New wave of ocean energy to be trialed off the coast of Australia
By Ben Coxworth
December 5, 2011
Anyone who has ever been scuba diving in a bull kelp forest will tell you - the stuff does not stand still. The marine aquatic plant consists of a long skinny-but-tough stem (or stipe) that is anchored to the sea floor and topped with a hollow float, from which a number of "leaves" (or blades) extend to the surface. The result is a seaweed that extends vertically up through the water column, continuously swaying back and forth with the surging waves. The researchers at Australia's BioPower Systems evidently looked at that kelp, and thought, "what if we could use that swaying action to generate power?" The result was their envisioned bioWAVE system, which could soon become a reality, thanks to a just-announced AUD$5 million (US$5.1 million) grant from the Victorian Minister for Energy and Resources.
At the base of each bioWAVE system would be a triangular foundation, keeping it anchored to the sea floor. Extending up from the middle of that foundation would be a central column, topped with multiple blades - these would actually be more like a combination of the kelp's blades and floats, as they would be cylindrical, buoyant structures that just reach to the surface. The column would join the foundation via a hinged pivot, allowing it to bend or swivel in any direction.
Wave action (both at the surface and below) would catch the blades and push them back and forth, in turn causing the column to move back and forth relative to the foundation. This movement would pressurize fluid within an integrated hydraulic power conversion module, known as an O-Drive. The movement of that fluid would spin a generator, converting the kinetic energy of the waves into electricity, which would then be delivered to shore via subsea cables. The video below illustrates how the system would work.
According to BioPower, each system could be installed in the ocean using standard vessels without any special equipment - all components would be towed and then sunk into place. The O-Drive would be easily detached and replaced, so the whole assembly wouldn't need to be pulled out of the water for servicing. Additionally, the system would automatically detect unusually large swells, at which point it would flood the blades, causing them to lie down flat against the seabed for protection - this should allow for lighter, less expensive construction materials, as the blades wouldn't need to be designed to take the full force of violent conditions.
As an added bonus, unlike many other wave power systems, very little hardware would be visible above the surface. This should help with public acceptance of the technology.
The $5 million grant will go towards an AUD$14 million (US$14,365,000) four-year pilot demonstration unit, to be installed at a grid-connected site near Port Fairy, Victoria. Some other funds have already been obtained, leaving $3.6 million still to be raised.
While the 250-kilowatt pilot system would operate in 30-meter (98.5-foot)-deep waters, the planned 1-megawatt commercial-scale units would work at depths of 40-45 meters (131-148 feet), each one running four O-Drives in parallel. A number of such units could be located in one area where the depth and wave action are ideal, creating "wave farms."
We wish BioPower luck with the endeavor, and will be watching its progress with interest.
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