Residents of the Scottish town called Invergordon are about to witness the first sea trials of a power-generating buoy device called, aptly enough, the PowerBuoy PB150. Developed by Ocean Power Technologies, Inc., the new generator has a capacity of 150 kW. It creators foresee ocean-based farms full of the devices that will generate hundreds of megawatts.A 10-MW power station would occupy only approximately 30 acres (0.125 km2) of ocean space. The company figures the cost of generated power to 15 cents/kW-hr, based on costs assuming production levels of 400 PowerBuoys annually.
The trial site is approximately 33 nautical miles from Invergordon. The company has already installed a smaller PB40 system off Oahu, Hawaii, which has operated since December 2009 and which is now connected to the utility grid there.
The buoys generate power from the rising and falling of the waves off shore which cause the buoys to move freely up and down. The resultant mechanical stroking is converted via a power take-off to drive an electrical generator. The company has not released details about the make-up of this power take-off assembly.
The generated power is transmitted ashore via an underwater power cable. Sensors on the PowerBuoy continuously monitor the performance of the various subsystems and surrounding ocean environment. In the event of large oncoming waves, the system automatically locks-up and ceases power production. When the wave heights return to normal, the system unlocks and recommences energy conversion and transmission of the electrical power ashore.
Buoys get moored to the sea floor using a conventional mooring system get hauled out and put in place using conventional marine vessels.