Wave hello to ocean power

By Jan TenBruggencate
Advertiser Staff Writer

In Hawai'i we have volcano power, wind power, solar power, falling-water power, water-temperature-difference power, oil power, coal power, garbage power, sugarcane-waste power and more — but not ocean-wave power.

I wrote recently about a wave-powered electric generator built by the Scottish firm Wavegen, which captures wave energy in a tunnel like the blowholes around the Islands. Since then, several e-mails have come from engineers and companies with designs for such systems.

There is the "sea snake" device promoted by Ocean Power Delivery, viewable at www.oceanpd.com. It's a long, hinged, floating device that will be installed for the first time next year off Scotland.

It works, the company's Web site says, when the "wave-induced motion of these joints is resisted by hydraulic rams which pump high-pressure oil through hydraulic motors via smoothing accumulators. The hydraulic motors drive electrical generators to produce electricity."

The company is looking for places to install demonstration systems and "Hawai'i would be ideal," a company official said.

Another firm, Sea Power and Associates, of Berkeley, Calif., has a different design.

"Their patented system consists of a series of buoys driven by the up-and-down motion of waves. This motion is channeled through a hydraulic pump, converting ocean-wave energy into electricity," said Misha Cornes, vice president for marketing.

One benefit, the firm says, is that electricity generated from ocean-wave energy "will reduce the greenhouse gas emissions that contribute to global warming."

A Dutch firm, Teamwork Techniek, is promoting its Archemedes Wave Swing, which uses air chambers and a flywheel to convert waves to power. The system is different from others in that all parts are underwater: It uses the force of waves in the water column, not the surface wave. Because wind creates most waves, wave energy is an offshoot of wind energy, the company says.

"Wave energy is reliably present even during calm periods, unlike wind energy proper, so wave energy can also be considered as stored wind energy," the firm says.

The California Energy Commission has looked at a lot of these systems. See the Web site.

"There are currently more than 12 generic types of wave-energy systems," it says.

But as with any electric-generating system, there are issues that need to be considered. They may damage marine life and may be considered unsightly. And they may interfere with shipping, fishing and ocean recreation.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Call him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.