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Ocean Power

The seas that cover over 70 percent of our planet's surface are constantly on the move – like giant aquatic engines. They produce a prodigious amount of energy, but harnessing that power is proving a massive and lengthy challenge.

By Micheal Franco

From Discovery Channel Magazine

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In October 1973, in retaliation for US assistance to Israel during the Fourth Arab-Israeli War which broke out that month, the Arab-dominated OPEC stopped or heavily restricted oil exports to many Western nations. This move by the Organization of Petroleum Exporting Countries resulted in a massive 70 percent petrol price hike and widespread rationing in both the United States and Europe. That was when Stephen Salter, a professor of engineering design at the University of Edinburgh in Scotland, conceived a wave energy converter (WEC) to take power from the sea, with the help of funding from the British government.

"In the autumn of 1973, the Western economies were given the rare chance of a ride in a time machine and saw what the world would be like when there was no longer cheap oil," he says. "Most people thought it looked rather uncomfortable." Forward-thinking researchers, including Salter, increased their efforts to develop alternative energy sources. But according to Salter, "powerful groups set out to destroy what they saw to be a threat." Some say the groups to which Salter refers included nuclear power interests whose lobbying efforts may have caused the British government to shut down funding to his pro- gramme in 1982.

Whatever the background politics, it was only in September 2008 – 30 years after Salter’s pioneering efforts to harness the power of the sea – that the world’s first commercial wave farm was turned on off the coast of Portugal. There, in Aguçadoura, three long, red, steel snake-like devices are twisting, flexing and bobbing on the surface of the sea – producing clean, renewable energy with every move they make.

Called Pelamis, they are named after a type of sea snake and are the work of Richard Yemm, one of Salter’s students.

Once testing of the units is complete, the plan is to deploy 25 more, with a total generating capacity of 21 megawatts. Max Carcas, business development director of Pelamis Wave Power, notes with cautious optimism that, "this being the first time these machines have been deployed, we have a conservative programme of operation." He points out that the company intends to build up its experience for progressively longer periods of time, and in a wider range of sea states, until the design is fully proven.

Animal Magic
Salter’s original design was known as a "Duck," for the oval shape of its floating canister. It worked by nodding on surface waves and moving an attached piston to compress hydraulic oil which then drove an electricity-producing turbine. Ironically, the Ducks were simply too good at what they did. Each one was capable of absorbing 90 percent of a wave’s energy, making them very efficient – but unlikely to sustain such a daily pounding from the sea. This, and the lack of ongoing financial support, were key factors in the short-lived life of the early Ducks.

But the newly deployed Pelamis devices address the over-efficiency issue. They consist of a linked series of long, cylindrical chambers about the size of small commuter trains. As they float on the sea, waves cause the sections to bob up and down and bend back and forth, activating hydraulic rams in the joints. These produce power much like the Ducks were meant to, but the Pelamis units absorb less wave energy and are therefore more durable.

Antonino Lo Bianco, European head of infrastructure at project partners Babcock and Brown, says the work at Aguçadoura outlines a positive future for ocean power: "It offers huge potential, not just for Portugal but for many countries around the world where the harnessing of an inexhaustible supply of wave energy will produce clean, zero-carbon energy domestically. We expect wave power to become a widespread renewable energy technology."