General Description

In 1978, the City of St. Paul was selected by the U.S. Department of Energy and the Minnesota Energy Agency for a study to determine the feasibility of a modem hot water district heating system in a major U.S. city. Additional participant include the City of St. Paul the University of Minnesota, the local gas, electricity and steam utility company and the St. Paul Building Owners and Manager Association.

The favorable results of this study led to the incorporation of a district heating development company in July 1979. The final feasible studies and successful marketing were completed in 1982, and financing was arranged- in December of the same year. The first Customers received hot water service in fall 1983.

District Energy St. Paul currently provides heating service to 135 large buildings and 300 single-families residences in downtown St. Paul, representing over 23 million square feet of building space. The St. Paul hot water system is the largest installation of its kind in North America.

1990, District Energy installed an 860-kilowatt packaged cogeneration system to simultaneously generate heat and electricity. Steam from existing boilers is used to power the turbine-driven generator. Energy from the turbine exhaust steam is used to supply hot water for district heating customers. The generator is sized to meet the majority of District Energys internal electrical requirements. Excess power is sold to the local electric utility.

Also in 1990, District Energy began analyzing the feasibility of establishing a district cooling system to meet the air-conditioning needs of several potential anchor customers. Based on positive feasibility study results, the district cooling system was financed in 1991, constructed in 1992 and began serving its first customers in spring 1993. A 2.5-million-gallon chilled water storage tank was added in 1994 to help reduce - electric demands and increase system reliability. The district cooling system recently has 34 signed customers and serves 7 million square feet of downtown building space.