Survey of Energy Resources 2007
OTEC Country Notes
United States of America
Hawaii remains the focus of US activity in OTEC/DOWA, primarily through work carried out at the Natural Energy Laboratory of Hawaii (NELHA) facility at Keahole Point.
In 1979 'Mini-OTEC', a 50 kW closed cycle demonstration plant, was set up at NELHA. It was the world's first net power producing OTEC plant, installed on a converted US Navy barge moored 2 km offshore: it produced 10-17 kW of net electric power.
In 1980 the Department of Energy constructed a test facility (OTEC-1) for closed cycle OTEC heat exchangers on a converted US Navy tanker. It was not designed to generate electricity.
In the early 1980s a 40 MW OTEC pilot plant was designed. It was to be sited on an artificial island off the Hawaiian coast. However, funding was not forthcoming and the plant was not constructed.
An experimental 210 kW (gross electrical) open cycle OTEC plant was designed and operated by the Pacific International Center for High Technology Research (PICHTR) at Keahole Point. It produced a record level of 50 kW of net power in May 1993, thus exceeding the 40 kW net produced by a Japanese OTEC plant in 1982. The plant operated from 1993 until 1998 and its primary purpose was to gather the necessary data to facilitate the development of a commercial-scale design. Following the experiments, the plant was demolished in January 1999.
A further PICHTR experiment at NELHA employed a closed cycle plant to test specially developed aluminium heat exchangers. It used the (refurbished) turbine from 'Mini-OTEC' to produce 50 kW gross power. During initial operation in May 1996, corrosion leaks developed in the heat exchanger modules; the plant had to be shut down and the units re-manufactured. From October 1998, when the new units were received until end-1999 - the end of the project - data were collected on the heat exchange and flow efficiencies of the heat exchangers and thus on the economic viability of competing types of heat exchangers.
In addition to research into ocean thermal energy, NELHA has established an ocean science and technology park at Keahole Point. Cold deep seawater is pumped to the surface and utilised for the production of energy, air-conditioning, desalination, fish farming, agriculture, etc.
NELHA has reported that during fiscal year 2006 a letter of understanding had been signed with Ocean Engineering & Energy Systems (OCEES) of Honolulu to construct an OTEC plant utilising the 55 inch pre-existing cold water pipes. At the beginning of 2007 negotiations were continuing, with an expected operational date of 2009 for the 1-1.2 MW plant.