OTEC
Ocean Thermal Energy Conversion
A renewable energy technology which extracts energy from the temperature difference between cold deep ocean water and warm surface water. A vaporizer heat pump is utilized where the cold water condenses a working fluid, which is pumped into a chamber where the warm water heats and vaporizes the fluid. The expanding gas drives a turbine, and is condensed again by the cold water. The technique was first demonstrated successfully in 1979 off the coast of Hawaii. The Carnot cycle efficiency is low, but the energy is free, so low efficiency is of little concern. However because of the low efficiency very large installations will be required, with large up front capitol costs. The technology is proven, but funding to scale up the method is limiting OTEC commercialization.