OTEC: an introduction
Ocean Thermal Energy Conversion (or OTEC), is an energy technology that converts solar radiation to electric power. OTEC systems use the ocean's natural thermal gradient as a energy source. Across a wide band of tropical latitudes where strong sun raises the sea's surface temperature beyond 20 C°. above that of the low temperature of the water lying 1000m or so down, it becomes possible to produce a renewable energy source. The theory, which has been around for 120 years, is that if cold water is pumped up from the depths and connected to warm surface waters via a heat exchange system, a net energy gain can be harvested.
To date there have been a number of successful experiments that have been conducted in the warm seas off Japan and Hawaii. There are now some large concepts on the verge of operation, with land-based concepts around the 10MW and floating OTEC ships which could produce 100MW. The additional benefit of this style of energy generation is that produces the useful by product of fresh drinking water and a supply of cool, nutrient rich seawater which can be used to enhance such activities as Mariculture.
It is expected that OTEC could play an important role in providing electricity and water to tropical areas, which are close to deep water.