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Purpose:
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To store chilled water produced at night using off-peak electricity for daytime distribution to downtown St. Paul district cooling customers.
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Provider:
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District Cooling St. Paul Inc., an affiliate of District Energy St. Paul, Inc.
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Location:
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The first chilled-water storage tank is located adjacent to Hans O. Nyman Energy Center on Kellogg Boulevard; a second storage tank is located at 10th and Sibley Streets.
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Benefits:
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• Increases efficiency of chilled-water production;
• Increases reliability of the district cooling system;
• Increases cooling capacity for Saint Paul, Minn;
• Reduces regional peak electric demands;
• Reduces use of CFC refrigerants and groundwater;
• Improves regional air quality.
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Capacity:
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1994 — 2.5-million-gallons of chilled water, enough to cool approximately 2 million square feet of building space.
2003 — Additional 4-million-gallons of chilled water.
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Construction and size:
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1994 — Cylindrical steel tank, covered with insulation and an aesthetic shell, measuring 72 feet high by 80 feet in diameter.
2003 — Cylindrical steel tank, 90 feet in diameter and 90 feet high; design approved after extensive public input.
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Storage system funding:
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Funded by tax-exempt revenue bonds which are secured by long-term customer contracts and a utility rebate.
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Chilled-water storage systems elsewhere:
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Large chilled-water storage tanks are in use throughout the U.S., including a 4-million-gallon tank at 3M in Maplewood, Minn., and at Cornell University in Ithaca, N.Y.
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