In the past 10 years a string of ingenious technologies that harness the power of ocean waves have been developed. Many use floating devices, such as buoys, but reservoir and wave chamber systems are also being commercialised. Such innovation is driven by the prize of generating large amounts of clean power close to coastal areas, where more than 40% of the world’s population lives and works.
Now a team led by Professor Reza Alam, an expert in wave mechanics at the University of California, Berkeley, has entered the fray. They have developed an underwater ‘wave-to-energy carpet’: a thin sheet of synthetic material on the seabed, sitting on top of hydraulic actuators, which are pumped by the motion of the carpet in the waves. The resulting hydraulic pressure is then piped onshore for conversion to electricity.
Wave tank tests found the seafloor carpet was able to absorb 90% of the incoming wave energy. Unusually, the system’s efficiency increases when waves are stronger. As Carl Larsen, a professor at the Department of Marine Technology at the Norwegian University of Science and Technology, points out, many of the costs of wave power units are associated with survivability in rough weather conditions. But as these weather conditions are relatively rare, such precautions aren’t particularly cost-effective.
The water column above the modular seafloor wave carpet acts as a buffer zone, making it a more financially sound solution. Another advantage of the device, which will be located in shallow coastal waters about 60-feet deep, is that power can be harvested with minimal visual impact. The operational depth means it also poses no danger to fishing or leisure boats.
Alam’s team is using crowd-funding to develop the wave energy converter, and hopes to prove its functionality with a pilot system at the Northwest National Marine Renewable Energy Center in Newport, Oregon. The system is expected to be ready for commercial operation within 10 years. –Andreas von Schoenberg