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Ocean Thermal Energy Conversion

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Ocean thermal energy conversion, or OTEC, is a way to generate electricity using the temperature difference of seawater at different depths.


Nearly all energy utilised by humans originates from some form of cyclic heat engine. A heat engine is placed between a high temperature reservoir and a low temperature reservoir. As heat flows from one to the other, the engine extracts some of the heat in the form of work.


The oceans, which constitute some 70% of the earth's surface area, contain enormous thermal reservoirs that vary in temperature. They are a huge storage unit of the solar input. This, if economically tapped on a large scale, could be a solution to some of the human population's energy problems. The energy extraction potential is one or two orders of magnitude higher than other ocean energy options.


OTEC utilizes the temperature difference that exists between the surface waters heated by the sun and the colder deep (up to 1000 m) waters to run a heat engine. This source and sink provides a temperature difference of 20 °C in ocean areas within 20° of the equator. These conditions exist in tropical coastal areas, roughly between the Tropic of Capricorn and the Tropic of Cancer. Such a small temperature difference makes energy extraction difficult and expensive. Hence typically OTEC systems have an overall efficiency of only 1 to 3 %.






An interesting byproduct of this process is that by running the frigid pipes through heat exchangers it can produce freshwater from condensation. Constant supply of freshwater is becoming an important issue in the 21st century.






There are a few OTEC companies





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