Wave pump: The Oyster energy converter’s pistons convert wave energy into pressurized water, which is piped to shore to a turbine power generator.
Another challenge, says Lafayette, is environmental planning. “You need to do a specific environmental assessment for each site and the specific technology to be used there,” he says. A tidal power project that E.ON backed in Pembrokeshire hit the brakes this month when the government decided to include marine energy projects in an overarching environmental assessment of offshore development for England and Wales.
Technical and environmental challenges could, of course, slow some marine energy technologies more than others. That is what McAdam is betting for Aquamarine’s Oyster wave converter, a buoyant steel flap that uses wave power to drive a hydraulic piston and send high-pressure water to a turbine generator on the shore. The design puts no fast-moving parts or power generator in the water, and McAdam claims this will minimize both technical failures and threats to marine life. In contrast, the tidal devices selected by all of the Orkney site developers, made by OpenHydro, Marine Current Turbines, and Hammerfest Strøm, use underwater turbines.
McAdam says that Aquamarine has worked through minor valve and pipeline glitches since installing the first Oyster demonstrator, a 315-kilowatt device, at EMEC in October. Aquamarine is now building its commercial-scale device–a three-flap array feeding a single 2.5-megawatt turbine–which it plans to test at EMEC next year.
Building that device is expensive, and this is the biggest challenge of all facing the industry. Developers of the Orkney sites will benefit from marine energy’s favorable treatment under the U.K.’s renewable energy mandates. However, that value only kicks in when the projects reach full scale, and developers say additional small-scale installations are needed.
“Where we’re lacking at the moment is this capital intensive phase of installing equipment to prove that it’s feasible,” says McAdam. He notes that Alex Salmond, who leads Scotland’s government, is planning a green energy conference later this year that will consider further incentives for marine energy.
A 2005 study by the Palo Alto, CA-based Electric Power Research Institute (EPRI) suggests that wave energy could be generated at comparable cost to onshore wind power off Hawaii, California, Oregon, and Massachusetts. EPRI has previously said that wave and tidal energy could meet about 10 percent of U.S. electrical demand. Paul Jacobson, ocean energy leader for EPRI, says these first-pass estimates are now being updated by a comprehensive national wave energy assessment that EPRI will complete next year, and a national tidal assessment underway at Georgia Tech.