A Minnesota group wants to help Honolulu building owners cut electricity costs by 35 percent with an air-conditioning system that uses deep, cold ocean water. The company, Honolulu Seawater Air Conditioning LLC (an affiliate of Market Street Energy Co.), is scheduled to break ground next year on a $145 million cooling station near downtown Honolulu; it plans to begin operating in June 2010.
Sea-water air conditioning, a type of district cooling system, is available in Sweden, Toronto and Ithaca, N.Y. There also is a small, sea-water cooling system at the Natural Energy Laboratory on the Big Island. “Sea-water air conditioning on a large scale is fairly expensive. It is new and different for Hawaii, but the technology itself is not new,” says David Rezachek, associate development director for Honolulu Seawater.
The company hopes to secure a lease on one of three possible locations adjacent to Kakaako Waterfront Park. Rezachek says the most ideal site is in a parking lot behind the former Gold Bond building at 677 Ala Moana Blvd. Exactly how does sea-water air conditioning work? Below is a step-by-step illustration of the proposed project in downtown Honolulu:
Illustration: Kelly Hironaka
1. The sea water arrives at a cooling station, where heat exchangers transfer cold from the sea water to freshwater. The sea water and fresh water never mix.
2. The cold freshwater is delivered to buildings via an enclosed circulation system. The cool temperature from the water is used to provide air conditioning to as many as 65 buildings.
3. Afterwards, the water returns to the cooling station via an enclosed circulation system.
4. After passing through the station, the water returns to the ocean at a shallow depth, where the water’s temperature matches the ocean’s temperature.
Once built, Honolulu Seawater’s $145 million cooling station would provide sea-water air conditioning for a large swath of Kakaako and downtown Honolulu, stretching from Nuuanu Avenue to Ward Avenue and from Vineyard Boulevard to the ocean. The company also plans to develop a similar system for Waikiki and additional areas if all goes well.
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