Now, the energy industry is beginning to look to the sea as a source not of fossil fuels but of renewable wave power that advocates say has the potential to meet a significant share of Britain's, and the world's, energy needs.
As an island surrounded by some of the roughest seas in the world, Britain is being viewed as a world leader in the field of wave energy technologies. According to the British Wind Energy Association, wave energy could supply 3 percent of Britain's energy supply by 2020 and 15 to 20 percent in the longer term.
Michael Hay, the BWEA's marine renewables development manager, told United Press International last week that Britain had "massive potential" for wave energy due to its location. British developers of wave energy technologies were "really at the forefront of the global market for this sector," he said, and were attracting huge interest from other parts of the world. "There are a lot of people looking to the U.K. at the moment," he added.
Of the various forms of wave energy technology now in development, offshore converters offered the greatest potential, Hay said. The Pelamis model, developed by the Edinburgh-based Ocean Power Delivery Ltd., was "probably the world's most-advanced technology," and was the first full-scale offshore wave converter plugged into an energy grid anywhere in the world.
The Pelamis is a semi-submerged cylindrical structure composed of segments linked by hinged joints. The wave-induced motion of these joints is resisted by hydraulic rams, which pump high-pressure oil through hydraulic motors. The motors, in turn, drive electrical generators to produce electricity, which is then fed down a single cable to a junction on the sea bed. Several devices can be connected together and linked to shore through a single seabed cable; 120-meters long and 3.5 meters in diameter, the Pelamis has the appearance of a giant red sea-snake; but because it is situated 3 to 7 miles out to sea, even a large farm would have a low visual impact.
In March, the first of three 750kW Pelamis machines was delivered to the world's first commercial offshore wave farm in northern Portugal, with the further two to follow this month. They will provide 2.25MW as the first stage of a 24 MW plant. Enesis, the company developing the plant, has signaled its intention to purchase another 28 machines once the first stage is successfully installed.
"It's quite a milestone for us," Max Carcas, business development manager at Ocean Power Delivery, told UPI.
Ocean Power Delivery envisages future wave farms of interlinked machines occupying approximately 0.4 square miles and generating a total of 30 MW, enough to power 20,000 homes.
Carcas told UPI that offshore wave energy had the potential to be highly competitive in terms of economics. While the costs were now high -- the BWEA estimates 1 unit of electricity costs around 26 cents to produce, against a current market unit price of 5 to 7 cents -- they were lower than almost every preceding renewable technology at opening, around half the initial cost of solar photovoltaics and substantially less than wind technologies.
Wave energy could also be used in tandem with other renewable technologies to provide a stable contribution of renewable energy to the grid, he said. Whereas wind energy, for example, could be unpredictable, wave energy was a "very forecastable resource," as the effects of winds out to sea took two or three days to affect the size of waves closer to the coast. Conditions changed slowly, which enabled for effective planning and integration into the energy grid.
Producing zero carbon emissions, wave energy is one of the most environmentally benign forms of energy generation "pretty much bar anything," Carcas said. It was an indigenous and stable resource, he added: "In terms of energy security, we get a big tick in the box."
On a global scale, the power of ocean waves could be practically harnessed to provide 10 percent of current energy supply, according to the World Energy Council. It estimates that wave energy could generate 2000 TWh/yr, equivalent to current global nuclear energy production. With the entire export market for wave energy technologies estimated to be worth up to $800 billion worldwide, this is "a very big prize" for investors, Carcas told UPI.
"It's a big strategic energy resource, currently virtually untapped," he said. It could be harnessed technically, the key question now was whether governments would put in place the long-term market enablement mechanisms needed to attract capital investors, he added.
Hay said Britain's Department for Trade and Industry was pursuing a "very cautious approach," supporting small projects but capping levels of funding, which was "not necessarily helpful" for larger scale developments.
The first commercial wave farm was in Portugal largely because it had better market support mechanisms, he said.
"If the (British) government does not put in place the mechanisms to encourage long-term capital investment, all those benefits, all our strengths, may not be built upon," he said.
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