HARVEST OCEAN COLD FOR COOLING

Cold Ocean Water to be Turned Into A/C
Mark Niesse, November 9, 2009 (AP via U.S. News & World Report)

"The plan to pump frigid waters from the ocean's depths to air condition downtown Honolulu isn't a pipe dream, and it could reduce the state's dependence on fossil fuels while slashing power bills that are the highest in the nation.

"The long-studied cooling project by Honolulu Seawater Air Conditioning would extend plumbing nearly 5 miles offshore, suck 45-degree water from 1,800 feet deep, circulate frosty water into buildings' existing A/C systems and then dump it back into the sea."

Schematic of the concept. (click to enlarge)

"Hawaii's government recently approved an environmental study of the project, and the company said it plans to begin construction next year, with the 40-building system expected to come online in early 2012…If the $200 million undertaking is successful in downtown, it could later be extended a couple of miles down the road into tourist-filled Waikiki hotels. [Installation costs to customers can be offset by a $300 per ton rebate approved by the state Public Utilities Commission last year.]

"According to Honolulu Seawater Air Conditioning, buildings using the system would save up to 75 percent of the electricity they currently use on air conditioning…[even including] the electricity it will take to power the vast pumping system…[because] the buildings will no longer be using their power-hungry chillers, which are the machines that reduce water temperatures in order to cool the air in a standard A/C system."

This concept fits broadly into the category of Ocean Thermal Energy Conversion in Hawaii but at lakesides and riversides is a form of geothermal cooling. (click to enlarge)

"While the seawater A/C system is innovative, it's not revolutionary. This technology is already being used around the world in locations that have easy access to cold water, including Toronto, Stockholm, Bora Bora and Hawaii's Big Island…An early version of seawater air conditioning began nearly 30 years ago at the National Energy Laboratory of Hawaii Authority at Keahole Point, which initially used a truck radiator and box fan system…That rudimentary system lasted about six months, and the three-building system has since been upgraded to a system similar to the one planned for Honolulu…

"Honolulu Seawater Air Conditioning plans to cover downtown buildings including the 30-story First Hawaiian Center, the tallest building in Hawaii. Others include the federal courthouse, state government offices and the four-story headquarters of the state's main electric utility, Hawaiian Electric Co…The project will eliminate the equivalent of 84,000 tons of carbon dioxide from the air annually…roughly equal to 15,000 cars staying off the road…"