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by Kuulei Funn, staff writer

 

NELHA was founded in 1974 to help develop ocean energy when the Organization of Petroleum Exporting Countries restricted oil production, and caused an American energy crisis. NELHA was mandated to provide support facility for Ocean Thermal Energy Conversion (OTEC) and related research.

OTEC is a developing technology at the NELHA site. Its location was ideal for the production of ocean energy because it sits on a point from which underwater land slopes sharply down under the sea. OTEC takes advantage of the site by pumping warm surface water and cold ocean water from depths of 3,000 feet.

OTEC use these temperature differences in three different ways to produce energy. Open-cycle OTEC uses warm seawater as a working fluid by boiling it at low pressure to produce steam. The steam is then passed through a turbine that produces electricity. Cold deep sea water is used to cool the steam at the end of the cycle to condense the vapor back to liquid. If the hot water remains separated from the cold seawater, it is desalinated water and potable.

A closed-cycle OTEC uses warm seawater to heat a low-boiling-point fluid such as ammonia. When the ammonia vaporizes it drives a turbine to produce electricity. Cold sea water is used to condense the vapor back to a liquid form, and it is recycled back through the system.

A hybrid system uses both open- and closed-cycle technology to produce electricity by using the steam technology as in an open cycle, and also using ammonia as a working fluid as in a closed cycle. The system recycles the liquids as in a closed cycle, but also produces desalinated water as does the open system.

In 1979, the first closed-cycle OTEC called Mini-OTEC demonstration produced 50 kilowatts of electricity. After eight months, the operation shut down after the testing period.

“ This was the largest, most comprehensive project completed by OTEC,” said Jan War a project manager at NELHA. There are no running OTEC projects at this time, he said.

This was Hawaiian Electric Light Company’s first involvement with ocean energy. The energy produced helped to provide air-conditioning for buildings and moderate refrigeration, and is also used for mariculture operations such as the production of algae, seaweed, phytoplankton, and kelp. The facility also farmed lobsters, salmon, oysters, giant clams, and abalone.

Asian bottled water companies take advantage of the deep sea water by desalinating it and selling it for $6 per 1.5 liter bottle in Japan.

According to War, a proposal from the Ocean Engineering and Energy Systems International has been accepted for a 1 megawatt OTEC power plant to be built in 2008. The energy produced by the plant will be used to run the NELHA facility which uses between 5-6 megawatts to operate. War also said that they are also looking into ways to produce hydrogen that could be used to fuel cars. According to the Hawaiian Electric Web site, ocean-generated electricity is not yet distributed to the public.

Solar Power Energy (SOPOGY), a Honolulu company, is also proposing a project with NELHA to build a 30-megawatt facility at NELHA. According to War, the company plans to first build a testing site on one acre of land before the project is started.

For more information go to www.nrel.gov/otec/.

 

 

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