Ocean Thermal Energy Conversion (OTEC) uses the difference in temperature between surface seawater and deep down seawater to generate electricity. It is a clean, renewable energy source that has the potential to free many economies from their dependence on oil.
- Warm surface water is hot enough to boil a fluid with a low boiling point, such as ammonia.
- The gas from the boiling fluid creates enough pressure to drive a turbine that generates electricity.
- The gas is then cooled by passing it through cold water pumped up from the ocean depths.
- The gas condenses back into a liquid that can be used again.
- The water is returned to the deep ocean.
There are pilot plants running in Hawaii and Nauru. As the price of fossil fuel rises this technology becomes more and more attractive and economical.