The first commercial energy station powered by ocean waves started up yesterday three miles off the Portuguese coast. The machine, which resembles a giant red sea snake, generates electricity that's transmitted via an underwater cable to the nation's power grid. Two more machines are expected to be added in the coming weeks, allowing the "wave farm" to
generate a total of 2.25 megawatts, enough to supply 1,500 households with electricity [Reuters]. If successful, a second phase will see energy generation rise to 21 megawatts from a further 25 machines providing electricity for 15,000 Portuguese homes [CNN].
Environmentalists love the idea of generating power from the natural motion of waves and tides, as the ocean's energy is bountiful, reliable, and creates no greenhouse gases. But the technology has been slow to mature.
Last year, a wave-power machine sank off the Oregon coast. Blades have broken off experimental tidal turbines in New York’s turbulent East River [The New York Times].
A problem with offshore moorings also delayed the Portuguese project for about a year. But wave power proponents say that some problems are inevitable with a new technology, and that most of the kinks have now been ironed out. The machines being installed in Portuguese waters were made by a Scottish company called Pelamis Wave Power;
pelamis is an ancient word for sea snake. And it is true that the machines look like giant metal snakes floating in the water. Each one has four long sections with three "power modules" hinged between them. There are large hydraulic rams sticking into the modules. As the long sections twist and turn in the waves they pull the rams in and out of the modules like pistons. The huge force of the rams is harnessed to run generators in the power modules [BBC News].
Wave and tidal power stations face more stress than other renewable energy devices, says energy expert Ian Fells:
"It's extraordinarily difficult to design a machine that will cope with the extreme violence of waves. Some wave machines are under the surface all the time -- but they are not as well developed as yet. Pelamis lies in the surface and it remains to be seen how successful it will be.... We'll just have to see how it operates over time and how it copes with serious weather conditions" [CNN].
But other companies and countries appear eager to take up the challenge as well. Pelamis plans to install machines off the coasts of Scotland and Cornwall, in southwestern England, in the next two years, and the British company Ocean Power Technologies has just deployed its first "PowerBuoy" off the coast of Spain.