ive competitors vying for the £10 million ($16.6 million) Saltire Prize, offered by the government of Scotland to the first company able to create a viable green energy system that taps the energy constantly churning offshore. (Terry Garcia, National Geographic executive vice president for mission programs, chairs the Saltire Prize committee.) Scotland has some of the world's most promising wave and tidal energy resources and has led the way in promoting their development. (Related: Ocean Energy Teams Compete for $16 Million Scotland Prize.)
Seafloor "Magic Carpet" For Power, Desalination, and Coastal Protection
Reza Alam, a UC Berkeley engineer and expert at wave mechanics, has created a power-producing "magic carpet" that serves as an artificial ocean bottom with multiple applications.
"Mud is known to very strongly dampen ocean waves. Within a distance of a couple of hundred yards even very strong waves can be completely dampened out," he said. "So we were inspired to wonder if a synthetic carpet could respond similarly to the action of waves and absorb that same amount of energy."
The device features a thin rubber or elastic composite carpet stretched across across a grid of cylinders and double-action piston pumps. The carpet adopts the up and down wave motion of its waters and subsequently moves the attached piston pumps to produce hydraulic pressure with multiple applications.
"The first idea was desalination, near the device or onshore, because high-pressure water is something we need for that," Alam explained. The system can also be customized to deliver compressed air, rather than water, for offshore aquaculture, where it could be used to move cages and oxygenate water.
And of course the system could generate electricity—perhaps in surprising quantities. In recent wave tank tests, it absorbed more than 90 percent of incoming wave energy. With that kind of results, Alam estimated, a single square meter (11 square feet) of carpet system on a seafloor could power a pair of U.S. homes. A 100-square-meter (1,076-square-foot) patch on the California coast would equal the power production of a 6,400-square-meter (68,889-square-foot) solar panel array.
The ocean wave energy converter is meant to be set in 60 feet (18 meters) of water, where it's protected from storm damage by the water column above and would be largely invisible to those on shore. It must be carefully sited to avoid sensitive areas for marine life, like reefs, as well as recreational areas like surf breaks. But because the system greatly reduces wave impacts by absorbing their energy, it could also be strategically deployed to create "safe zones" near coastlines, protecting harbors or slowing erosion. "The idea first was producing power," Alam explained, "but when we presented it in conferences, the feedback I got was that protecting harbors was probably a more immediate application of this idea. Then you don't even need a pump, just the material to absorb the energy of the waves."
The carpet is currently undergoing wave tank tests and should move to open ocean trials by 2016, Alam said.
Buoys Boost Energy, Thwart Pirates, Perform Sea Surveillance
The buoys being installed for the large wave energy project off the coast of Victoria, Australia, might also be able to make the seas safer.
Ocean Power Technologies (OPT) PowerBuoys are anchored to the ocean floor but move freely up and down with the ocean swells, driving an onboard piston-like structure to power a generator and produce electricity sent to shore via subsea cable. They boast sensors that monitor their own performance and the ocean's movement, able to switch off power production when waves are too large and strong.
The buoys may avoid one challenge that offshore wind turbines have faced: At 38 feet (11.5 meters) high, the buoys present a far lower profile than offshore wind turbines, which can tower more than 440 feet (135 meters), and according to an OPT fact sheet, they are not highly visible at a distance of 3 miles (5 kilometers) from shore. Some offshore wind projects have sparked opposit