Chilled Water Storage System


Purpose

To store chilled water produced at night using off-peak electricity for daytime distribution to downtown St. Paul district cooling customers

Benefits

Increased efficiency of chilled water production Increased reliability of the district cooling system Increased cooling capacity for St. Paul Reduced regional peak electric demands Reduced use of CPC refrigerants and ground water Improved regional air quality

Provider

District Cooling St. Paul Inc., an affiliate of District Energy St. Paul Inc.

Location

Adjacent to the Hans O. Nyman Energy Center, 76 West Kellogg Boulevard, St. Paul

Capacity

2.5 million gallons of chilled water or nearly 4,000 peak cooling tons, enough to cool approximately 2 million square feet of building space

Construction and size

Cylindrical steel tank, covered with insulation and an aesthetic shell, measuring 72 feet high by 80 feet in diameter

Timing

Construction began in May 1993; completed in spring 1994

Storage system cost and fiancing

$1.7 million total cost net of utility rebate, including design, construction, financing and start up cost; funding by tax-exempt revenue bonds which are secured by long-term customer contracts

Chilled water storage systems elsewhere

Large chilled water storage system are in use throughout the U.S., including 4 million gallon tanks at 3M in Maplewood, Minn., and at Cornell University in Ithaca, N.Y.


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