6. Other Technologies

6.2. Ocean Thermal Energy Conversion (OTEC)

Ocean Thermal Energy Conversion (OTEC) is a method of generating electricity which relies on the temperature difference between surface and subsurface ocean waters. In order for this technology to be economically viable, the temperature difference must be 20°C and the cold deep water must be no more that 100 m below the surface1. The largest temperature differences, and therefore the largest resources for OTEC, are generally near the equator where the effects of the sun heating the ocean surface are greatest. Where this temperature difference exists it is possible to drive a heat engine. The warm water is used to heat and vaporise a liquid, normally one with a low boiling point. As the expanding vapour expands it drives a turbine. Cold water brought up from the deep water is then used to condense the vapour back into liquid2.

Environmental concerns about OTEC include the leakage of the working fluid into the environment and the effect that large-scale mixing would have on ocean currents, which are often driven by temperature gradients.

 

References

1. US, National Renewable Energy Laboratory, OTEC Site [online] http://www.nrel.gov/otec/.

2. European Ocean Energy Association (2008) Ocean Energy – Thermal Energy [online] http://www.eu-oea.com/index.asp?bid=232 (13 November 2008).

 

Further Reading

http://www.oceansatlas.org/unatlas/uses/EnergyResources/Background/OTEC/OTEC2.html.

http://www.nrel.gov/otec/what.html.

llp logoThis project has been funded with support from the European Commission (EU Lifelong Learning Programme Agreement no LLP/LdV/TOI/2009/IRL – 515). This publication reflects the views only of the author, and the Commission cannot be held responsible for any use which may be made of the information contained therein.

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