Makai Ocean Engineering

It is a renewable power technology that generates electricity using the temperature difference between warm surface seawater and cold deep seawater. Because the ocean temperature gradient is constant in tropical regions, it can generate continuous, stable energy.

In closed-cycle plants, warm seawater is used to vaporize a working fluid with a low boiling point, such as ammonia. The vapor drives a turbine to produce electricity. Cold seawater from depth is then used to condense the vapor back into liquid form to repeat the cycle.

Unlike wind and solar energy, this method provides round-the-clock power and does not require energy storage. It also supports additional applications such as seawater district cooling, desalination, and hydrogen or ammonia production.

It performs best in tropical and subtropical regions where deep cold seawater is close to shore. Ideal locations include Hawaii, Guam, Puerto Rico, the Caribbean, Southeast Asia, and other island and coastal regions.

Commercial-scale plants have not yet been built, but recent engineering advancements are reducing cost barriers. Improvements in heat exchanger efficiency, offshore pipeline design, and modular construction are making deployment at smaller scales increasingly practical. Early commercial systems are expected in high-energy-cost regions first, with wider adoption as costs decrease through continued development.

Makai has been actively developing this technology for more than 40 years through system design, thermodynamic modeling, offshore pipeline engineering, and heat exchanger innovation. The company designed and operates the largest grid-connected demonstration plant of its kind in the United States and provides engineering support for feasibility studies and early-stage commercial projects worldwide.