Far out at sea, the wind blows over the water's glassy surface, creating tiny ripples and eddies. Those ripples provide a rough surface for the wind to grab and push—and waves are born. The longer a gust of wind catches the water's surface, the bigger the waves become.
According to some estimates, ocean waves around the world could hold up to 10 trillion watts of energy. If humans could harness that energy, we would be able to generate renewable, predictable and pollution-free electricity. But so far, few large-scale wave-energy projects have made it off the diving board—which means that ocean-wave technology is a free-for-all in terms of design. "There are many, many different types of devices," says Paul Jacobson, an ocean-energy leader at the Electric Power Research Institute. "The technology hasn't developed to the point where a lot of the designs have been shaken out yet. And so it remains to be seen which devices will turn out to be the most cost-effective and efficient."
These five ocean-power designs could help us to ride the wave into the future of energy.
Company: Aquamarine Power
Much like its namesake mollusk, the Oyster sits on the seabed, opening and closing its jaws. The device is a large hinged flap attached to the ocean floor at a depth of about 35 feet. As the flap opens and closes, it drives hydraulic pistons that squirt high-pressure water onshore, where it drives a conventional hydroelectric turbine. "In essence, the Oyster is simply a large pump which provides the power source for a conventional onshore hydroelectric power plant," says Carrie Clement, a spokeswoman for Aquamarine.
A 0.32-megawatt Oyster has already been installed in Scotland, where it began feeding power to National Grid in 2009. Now Aquamarine Power is working on creating a 2.4-megawatt Oyster bed in the Orkney Islands in Scotland. The submerged design protects Oyster's equipment from storm damage and allows it to keep working in all kinds of weather.