Benjamin Martin came to the tiny Japanese island of Kumejima to work as an English teacher after graduating from a business school in landlocked Arizo

The Century-Old Renewable You’ve Never Heard Of

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2022-01-25 06:00:04

Benjamin Martin came to the tiny Japanese island of Kumejima to work as an English teacher after graduating from a business school in landlocked Arizona. Now he runs a power plant fueled by ocean water. “I don’t have an engineering degree, and I do all the maintenance for our electricity,” he said. “It’s relatively easy.”

The plant, which looks like a cross between a lighthouse and a jungle gym, generates a negligible amount of power, only about 100 kilowatts. It was built in 2013 to demonstrate a process called ocean thermal energy conversion, or OTEC. The idea behind OTEC isn’t new, and it’s deceptively simple. Like most power plants, the facility uses vaporized liquid to spin a turbine and generate electricity. The difference is that instead of burning fuel, the plant gets its energy from Sun-warmed water from the ocean’s surface. Cold water pumped up from a depth of several hundred meters cools the vapor again, creating a heat engine.

For now, Kumejima depends mostly on diesel fuel, shipped in at a premium, to provide electricity for its 8,000 residents. But residents of the island hope someday to sever that dependency by building a 5-megawatt OTEC plant that with a bit of solar, could cover all of its energy demand.