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Researchers wring energy out of ocean waves
San Francisco Chronicle


December 16, 2008

Bobbing in Monterey Bay a mile off the coast of Santa Cruz, Calif., the bright yellow buoy doesn't look like anything special. A playful young California sea lion frolicking nearby doesn't give it a second glance.

But as it is buffeted by waves, the lifeboat-size buoy does something remarkable: It harnesses the waves' power to generate electricity. Atop the buoy, two columns, each about 8 feet tall and 2 feet in diameter, hold a rubbery material that stretches and contracts like a bellows in response to the waves' motions, generating energy with every stroke.

That material, called Electroactive Polymer Artificial Muscle (EPAM) was developed by SRI International, an independent nonprofit research and development organization whose storied history includes a demonstration of the first personal computer 40 years ago.

Generating power from waves isn't new -- in fact, an entry in Wikipedia says the idea has been around since at least 1890 -- but many other approaches require costly and complicated hydraulic transmissions, SRI said. Its model, by contrast, is based on a simple, low-cost material whose motions are familiar to anyone who has ever seen an accordionist play.

"We can make electricity with something as simple as a rubber band," said Roy Kornbluh, SRI principal research engineer and the technical lead on the project.

SRI chartered a 60-foot whale-watching boat to transport researchers, journalists, investors, and observers from the Department of Energy and Pacific Gas and Electric Co. to see the demonstration model recently, on a day with clear skies and very gentle swells.

"The water is calm today so (the) fact that we are generating power from small and irregular waves is very exciting," Kornbluh said.

It is the very ordinary-ness of the rubbery material that makes it so extraordinary, SRI said.

"Typically, the simpler you can make something, the cheaper and more reliable," said Roger Bedard, ocean energy leader at the Electric Policy Research Institute in Palo Alto. Although he wasn't at the demonstration, Bedard is familiar with the SRI technology, as well as other entrants in the wave-power field.

While ocean waves seem like the ultimate renewable and nonpolluting power source, "ocean energy is probably the last of the really large natural resources we've not yet added to our portfolio of energy supply options," Bedard said.

The reason? "You're operating in a remote, hostile environment. Wind machines on land and solar arrays on rooftops are a lot easier."

Although wave power theoretically should be cheap, "installation and maintenance costs can be astronomically high," Bedard said. "The real test of any ocean energy machine is, can you make it really, really reliable? That's one of the lures of the SRI technology."

About 100 small enterprises around the world are working on ocean power, including wave, tidal and thermal projects. A report from Greentech Media and the Prometheus Institute said fewer than 10 megawatts of ocean power are currently installed but predicts the technology will reach 1 gigawatt of capacity by 2015, an annual market size of $500 million. A megawatt is enough to power 750 homes.

But efforts so far are small and diffused, and have run into technical difficulties. Last autumn, a $2 million prototype wave-power machine built by a Canadian company sank off the coast of Oregon.

The world's biggest wave-generating "farm," which began operations in September, is 3 miles offshore from Portugal. It has three 750-watt energy converters that use hydraulic rams to pump oil through hydraulic motors that drive electrical generators.

In the United States, Ocean Power Technologies, which went public last year on the Nasdaq, has deployed its PowerBuoys in Kaneohe Bay, off Oahu's windward coast, as well as offshore from its home state of New Jersey.

Bedard has high hopes for sea power.

"We think wave energy could be as much as 6.5 percent of the nation's total energy consumption," he said. "That's many, many years away; certainly not in my lifetime and I'm 65 now, so not within the next 20 years."

SRI's demo model produces a modest 20 watts, just enough to power a navigational buoy, for instance. In fact, powering such buoys, eliminating the time and expense of having to change batteries, likely will be one of the first commercial applications of this technology, said Shuji Yonemura, CEO of Hyper Drive Corp., a Tokyo company that has exclusively licensed the right to commercialize the technology.

Yonemura said he hopes that within 10 years, wave-generated electricity will be used on a large scale to feed the power grid on land. In the future, he expects the wave-generated power will cost about 7 to 8 cents per kilowatt. In Japan, wind power now costs 25 cents per kilowatt, while power from fossil fuels -- which of course has environmental implications -- costs between 5 and 6 cents per kilowatt, he said.

But meanwhile, the SRI technology is still nascent. Researchers haven't yet settled on such essentials as how to transmit the power to shore. Kornbluh said options might include an underwater cable or using the energy to convert water into hydrogen and oxygen, then piping the hydrogen to shore as a fuel source. The demo model stores the energy it generates aboard in batteries.

James Sweeney, director of the Precourt Institute for Energy Efficiency at Stanford, said wave-generated power so far has been expensive and diminutive.

"There is a lot of energy in waves, it's true," he said. "But it's very distributed so that picking up energy is apt to take a significant array of whatever you use. That in itself could have its own environmental and unsightliness problems. The real challenge is not only having it work on a small scale, but figuring out how you can have an array adequate to put all that electricity together to get a significant amount of power."


E-mail Carolyn Said at csaid(at)
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