U.S. Department of Energy - Energy Efficiency and Renewable Energy

Water Power Program

Ocean Power Technologies Deploys a Wave Energy Device off the Hawaii Coast

February 17, 2010

Photo of a buoy-like device floating in the ocean, with a shoreline in the distance and mountains rising behind the shoreline.

Ocean Power Technologies launched its PowerBuoy wave energy converter off the coast of Hawaii in December 2009. Enlarge this image.
Credit: Ocean Power Technologies, Inc.

Ocean Power Technologies, Inc. (OPT) announced on February 1 that it has successfully deployed one of its PowerBuoy wave energy devices about a mile offshore from a U.S. Marine Corps Base on the island of Oahu in Hawaii. The device generates up to 40 kilowatts of power from the rise and fall of the waves, and since its deployment in December 2009, it has been generating power within specifications. The company built and will operate the device as part of a program with the U.S. Navy, which is testing OPT's wave power technology. The company has been awarded $380,000 for the PowerBuoy's commissioning and in-ocean operation. Last November, OPT announced the completion of trials of its Underwater Substation Pod (USP) in waters off Spain. The USP is designed to help collect and network power and data generated by up to ten of its PowerBuoys for transmission to a shore-based electricity grid by one subsea power cable. See the OPT press releases on the USP test and the Hawaii deployment, and the OPT Web pages for the USP and the Hawaii project.

The OPT test is part a growing drive to harness ocean energy for renewable power. In late November 2009, Aquamarine Power launched what it said was the world's largest working wave energy device, known as the "Oyster." The 315-kilowatt pilot device, installed at the European Marine Energy Centre in Orkney, Scotland, produces power with a hinged flap connected to the seabed. When a wave passes, the device pumps high pressure water to its onshore hydroelectric turbine. See the Aquamarine Power press release.

Meanwhile in Norway, Statkraft has opened the world's first osmotic power prototype, which generates power by separating fresh water and seawater with an osmotic membrane. The membrane allows water molecules to pass but not salt molecules. The difference in salinity causes fresh water to pass through the membrane into the seawater side, building up pressure there that can be used to drive a turbine to produce power. Statkraft estimates that osmotic power has a global potential to produce up to 1,700 terawatt-hours annually. Osmostic power plants can be located anywhere that fresh water meets the sea. See the Statkraft press release and technology description.

A new report from Pike Research concludes that if the hydrokinetic trials now underway globally succeed, the ocean could yield as much as 200 gigawatts (GW) of power by 2025. If these pioneering projects do not prove feasible, however, marine renewable energy might reach no more than 25 GW global capacity by 2025. The report assesses the market potential for five types of marine and hydrokinetic energy technologies: ocean wave, tidal stream, river hydrokinetic, ocean current, and ocean thermal energy. It does not include osmotic power. See the Pike Research press release.