Ocean Thermal Energy Conversion (OTEC) is a renewable electricity generation technology, that utilizes the natural temperature difference in tropical oceans between the surface water and deep water. The ocean surface absorbs a large part of the sun’s energy and warms the top layer, while the deep ocean remains cold. In tropical oceans, OTEC can transform abundant thermal energy into clean electricity, generating 24/7, day and night, and year-round.
The working principle of OTEC is based on a thermodynamic cycle that converts thermal energy into electricity. Energy is subtracted from the warm water using a organic thermodynamic cycle. The principle is relatively simple. Warm surface water from the ocean is used to evaporate a working fluid with a low boiling point (e.g. ammonia). This vapor drives a turbine that is connected to an electricity generator. Cold water, pumped up from the deep ocean, is then used to condense the vapor. In this way the cycle is closed and the vapor can be reused to generate more electricity. A simple representation of the process can be seen in the figure on the right.
More information on OTEC can be found on the Bluerise website.