Power plant using seawater launches

Makai Ocean Engineering Inc. officially flipped the switch of its Ocean Thermal Energy Conversion power plant on Hawaii island during a dedication ceremony Friday.

The OTEC power plant uses the temperature difference between the near-freezing deep water of the ocean and the surface waters heated by the sun to generate electricity.

“The ocean is the world’s largest energy storage system,” said Duke Hartman, vice president of business development for Makai. “We’re just extracting it, and we’re able to use it at will.”

The power plant at the Natural Energy Laboratory of Hawaii Authority is a renewable-energy facility that provides power 24 hours a day, 365 days a year. It will generate 100 kilowatts of electricity, which is enough to power 120 Hawaii homes every year. It mostly will be used for research.

Hartman said the firm power supplied by OTEC can help support the connection of more renewable energy, such as wind and solar.

“In order to get to 100 percent renewable, Hawaii absolutely needs a base load or constant steady supply of renewable energy,” Hartman said. “Solar and wind have their place, and we need them … but there really is difficulty with intermittent renewables. That is what OTEC can offer. You can ramp OTEC up when you need and down when you don’t really quickly. If you have solar farm and a large cloud goes over it and loses power, in seconds or minutes OTEC can ramp up in order to compensate for that intermittent source.”

The test facility will help Hawaii get closer to using renewable energy on a larger scale, Gov. David Ige said in a news release.

“Today marks the launch of the world’s largest operational ocean thermal power plant,” Ige said. “This plant provides a much-needed test bed to commercialize ocean thermal energy conversion technology and bolster innovation, and it serves as a steppingstone to larger plants that will provide meaningful amounts of stable, clean power to Hawaii and other locations in Asia Pacific such as Okinawa in the near future.”

The current plant is onshore, but larger plants would be located offshore. Makai’s long-range goal is to build a 100-megawatt offshore plant. Near-term steps include a 1-megawatt onshore facility and then a 10-megawatt offshore plant. In the next five years, Makai is looking to build the 1-megawatt facility.

“That is the best jumping-off point when to go offshore,” Hartman said.

Makai is in discussion with NELHA to sell excess power produced by the plant at about 19 cents per kilowatt-hour.