Missing in the Hawaii energy equation: tide power

The missing link in Hawai'i energy research may be tidal power.

In the Islands, besides the various fossil fuel plants, there is hydroelectric, geothermal, solar, wind, ocean thermal, and even wave power in either utility scale or experimental operation.

(Image: OpenHydro's system has enclosed blades and is designed to be sunk onto the sea floor without the need for drilling. Credit: www.openhydro.com)

In a candidate forum a few months ago, Kauai Island Utility Co-op board member Stu Burley argued for an ocean current power system in the channel between Kaua'i and Ni'ihau.

Nobody got up and cheered that news, but ocean currents are getting increasing interest outside Hawai'i.

Across the pond, the Northwest National Marine Renewable Energy Center (NNMREC) , is actively studying what it calls in-stream energy or hydrokinetic energy. The center is a joint project of Oregon State and the University of Washington, funded by the U.S. Department of Energy. They split the business this way: Oregon State works on wave energy, while UWash works with tidal systems.

The tidal work is focused on the tricky waters of Puget Sound, where tides whip around the various islands and rocks. The university researchers plan to install three actual systems on the ocean floor within the next two years.

The power will be purchased by the Snohomish County Public Utility District.

The technology of tidal energy is young enough that there are no standard “looks” to the systems. They're still in flux, ranging from bizarre spider-like windmill knockoffs to squat, hefty systems whose blades are enclosed to protect marine life.

The British are doing a great deal of work on tidal energy.

The theory is basically this: The tides are steady, predictable, and in certain locations can drive water at significant speeds. They generally flow in, and then out, twice a day, so a tide system needs to be able to turn itself around to face the oncoming flow—or it needs to be able to produce power with water flowing through it either forward or backward.

Using tidal energy isn't new. Tide were used to turn waterwheels hundreds of years ago. But the technology to produce utility-scale power is still quite young.

That said, it's being studied. Hawaiian Electric has looked into the possibility and has identified some of the best places around the Islands to make power out of tidal flow.

Some of the most promising locations are at the pointy places on the islands that face east and west, where the big ocean currents surge around the edges of land masses. Among the best appear to be Makapu'u and Ka'ena and La'au on Moloka'i.

Canoe paddlers and anglers know them and their currents well.

© Jan TenBruggencate 2009