The gentle swaying of kelp forests belies the immense hydraulic pressures they've evolved to endure. The waves that crash over them transfer huge amounts of energy -- an average of 36kW/m with three-foot swells. Now, a green energy firm is banking on this sway to run arrays of Megawatt generators of the coast of Victoria.
The bioWAVE is mounted on the seafloor with a pivot hinge just up from the base. From this pivot, a trio of cylindrical blades extend to reach up to just below the surface -- generating power without spoiling to view from shore. These blades are buoyant so they can interact with both ocean swells -- as potential energy -- and horizontal wave motions below the surface -- as kinetic energy.
Since the hinge pivots, the blades can move constantly regardless of the precise direction of the waves -- like a piece of kelp. As the blades move about, they compress fluid in the base of the station that drives the unit's O-Drive hydraulic mechanism that converts the pressure into electricity. According to bioPower Systems, "Within each 250kW module, two hydraulic cylinders deliver high pressure fluid to a bank of accumulators which in turn supply a uniform flow to a hydraulic motor that is directly coupled to an electric generator" with the resulting charge sent back to shore and onto the grid. The drive is specifically designed to regulate the high-pressure input from wave actions into a standardized AC current.
The current 250kW prototype will work at depths up to 30 meters. If the testing in successful, a 1MW commercial-grade unit will be able to harvest energy as far down as 45 meters. So, what happens if a typhoon or tsunami comes rolling ashore? In the event of extreme waves, the system is engineered to lay flat against the seafloor, allowing the massive hydraulic pressures to pass over it harmlessly.
An array of these generators will soon be installed off the coast of Port Fairy, Victoria.The four-year pilot program will cost roughly $US14 million. Only $US10 million or so has currently been raised. [BioPower Energy Systems - Gizmag - Wave Power Wiki]