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Ships to provide cheap, clean wave power?  

A new dimension in the production of energy from wave power could revolutionise the way we are able to harvest and use electricity produced by the oceans, a conference in Boston has heard.

Ships that harvest wave energy and store it in batteries could one day generate cheaper electricity than today’s wave power devices. The ships would sail to an appropriate location, drop anchor and start producing and storing electricity, before returning to shore and feeding the stored power into the grid. This method of power harvesting would eliminate the current need for undersea cables linking the power generation modules and the shore. The current cost of these cables is more than $500,000 per kilometre.

Andre Sharon of Boston University and the Boston-based Fraunhofer Center for Manufacturing Innovation pointed out that the cost of cables is a significant percentage of the set-up cost of offshore wave power generation. They presented their idea for a possible ship to harvest wave power to the Clean Technology 2011 Conference and Expo. The ship, measuring 50 metres in length, is designed with buoys attached to the sides of the hull by arms which pivot up and down. As the waves pass the ship, the hull remains relatively still, allowing the movement of the buoys and the arms to drive a generator and then store up to 20 megawatt hours of power.

Sharon used 3D printing technology to produce a prototype and test it in a tank. Another element of using ships to produce wave power is that costs could be further reduced by removing the need for the ships to be very robust. At present, wave power generating devices have to be able to withstand very high seas as they are installed for the length of their operating lifespan, adding significantly to their cost. Wave power ships could be kept in port during bad weather, reducing the need to build them to cope with any conditions.

The team calculates that the ships could produce power for as little as $0.15 per kilowatt-hour, putting it on a par with offshore wind power and making it significantly cheaper than current wave power systems.

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