Dossier Océan et énergie - Énergie Thermique des Mers

Sommaire IOA News Letters


Thomas H. Daniel
Scientific/Technical Program Manager
The Natural Emergy Laboratory of Hawaii Authority
Keahole Point, HI U.S.A.

The State of Hawaii's Natural Energy Laboratory of Hawaii Authority (NELHA) operates the Natural Energy Laboratory of Hawaii (NELH and the Hawaii Ocean Science and Technology (HOST) Park at Keahole Point on the Big Island of Hawaii. These facilities host a variety of research, development and commercial projects being performed by government, university and private groups on alternate energy and related technologies.

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Three OTEC projects are at various stages of development at NELHA:

  1. The Pacific International Center for High Technology Research (PICHTR) has recently completed construction of a 210 KW open-cycle OTEC facility, formerly known as the Net Power Producing Experiment (NPPE). In early February 1993 this plant, funded by the U.S. Department of Energy (D.O.E.) and the State of Hawaii, produced 190 KW gross electrical output during shakedown testing.We believe that this is largest production of OTEC power yet achieved. Seawater is supplied to the plant through pipelines installed in 1987 under a cooperative agreement between the State of Hawaii and D.O.E. The 1-m diameter, 1900-m long high density polyethylene ¡@ (HDPE) cold water pipeline brings up 6¢J¡@ water from 675 m depth. It provides .41 m3/s ¡@ (6,500 gpm) to the OC-OTEC plant and .43m3/s (6,800 gpm) to the HOST Park at 10.4m (34 ft) TDH. The 71-cm (28-in) diameter HDPE warm water pipeline supplies¡@ .61 m3/s (9,600 gpm) of 24.5-27.5¢J surface water to the plant at 13.0 m (43 ft) TDH.
    The power block is built around a single vertical-axis, mixed-flow turbine, rated at 210 KW gross, supported by a concrete vacuum weasel, 25 ft (7.6 m) in diameter and 31 ft (9.5 m ) high . The electrical generator is located above the turbine assembly and outside the vacuum enclosure, adding 12 ft (3.7 m) to the overall height of the apparatus. Steam is produced in an annular flesh evaporator at the periphery of the vacuum vessel.
    The steam flows up from the evaporator and enters the 3-m diameter, 7-ton, 1800 rpm turbine radially inward. The steam exits the turbine axially in  the center of the vessel. A conical exhaust diffuser provides pressure recovery enroute to a diect-contact structured-packing condenser composed of two coaxial stages. The noncondensable gases liberated from the seawater streams at pressures¡@ of 2 % to 3 % atmospheric, and a small amount of uncondensed steam are compressed and exhausted using a multiple-stage vacuum compression system. All subsystems are instrumented to measure parameters required to assess performance.
    Shakedown testing of the facility began in December 1992 and will continue through March 1993. PICHTR plans to operate the plant until February 1995 with State of Hawaii funding.
  2. A consortium consisting of ALCAN International, Ltd. of Canada, the Marconi Division of the General Electric Company of Great Britain (GEC),¡@ Hawaiian Electric Company and Makai Ocean Engineering of Waimanalo, Hawaii will install an 80 kw (gross) closed-cycle demonstration plant using existing seawater supplies at NELHA to supply roll-bonded aluminum heat exchangers developed by ALCAN and GEC. The trubine used in the 1979 mini-OTEC project is now being refurnished for this project. Ground-breaking is planned for mid-March 1993, and initial operations are expected by the end of the year. This will be the first OTEC demonstration of the new ALCAN-GEC roll bonded aluminum heat exchangers which promise significant cost reductions for future OTEC plants.

Aquaculture Enterprises, a company which has developed Marine lobster growing technology at NELH for more than five years, has now formed KAD Partners to implement a large three-part development at NELHA. The project, to be located at the south end of NELHA property, will have not only a 20-acre lobster farm producing 500,000 pounds per year-it will also include a 1 MW closed-cycle OTEC plant and a unique ocean science center. The State of Hawaii is planning to install a 56-in diameter, 9,000 -ft long, 1 km deep cold seawater pipeline which will serve this project and other deep seawater users in the area.
The OTEC plant, which will probably use ALCAN/GEC¡@ roll-bonded alumium heat exchangers, will be located at the top of the project at an elevation¡@ of about 10 m so that the water pumped for the plant will be available by gravity feed to the oceanarium and lobster farm. Though the net output at sea level would be about 500 KW, the pumping to 10 m elevation will use all of that power, so that there will be no net electrical output. The OTEC facility's location will allow the public to observe the operation of the plant as they enter the ocean science center.
The ocean science center will be the public centerpiece of this exciting project. It will utilize the large volumes of surface and deep seawater pumped for the OTEC plant to create exhibits covering the full range of habitats in the Pacific Ocean. The design creates a museum-like ambience and stresses environmental considerations by utilizing high quality educational exhibits rather than concentrating on popular tourist-type attratctions. The planners expect that up to 500,000 visitors per year will be attracted to the facility.

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Other Activities

Though NELHA's largest aquacutlture tenant, Ocean Farms of Hawaii, recently went bankrupt, there are a number of potential new users vying for access to their facilities and several other aquaculture tenants are doing very well: Royal Hawaii Seafarms continues to expand its production of high quality ogo (Gracillaria spp.); Cyanotech Corporation is making a profit from sales of Spirulina and phycobiliproteins and is planning expansions facilities for production of beta carotene rich Dunalliela; Aquaculture Technology Inc. has begun marketing shrimp and is developing stocks of oysters; Uwajima Fisheries (dba Yonezawa Suisan) is increasing production of its Hirame (Japanese flounder);
Dr. John Craven's Common Heritage Corporation has expanded its strawberry garden into a community "tropical organic garden" in which several families are planting temperate crops to grow in condensed cold water; and Onotake Inc. is building vew production facilities which will the cold seawater to provide the climate extremes required for successful mushroom culture.

The future of deep ocean water development at NELHA is bright indeed.