Making Better Surf and Cleaner Power
The latest alternative energy source taps into the great power of the oceans. This new technology relies on harnessing the power of waves. With nearly 70% of the planet being covered in water and hundreds upon hundreds of thousands of kms of coastline, one would think that this type of technology is a natural next step in creating a world powered by sustainable energy. While the power is obviously there waiting to be harnessed, the question is whether the technology is up to par.
Not only does each power station have to harness enough energy to make it worth the while, but it must also stand up to some of the most ferocious of Mother Nature’s great forces. If the station does take a beating, what will be involved in repairing it and how much will it cost? All of these are factors that will need to be investigated over the next couple of years at the existing test station in Australia and the new station to be constructed sometime in 2007 off Rhode Island.
Making Better Surf and Cleaner Power
A new device that amplifies waves and captures their energy could soon power parts of Rhode Island
By Gregory Mone | February 2006
Popular Science
Big ocean swells could one day be as exciting to homeowners as they are to surfers, thanks to an innovative new device that harnesses the power of waves to produce cheap, clean electricity. Pioneered by scientists at Energetech, a small alternative-energy company in Randwick, Australia, a prototype of the $1.5-million device is now in testing off the Australian coast, and Energetech hopes to build another one near Rhode Island by 2007. Moored several miles offshore, Energetech’s 40-foot-tall rig relies on the up-and-down motion of waves to force air in and out of a chamber, turning a turbine that produces electricity. The company’s president, Tom Engelsman, says that a full-scale unit could power up to 5,000 homes; the output depends on the size and regularity of the swells. But recent theoretical work of two Chinese scientists on amplifying wave energy could soon make devices like Energetech’s even more effective.
Step 1: Enhance Waves
The height of a wave increases as it moves into shallower water—that’s why waves get steeper as they approach the sand. According to scientists Xinhua Hu of Iowa State University and Che Ting Chan of the Hong Kong University of Science and Technology, a football-field-size array of solid columns, situated some 300 feet from the rig, could effectively act as a false ocean bottom. The part of the wave that flows through the columns would behave as if it had reached the shallows, doubling in height.
Step 2: Corral the Swells
The cylinders amplify only the part of the wave headed straight for the converter, so there’s no danger to beachgoers. As the wave enters the Energetech converter, the parabolic wall increases its height and further focuses its energy.
Step 3: Turn the Turbine
When the trough of the wave passes beneath the chamber, air is sucked downward [see diagram,facing page]. Then, as its peak rolls through, air is forced back up, spinning the turbine faster. Bigger waves mean more airflow and, according to Engelsman, “The more air you pump through, the more energy you get.”
Step 4: Light up The Mainland
A generator converts the mechanical energy of the spinning turbine into electricity, which flows by way of an underground cable to a power station that hooks up to the main grid onshore. If the Rhode Island project is approved, it will produce two megawatts of power a year, enough to power 1,200 homes.