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Green Building News

Using Ocean Temperature Variations to Generate Electricity

In China, a 10-megawatt power plant will take advantage of differences in ocean water temperatures at different depths

Near the surface, ocean temperatures are warm — especially in the tropics. At greater ocean depths, the water temperature is cold. An ocean thermal energy conversion plant uses these variations in the temperature of seawater to power a turbine that produces electricity. This rendering from Lockheed Martin illustrates the technology as it would be applied in a 10-megawatt plant in the waters of south China.
Image Credit: Lockheed Martin

Lockheed Martin, the U.S. defense giant, has announced plans to build a 10-megawatt generating plant that uses variations in ocean water temperatures to generate electricity. The plant will be built off the coast of southern China.

The technology is called ocean thermal energy conversion, or OTEC. According to report by the Reuters news service, the closed system uses a liquid, such as ammonia, that boils in a heat exchanger in the presence of warm ocean water to create steam and drive a turbine. Cold, deep-sea water is pumped through another heat exchanger to condense the ammonia vapor back into a liquid.

Dan Heller, a Lockheed Martin executive, said the plant will be the largest OTEC plant ever built. It will provide electricity for a new luxury resort on Hainan Island and is one of several plants in development by other countries and private companies around the world. Southern China is an “ideal” location for such a plant, the company said in an announcement about the deal.

Lockheed said the agreement, which was announced April 16, could lead to the development of plants generating as much as 100 MW of electricity.

Reignwood Group, the Thai developer that signed the deal, said the new resort would be a net-zero energy development.

Although OTEC sounds exotic, even futuristic, the U.S. Department of Energy says it was first proposed more than 130 years ago by a French physicist named Jacques Arsene d’Arsonval. The first OTEC plant, constructed in Cuba in 1930, was able to produce 22 kW of electricity.

One Comment

  1. Curt Kinder | | #1

    I remember these from the 1970s
    I grew up in New England - I remember a story about these being considered off the New England coast. The proposed power plant looked like a flying saucer atop a soda straw. An ammonia cycle was mentioned.

    If memory serves, a major issue was generating enough power to offset the pumping power needed to bring huge amounts of water up from the depths.

    I can't imagine these working at all in winter when / where sea surface temps match deep depth temps.

    I'm sure the People for the Ethical Treatment of Plankton and other BANANAS (Build Absolutely Nothing Anywhere Near Anything) will have quite a bit to say as well. They always do.

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