Thermal energy is renewable and is generated without an impact on the environment. In layman's terms, thermal energy can be transferred to other objects, heating them, causing the molecules to move faster. Ocean thermal energy is a popular form of solar energy. The United States took a strong interest in ocean thermal energy plants in 1974 and has since expanded their use.
Ocean thermal energy generates electricity by using the temperature difference between deep and shallow waters. Typically, this energy is used to run a heat engine. The greatest amount of energy is generated by the largest differences between temperatures. For this reason, ocean thermal energy is most easily generated near the equator and in the tropics.
Oceans cover over 70% of the Earth, which the sun has time to heat on a daily basis. If made cost-effective, ocean thermal energy could solve the world's energy needs. Currently, the efficiency of ocean thermal energy is a mere one to three percent.
Ocean thermal energy technology uses a heat engine, which is technology that is used through the majority of energy generation today. The heat engine is placed between a high temperature reservoir and a low temperature reservoir. The heat flows from one reservoir to the other, and is then converted into energy. This technology is extremely popular and is used in common engines. The reverse concept is used in refrigerators.
Ocean thermal energy has benefits other than power. Air conditioning can be produced nearby thermal energy plants. The cold seawater used for the plants can be used in water coils. This thermal energy can provide enough air conditioning for a large building, saving $200,000-$400,000 annually in energy bills.
This technology also produces chilled water for agriculture. Chilled-soil agriculture requires cold sea water to flow through underground pipes, thus chilling the surrounding soil. This temperature difference between the soil and the plant leaves allows the plants to feel as if they are grown in the subtropics.
Desalinated water can also be produced with the use of ocean thermal energy. This can be produced in open- or hybrid- cycle plants using surface condensers. This is done by condensing steam by indirect contact with cold sea water. This creates relatively low levels of impurities in seawater and allows for drinking.