Environmental Engineering Reference
In-Depth Information
Figure 4.61.
Horizontal tidal current converters. The turbine blades are a hybrid of wind
Ocean Thermal Energy Conversion (OTEC)
About 15 per cent of the solar thermal energy absorbed by the oceans is retained in surface
waters. In tropical latitudes, average sea surface temperature can even exceed 25 degrees
Celsius. Twenty-five degrees are obviously not sufficient to drive a steam turbine, but
this warm seawater from the ocean surface may be used to vaporize a fluid with a low
boiling temperature (such as ammonia, propane, or chlorofluorocarbon). This vaporized
fluid drives a turbine, is then cooled by seawater recovered from the deep sea, condenses as
liquid, and re-enters the cycle. Ocean energy can also be used to provide air-conditioning,
district heating and cooling in coastal locations in a way similar to geothermal energy
