Energy: To catch a wave (wave energy)

Energy: To catch a wave

Ocean wave energy is trying to break into the renewable-energy market, but many challenges remain. Ewen Callaway reports.

Ewen Callaway

The North Sea is not known for calm days, and neither is its inlet called Nissum Bredning, 300 kilometres northwest of Copenhagen. On a typical afternoon, windsurfers skate across the grey-green water while birds seem to hover, frozen, in mid-air. Along the horizon stretch rows of giant white windmills, their long blades whirring in the gusts.

“There's really some good action today,” Per Steenstrup shouts over the gust as a mix of sea water and rain pelts his face. Steenstrup, an engineer from Copenhagen, is 200 metres offshore, aboard a steel platform with 20 large floats on each side lined up like oars on a Viking ship. A knee-high wave washes under the platform, and the floats move up and down a dozen centimetres in quick succession.

Steenstrup opens the door to a small prefabricated structure on the platform, and suddenly a mechanical roar rises above the noise of the wind and sea. “It's a 40-piston engine running on waves,” he yells. In the control room next door to the turbine, Steenstrup peers at a computer that keeps an instantaneous pulse on the Wavestar, as the platform is called. “At the moment, the output of power is around 800 watts,” he says — enough to run a large-screen plasma television.

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