Wave Power Harvesting Via Shipboard Design

Wave power has been making inroads as a possible source of renewable energy, but has at least a couple of hurdles to overcome, according to researcher Andre Sharon: The cables needed to link the wave devices to the grid are costly – around $500,000 per kilometer – and building the devices to withstand the inevitable ravages of stormy seas can be expensive. These two issues vanish, however, under a scheme hatched by Sharon at the Fraunhofer Center for Manufacturing Innovation.

Ships, instead of permanently set buoys, are the key to the Mobile Wave Energy Harvesting plan. As detailed recently in New Scientist magazine, 50-meter-long ships would sail out to prime wave-energy spots, drop anchor, then put buoys – attached to the ships by pivoting arms – into the sea. Those same pivoting arms would be driven back and forth by the bobbing buoys, turning a generator and cranking out as much as one megawatt (MW) of electricity per ship.

Mobile Wave Energy Harvesting

image via Fraunhofer CMI

But where does the energy go? Well, the plan also turns the ships into giant energy storage devices, using unspecified batteries that could hold 20 megawatt-hours of power. Harvesting at full 1-MW power, that means it would take 20 hours to fully charge the battery.

Sharon presented his idea at the Clean Technology Conference in Boston last month. By his calculations, the Mobile Wave Energy Harvesting system would produce energy at a cost of $0.15 per kilowatt-hour (kWh). For comparison, New Scientist noted that energy from current wave systems comes in at $0.30 and up; offshore wind energy is between $0.15 to $0.24 per kWh; and solar power costs around $0.30 per kWh.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.