TESTING Prototype shows Seadog concept can work.

A demonstration of a novel technology that uses the kinetic energy of ocean waves to generate electricity is scheduled for deployment off the California coast by fall. Similar in concept to pumped-storage hydropower designs, it protects sensitive electrical equipment from corrosive seawater by locating turbines, circuitry and transmission cables on land.

Under the patented "Seadog" system, a buoy riding the up-and-down motion of waves drives an attached piston (click here to view illustration). The piston draws in seawater, then expels it into a 24-in.-dia buried pipeline running to the shore. The pressure build-up continuously pushes the water up a coastal bluff into a reservoir. From there, it is discharged through an off-the-shelf hydroelectric turbine to generate electricity before the salt water is returned to the ocean.

A single demonstration pump not connected to an onshore reservoir will be deployed off Humboldt County, Calif., by November. The buoyancy block will float inside a cage of piles driven into the sea floor and extending about 35 ft above mean high water, allowing sea swells of 10 to 12 ft to drive the pump.

"Permitting will take a long time," frets Roger Bedard, proposal manager at the Electric Power Research Institute, Palo Alto, Calif. He says the technology owner and project developer, Independent Natural Resources Inc., Eden Prairie, Minn., may experience a longer delay from permitting than it is prepared to accept. But INRI Vice President Doug Sandberg says he is hoping for a permit waiver for the demonstration, which "is no more invasive than putting in a buoy." If the demonstration is successful, a 16-pump array with onshore facilities would follow. Sandberg expects permitting to take 12 to 24 months. A contractor has not yet been selected, but firms "are standing in line," he says.

The land-based portion "is, in effect, a mini-hydroelectric project," says Chris Guay, an oceanographer at the Lawrence Berkeley National Laboratory and consultant to INRI. The hybrid design allows the project to sidestep the intermittency challenges of renewable power because electricity can be generated on demand rather than subject to the whims of nature, says Guay.

The company recently tested a 1Ú32-scale prototype at the Offshore Technology Research Center at Texas A&M University, College Station. Sandberg says the performance validated laboratory predictions. With its 65-in.-dia buoyancy block and a 4-in.-dia piston-head, the prototype created "1,200 lb of lift that translated into a maximum of 187 psi. For every one psi, we could move water 2.33 ft," he says.

The company now intends to scale up the pump to full size in a marine setting. The test will identify any mitigation needed for environmental impact, such as small marine life entering the piston cylinder. INRI also hopes to show that the Seadog technology can be used to pump feedwater into desalination plants.

With a nameplate generating capacity of 750 kW, the wave farm would be located just beyond the breaker point–a distance of up to one mile from shore. The site depends on the configuration of the continental shelf and the onshore reservoir needs a minimum elevation of 150 ft. "We have estimated that we can be in anywhere from 50 to 200 ft of water," says Sandberg. He estimates a total project cost, including permitting, of roughly $3 million.