Honolulu Seawater Air Conditioning to Begin Construction of Largest Seawater District Cooling System

Honolulu Seawater Air Conditioning (HSAC) will utilize ocean thermal energy technology to provide air conditioning to as many as 40 large commercial buildings in the downtown area of Kakaako, Honolulu.  The deep seawater infrastructure with a rated cooling capacity of 25.000 tons will cool up to 40% of the urban area on the island of Oahu. With a budget of $250 million dollars, the construction will begin shortly. Multiple companies have already signed contracts with HSAC. In a state where customers pay three times the national average electricity rate, overall savings in air conditioning costs have not been confirmed. However, electricity consumption is expected to decrease by up to 75%, and according to HSAC, the amount of potable water used for cooling will be reduced by over 260 million gallons, 84 million gallons of sewage will be reduced, and 84,000 tons of carbon dioxide emissions will be avoided.

At the district cooling plant, cold seawater (at 44°F) will exchange heat with a freshwater stream, increasing the seawater temperature by 10 degrees.  The coldwater pipe will be 5 feet in diameter, 2000 feet deep, and reach 4 miles offshore.  To withstand the Hawaiian tropical weather, 100 piles will secure the pipe to the ocean floor. Construction of the project will create 1000 jobs. Despite concerns that the project will disturb marine life, a permit has been issued by the National Marine Fisheries Service and construction is expected to begin in March, 2013, following the whale mating season. Additionally, during construction, a marine mammal scientist will be present. The project is still pending approval from the Army Corps of Engineers and State Health Department. Operation is expected to begin as early as 2014.

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