The seemingly endless variety of wave power wannabes includes designs that work by using the motion of the ocean to send pressurized water ashore, where generators can turn that force into electricity. Such “pump-to-shore” devices are making some progress in Australia and in Scotland – could New Jersey be next?
The Asbury Park Press reported over the weekend that the company Clean Wave Energy was in preliminary talks – very preliminary, we should stress – with the borough of Point Pleasant Beach about locating a system there.
The pitch from Clean Wave Energy is that the Jersey Shore town could use the funds received from state renewable energy credits – which would be worth $120,000 annually, the company says – to pay to fix up a boardwalk that’s apparently in need of several million dollars’ worth of TLC.
The company told the paper it liked the Point Pleasant Beach location because the seafloor dropped off relatively quickly to the 50-foot depth necessary for the wave energy converters to function, allowing for the possibility of siting the devices 3,000 feet from shore instead of a few miles out.
Clean Wave Energy hasn’t tested its concept at any scale, it seems, but the company does provide a fair bit of detail on its website. The device consist of a displacement pump connected to an anchor block on the seafloor, and then linked by a flexible steel cable to a foam float encased in fiberglass. The float-pump apparatuses would shoot the water ashore through a subsea pipeline.
“As the piston is drawn down by the tension spring, it continues to draw water through the filter into the pump housing,” the company says. “When the float begins to exert an upward force on the piston, the water in the top side of the pump is forced out through the top check valve at a pressure greater than 200 pounds per square inch. This pressurized water is then conveyed through pipes to a manifold where it is joined with other pump lines to go on shore to the hydroelectric generators.”
On Page 2: Other similar devices are further along
A difference between the Clean Wave Energy concept and other pump-to-shore designs further along in development is that it has a major component actually on the surface of the water.
The Carnegie Wave Energy power converter, called Ceto, which is backed by federal and state governments in Australia and aims to have a system commissioned near Perth by the end of 2013, uses submerged buoys to deliver pressurized water onshore (while also desalinating the seawater).
The other device of note in this category is Aquamarine’s Oyster. An 800-kilowatt version is undergoing testing at the European Marine Energy Centre in Orkney, Scotland, with two more of the devices expected to join it. The Oyster is attached to the seabed at depths between about 30 and 50 feet about a quarter-mile offshore. Its hinged flap, which is almost entirely underwater, pitches back and forth in the waves, driving hydraulic pistons that push high-pressure water onshore via a subsea pipeline to drive a conventional hydro-electric turbine.