By Megan Treacy / Source: TreeHugger

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Hawaii is often the first to roll out new renewable energy projects and for good reason. The island state depends on imported fuel to provide most of its power, but that is changing quickly. The state has a plan to use 100 percent renewable energy by 2045 and it has already installed wind power plants, sophisticated smart grid systems, plenty of rooftop solar and, now, the first fully closed-cycle Ocean Thermal Energy Conversion (OTEC) plant in the U.S.

OTEC is a process that produces electricity by using the temperature difference between the warm ocean surface waters of tropical areas and the much colder deep water below. The plant that Hawaii has just installed pumps water from the warm shoreline as well as from the cold deeper ocean through a heat exchanger. The resulting steam drives a turbine and produce electricity at an onshore power station, pictured below.

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The OTEC plant has a capacity of 105 kW, which is enough to power 120 Hawaiian homes per year. That may seem paltry, but even at that small capacity, it’s the largest plant of its kind in the world. It will serve as a demo site called the Ocean Energy Research Center to prove the potential of this type of technology and to inspire other places in the region like Okinawa and Guam to install something similar.

The maker of this plant, Makai, has just signed on to develop a 1 MW plant on the island of Kyushu in Japan and has been working with Lockheed Martin to plan a 100 MW installation in either Hawaii or Guam. Makai says that a plant of that size, which would operate offshore, would produce enough electricity for 100,000 Hawaiian homes and could be sold at only 20 cents per kWh.

The technology is not as risk-heavy as harnessing wave power and it’s also extremely stable. An OTEC plant can operate as a base load, always producing energy regardless of whether it’s night or day or if the wind is blowing.

“The plant is dispatchable, meaning the power can be ramped up and down quickly to accommodate fluctuating demand and intermittent power surges from solar and wind farms,” Duke Hartman, vice president of business development at Makai, said to Bloomberg.

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