A technology that produces energy by harnessing the temperature gradient between warm surface ocean water and cold water at depth. The warm surface water transfers its energy to another medium with a low boiling point, which turns into steam and powers a turbine. After exiting the turbine, the vapour is cooled and condensed by cold water pumped from the deep. For the system to work, a temperature difference of at least 20 °C is required. The energy from the OTEC system can be used, for example, to desalinate seawater.