The Future of Energy: Innovation: 7 Cool New Ideas

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At the Kiama blowhole, south of Sydney, tourists watch from a discreet distance as geysers of spray burst from a hole in the cliff top. Growing up in the area, Tom Denniss was fascinated by these eruptions, caused when waves rushing deep into a cave force a mix of compressed air and water out through a gap in the roof. Now, a few miles south of Kiama, in the industrial city of Port Kembla, Denniss and his company, Energetech, are using the principles of the blowhole to turn wave energy into electricity.

In place of a cave, Energetech's four-story-high floating power plant has an open-based, dome-roofed chamber with a narrow opening at the top. As the waves rise and fall inside the chamber, compressed air is forced in and out of the opening, past a turbine that drives a generator. The device, which has been dubbed an "oscillating water column," has been the basis of several plans for generating useful energy. But Denniss, a former lecturer in mathematics and oceanography, curved one wall of the chamber to amplify the wave, much as a car headlight's concave reflecting surface intensifies the light from the low-wattage bulb. And he designed a turbine that rotates in the same direction no matter which way the column of air is moving.

His oscillating water column successfully generated power during trials outside Port Kembla harbor in June. (A rival system called Pelamis, using 120-m-long hinged cylinders, was successfully tested in Scotland in April.) Once commissioned, Energetech's plant is expected to feed into the local grid enough clean power for 500 homes. Energetech is developing several commercial-scale projects from Israel to Rhode Island. Wave energy, Denniss says, is "more consistent, predictable and concentrated than wind. It's also inexhaustible." Having studied the ocean's power all his life, he's in no doubt that it will soon be turning on our lights.