.S. in terms of using renewable energy sources and energy conservation.

District Energy currently heats about 80 percent of the commercial, residential and industrial buildings in downtown Saint Paul and adjacent areas, including the State Capitol Complex and all downtown city offices. Its affiliate, District Cooling St. Paul, began providing cooling service in 1993 and today serves about 60 percent of downtown buildings.

District Energy’s primary source of hot water is produced at an adjacent biomass-fueled combined heat and power (CHP) plant. The CHP plant is the largest wood-fired facility serving a district energy system in the U.S.

Hot Water District Heating System
The hot water district heating system is twice as efficient as the previous steam heating system in downtown Saint Paul, heating twice the square footage of building space with the same amount of fuel.

District heating is also cost-effective. When adjusted for inflation, District Energy customers pay less for heating today than they did 25 years ago when service began.

Chilled Water District Cooling System
The closed-loop chilled water distribution system eliminated the use of groundwater and chlorofluorocarbon (CFC) refrigerants for air conditioning, thereby conserving an important natural resource and reducing the use of CFCs, which are destroying the Earth’s protective ozone shield and are chiefly responsible for global warming.

Chilled Water Storage
Two chilled water storage tanks store water produced at night, using off-peak electricity, for daytime distribution to district cooling customers. Chilled water storage increases system efficiency and reliability, improves regional air quality, and reduces regional peak electric demands.

Combined Heat and Power Plant
A combined heat and power (CHP) plant located adjacent to District Energy is fueled by clean urban wood residue. Wood residue is a form of biomass—a sustainable, renewable energy derived from plants and other organic matter. The CHP plant simultaneously produces heat and 25 megawatts of electricity, making it more than twice as efficient as a conventional electric power plant.

Operation of the CHP plant has reduced District Energy’s reliance on coal by about 70%, reduced particulate emissions by 50%, and reduced greenhouse gas emissions by more than 280,000 tons. Thanks to district heating and cooling, approximately 150 smokestacks, 50 cooling towers, and 300 chimneys have been eliminated from the Saint Paul skyline.

Under a management agreement with the City of Saint Paul, a District Energy affiliate, Environmental Wood Supply, operates the City’s Pigs Eye Wood Recycling Center. Each year, approximately 280,000 tons of wood residue from the recycling center are converted into biomass fuel for District Energy’s CHP facility.

Operation of the biomass-based CHP plant resulted in a 2005 Environmental Initiative Award from the Minnesota Environmental Initiative.