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Catching a wave of energy

Researchers want to study feasibility of harnessing ocean's power

By Terry Rodgers
January 21, 2002

Waves that pummel the California coast and accentuate the state's image as a mecca of beach culture soon may be harnessed as an alternative source of electrical power.

The state Energy Commission has not funded research into wave-energy technology since 1987, but that may change very soon.

A research team led by a San Diego State University professor is seeking a $120,000 grant from the commission to study the feasibility of using ocean swells as a renewable energy source.

"As you can imagine, the motion of the ocean contains tremendous power," said Asfaw Beyene, an SDSU professor of mechanical engineering, whose funding request is expected to be voted on by the commission next month.

A Berkeley-based entrepreneur plans to test a prototype wave-to-electricity generator along the Northern California coast as soon as this summer.

"On the technology side, we're ready to go," said Mirko Previsic, founder and chief executive of Sea Power & Associates, which is trying to raise $1.2 million to install a prototype wave generator that uses a special pump to create electricity.

A 1991 study by Pacific Gas & Electric Co. estimated the swells off Northern California potentially could generate up to 10,500 megawatts of electricity, enough to supply more than 20 percent of the state's current annual power demand.

Although California is home to 40 percent of the world's geothermal plants, 20 percent of the wind-powered turbines and nearly 80 percent of solar generators, these renewable energy sources combined supply only 12 percent of the state's power.

Despite the huge potential for wave-generated energy, the PG&E study estimated that only 20 percent of the energy in waves actually could be harvested because of technological and environmental obstacles.

Beyene's research team at SDSU wants to re-evaluate that estimate and also calculate how much electricity could be produced along the state's 1,100-mile coastline. Previous studies focused on wave energy in Northern California.

"You need to know how much of the resource is out there before you go investing millions of dollars," Beyene said.

The researchers also intend to evaluate the best sites, both along the shore and outside the surf zone, to locate wave-to-electric power stations.

The study would examine practical and regulatory aspects of wave generators, such as how floating power stations might affect shipping lanes and commercial fishing activity, and whether generators along the beach could be designed to be aesthetically pleasing and blend into the shoreline.

The researchers also intend to compare the cost and efficiency of existing wave-generator technologies.

There are three basic methods for converting wave energy to electricity:

* Float or buoy systems that use the rise and fall of ocean swells to drive hydraulic pumps.

* Oscillating water column devices in which the in-and-out motion of waves at the shore enter a column and force air to turn a turbine.

* Tapered channel systems that funnel waves into a small reservoir, then use the water flow to turn a turbine similar to one at a hydroelectric dam.

Experts say the most cost-effective generators would be those offshore, where the wave energy is more powerful and the potential for environmental conflicts is less.

Offshore power generators may be expensive to build and costly to maintain. There is also the problem of connecting the stations to the state's power grid by long transmission cables on the sea floor.

"On paper, these generators will work -- but none have been in the water long enough to prove themselves, with the exception of those in the United Kingdom," said David Navarro, an analyst for the Energy Commission.

Because of the uncertainties and costs, including building durable machinery to withstand the forces of nature, venture capitalists have been slow to invest in wave-energy technology.

It did not help that in 1989 a massive storm destroyed a 500-kilowatt wave generator in Norway that had operated for four years.

The PG&E study estimated the minimum cost to build a wave-to-electricity plant at $62 million.

"The most serious challenge will be to bring down the up-front costs," said Beyene, 45, a professor at SDSU for 12 years. Other countries have forged ahead with government-funded marine power stations. Norway, Scotland, Japan, Australia and Indonesia have built and are operating wave-energy stations.

"We want wave-energy technology to be recognized as one of the practical, renewable forms of energy," Beyene said. "We'd like it to have equal footing with other forms of renewable energy conversion," such as wind and solar.

At Sea Power & Associates, which recently won the grand prize at the University of California Berkeley's Social Venture Competition, chief executive Previsic said he believes technological advances will soon make wave generators more cost-effective.

"We're at the beginning of the learning curve in terms of lowering development costs," he said.

Improving technology will allow wave generators to produce electricity at a cost comparable to wind-driven turbines, which produce energy at about 4.5 cents per kilowatt-hour, Previsic said.

For now, the best wave generator technology in place in the United Kingdom is producing energy at 7.5 cents per kilowatt-hour.

In comparison, electricity generated by burning coal costs about 2.6 cents per kilowatt-hour.

While Previsic said he believes portions of the SDSU study would duplicate previous research, writing a report that summarizes the key issues in an understandable format is still a good idea.

"It's a good step for the California Energy Commission to ramp up on this form of energy technology," he said. "As with any other renewable energy source, it will take government funding to make development of this successful."

Terry Rodgers: (619) 542-4566;

Original Link:

Source: The San Diego Union-Tribune

brought to you by Global Exchange ©2001. All rights reserved.

Updated: 2016/06/30

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