9th International OTEC Symposium

The premiere gathering on OTEC, SWAC, and LTTD will take place at Greentown Labs in Houston, TX May 4-5, 2023. More information at: www.otecsymposium.com

The Ocean Thermal Energy Association

The Ocean Thermal Energy Association (OTEA) is a volunteer non-profit organization providing a means for collection, coordination, and dissemination of information for stakeholders. Its membership and observers include individuals and organizations with interest in the development of Ocean Thermal Energy technology and closely related activities. 

Ocean Thermal refers to the naturally-occurring temperature difference in the surface and deep layers in the ocean. The surface of the ocean is warmed by radiation from the sun, while deep water remains cold and pristine. This vast ocean resource can be safely and cleanly converted to electricity via technologies such as Ocean Thermal Energy Conversion (OTEC). In addition to electricity, other useful products and services can be supported by the ocean water and temperature outflows associated with Ocean Thermal Energy. Researchers, governments, and companies around the world are working to establish and expand operational facilities for island and coastal regions. The OTEA will support their efforts.

OTEC resource is immense… Harnessing 1% of this resource, assuming a capacity factor of 100%, would mean installing 5.3GW… energy sufficient to power more than 4-million homes.

NREL – Marine Energy in the United States: An Overview of Opportunities

What is Ocean Thermal Energy?

Simply? Energy from the Ocean. Our Oceans are a vast resource (70% of earth’s surface!), that stores heat from solar radiation. The deep ocean provides an even larger resource: cold and pristine water. These resources are already providing people around the world with energy, food, and water, but we can do so much more. Ocean Thermal Energy Conversion (OTEC) is one way we can create clean, renewable energy from this naturally occurring temperature difference.

Ocean Thermal Publications

IEA-OES White Paper on OTEC

Published in 2021, it describes worldwide projects, different options to explore the thermal resource, the present status of the technology and barriers for its development, concluding with key recommendations to move beyond small demonstration plants to pre-commercial prototype units.

Using Sea Water for Heating, Cooling and Power Production (OES)

This brochure presents six interviews to give a flavor of projects in different parts of the world taking advantage of the temperature of the ocean for heating, cooling and power production.


One type of OTEC uses warm surface water, heated by the sun, in a heat exchanger to vaporize a refrigerant. The resulting vapor can drive a turbine which can then produces electricity 24/7. The vapor is then cooled back into a liquid with cold deep water so that it can be reused in a continuous cycle. The ocean water leaving the power plant changes temperature, but otherwise remains the same as it was in the ocean: a useful resource for fishery and other industries.

This is only a simple overview of one of several approaches that has already produced power. OTEC is pre-commercial, with two small-scale demonstration plants in Japan and Hawaii that are operational, and several lab-based facilities around the world. Most recently, South Korea successfully concluded an at-sea MW-scale test. As development continues and the OTEA creates more resources, we will update this site with more information.


Sea Water Air Conditioning (SWAC) is an approach to thermal energy use that focuses on the cold resource found naturally in the ocean depths, where sunlight no longer warms the oceans. Several sites around the world, use this cold resource to cool buildings with significant energy savings, as much as 90% compared to a traditional air conditioning system.

Deep Ocean Water Industries

Both surface and deep ocean water can be used in a variety of ways. Deep Ocean Water (DOW) has unique properties that have been used for development of technologies by researchers and businesses around the world. Products made with clean and renewable DOW enable sustainable and safe aquaculture, agriculture, cosmetics, bottled water, and many other products. We encourage a look into the Japan Deep Ocean Water Applications Society for more information.


The above are just a sampling of the possibilities the oceans provide us, and even better, most of the above can be combined to meet the needs of islands and coastal communities around the world. As we look to the future, the OTEA will support stakeholders in realizing the establishment and expansion of commercial ocean thermal energy.