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Sustainable Energy

Wave Energy Scales Up Off Scotland

Ten wave and tidal projects will generate 1.2 gigawatts of power.

Scotland hopes to ride the next renewable energy wave. Site leases for several big wave and tidal power projects were awarded last week by the U.K. government, concluding a two-year bidding process that elicited strong interest from major utilities and energy entrepreneurs. The awards open the way for six wave energy projects and four tidal energy systems around Scotland’s Orkney Islands that could collectively generate up to 1.2 gigawatts, exceeding the U.K.’s 700-megawatt target for the bidding round. This is an immense scale for an industry that so far has installed only pilot projects involving a handful of small devices.

Leading edge: This buoyancy tube is the top edge of a 194-ton hinging device that converts wave energy into 315 kilowatts of electricity.

“This industry is about to grow up,” says Martin McAdam, CEO of Edinburgh-based Aquamarine Power, which secured a 200-megawatt site in partnership with the U.K. utility Scottish and Southern Energy, presently the country’s top renewable energy generator. Construction of the projects could begin as early as 2013.

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Scotland offers extraordinarily powerful seas, squeezed between a wide-open expanse of the Atlantic and the notoriously raucous North Sea. Waves off the Orkneys’s west coast average two meters and annually exceed 10 meters. Marine energy could provide 15 to 20 percent of the country’s total power needs, according to the London-based Carbon Trust, a government-funded entity supporting low-carbon development. The Orkney-based European Marine Energy Centre (EMEC), which includes a test-bed facility, also provides R&D support for such efforts.

If wave and tidal technologies can scale up in Scotland’s waters, marine energy experts say they will find plenty of potential elsewhere, much as the wind turbine technologies nurtured by Denmark in the 1970s and 1980s have gone worldwide. “There’s definitely a global market for both wave and tidal energy, hence the reason that you’ve got big companies looking at it,” says Amaan Lafayette, marine development manager at European power giant E.ON, which won two of the 10 Scottish leases.

The challenges are still significant. The first is proving that the technology is ready for the punishment of the open water, where many wave and tidal prototypes have met their match. For example, the fiberglass rotors on early tidal turbine prototypes installed in New York City’s East River in 2007 were fractured by unexpected turbulence. The following year, Pelamis Wave Power pulled its snake-like 750-kilowatt generators out of Portuguese waters amid technical difficulties.

EMEC director Neil Kermode acknowledges that the entire industry is still “working through a huge list of technical challenges.” But he also sees “huge progress” at Pelamis, which is assembling a second-generation machine for E.ON to be installed at EMEC this summer. E.ON’s Lafayette agrees, and says that this progress explains why Pelamis’s technology will be used at three of the 10 Scottish sites, including E.ON’s.

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.

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