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Riding waves of energy

February 25, 2004, 09:00 CET

Hydro's dedication to developing renewable power caught a big wave off the coast of Scotland this week with the launch of a 120 meter-long wave power prototype - designed and built by Scots energy technology start-up Ocean Power Delivery.

“A significant part of the UK's electricity can potentially be met by wave power,” says OPD business development director Max Carcas. “There's enough wave energy off Britain’s coastline to provide three times its consumption (some 350 TWh in 2002). We estimate some five to eight percent of that can be economically realized.”

The World Energy Council predicts wave power can eventually supply 15 percent of current global energy demand.

Power potential

Technology Ventures in Hydro recognized the potential early on and now holds a minority stake in the Pelamis Wave Energy Converter project.

The UK Department of Trade and Industry is another significant supporter through its New and Renewable Energy Programme. Close to NOK 100 million (EUR 11.4 million/USD 14.3 million) has so far been invested into the Pelamis project. The prototype test - the result of six years of design and development work done by OPD in a waterfront warehouse in Edinburgh - is being carried out at the European Marine Energy Centre in the Orkney Islands.

A press event was held Monday at the Port of Leith in Edinburgh to celebrate the launch, attended by the Scottish Parliament’s Deputy First Minister, Jim Wallace.

Pelamis potential

Hydro and OPD envisages eventually placing 30-40 Pelamis units each in offshore wave power farms (covering an area approximately one square kilometer). The power plots would be capable of generating a total 30 MW of electricity - sufficient energy for some 4,000 homes. The current prototype unit generates about 0.75 MW.

“But we need to be realistic about the pace of developing wave power,” says Technology Ventures director Richard George Erskine. Using present technology, it costs about 60 øre (EUR .07/USD .09) per kilowatt to produce wave power, about twice the cost of generating wind power. Current power prices on the open Nordic electricity market are at 20 øre (EUR .02/USD .03) per kilowatt.

“We want to get prices down to 30-40 øre per kilowatt within 10 years,” Erskine says.

The EU’s ambitious goals for renewable power are driving the development of wave power. In the UK, the current 2 percent of energy produced by renewable means is expected to reach 10 percent by 2010.

Power in motion

The Pelamis Wave Energy Converter is a semi-submerged, articulated structure composed of four cylindrical steel sections linked by hinged joints. The sausage-shaped machine has a 3.5 meter diameter. Moored at its nose, the Pelamis points into the dominant wave direction. Waves travel down the length of the machine, causing hinged joints between the sections to vacillate.

"The up, down, side-to-side motion pumps high-pressure fluid to hydraulic motors through smoothing accumulators," explains Carcas. "The hydraulic motors drive electrical generators to produce power, which is fed down umbilical cables to a single subsea cable to shore, where it is tied into the land-based power grid.

“Fifteen years ago, who would have thought Europe would be producing 20,000 megawatts of the power it consumes from wind?” says Erskine. “Maybe in 10 years time, wave power will also be a major energy supply source.”

He is optmistic waves farms can be developed offshore Norway.

“Along the Norwegian coast there are many sites with ideal conditions. A combination of technological improvements to make production less expensive and international incentives, like green certificates (the guaranteed sale of power based on renewables), can make this all very interesting.”