The Impact of OTEC

posted in: Business, Environment | 0
Jeremy P. Feakins

Ocean Thermal Energy Conversion (OTEC) and Seawater Air Conditioning (SWAC) can sound like very confusing terms. While their processes may be complex, their efforts and potential achievements can have an enormous impact in the world of sustainable energy.

Ocean Thermal Energy Conversion

The very first example of OTEC first came in the late 19th century when Jules Verne introduced the idea in his novelTwenty Thousand Leagues Under the Sea. This supposedly inspired scientists around the world to begin working on the concept for real life implementation. However, physicist Jacques-Arsene d’Arsonval is generally seen as the originator of this technology that uses the ocean’s varying temperatures to produce power.

The first facility utilizing this technology would not come about for another century, though. The world’s first net power producing facility created is found in Hawaii at NELHA (Natural Energy Laboratory of Hawaii Authority), funded by the U.S. Department of Energy.

The Process

OTEC works by leveraging the temperature differentials in our world’s oceans between cold, deep water, and warmer surface found in tropical regions like the Caribbean. This difference can be used to generate unlimited amounts of energy without the use of damaging materials. This  form of alternative energy is turning a new page in terms of accessibility, affordability, and emissions.

Closed cycle OTEC systems consist of two large pipes and a heat exchanger. Warm surface water flows in through the first pipe and is used to heat a working fluid with a low boiling point, such as ammonia. The steam produced by the boiling ammonia turns a turbine generator, thus producing electricity. A second pipe pulls colder water from deeper parts of the ocean (1,000 meters down), which condenses that steam back into a liquid state. The pipes then take the cold water back to the deep ocean and the warm water back to the surface of the ocean, and the ammonia is recycled, creating a 24/7 process that is capable of running 365 days a year.

OTEC technology utilizes the nearly 80% of the sun’s rays that are absorbed into the surface of oceans and are replenished daily, unlike fossil fuels such as oil or coal.


This technology brings an array of economic, environmental, and social benefits to the table, increasing sustainability. In terms of the economy, OTEC reduces fuel imports and capital expenses, leading to reduced energy costs for our customers, and helps stimulate economic development.

Social benefits include (but are not limited to) affordable production of fresh water, flourishing agriculture, and sustainable aquaculture through desalination, a process that extracts mineral components from saline water. OTEC is able to contain some of the deep ocean water extracted and desalinate it. This can be done at night as well when power demand is lower. By siphoning off some of the colder ocean water in addition to some of the electricity produced, OTEC can produce fresh water at a consistent rate.

In turn, the environment benefits greatly. OTEC is a green technology that keeps our planet’s well-being in mind. It produces almost limitless renewable energy without using fossil fuels, and produces zero emissions. In fact, OTEC can save up to 7,000 tons of CO2 per year. More fresh water produced means more for human consumption, which translates to fewer people going thirsty and more people practicing better hygiene.

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