For Consumers, Hydrogen, Ocean Power, Renewables

Buoys plot to overthrow power regime

A wave-power device developed in a Melbourne university doubles output by turning two ways at once.

Floating somewhere in a barrel at Melbourne’s RMIT University is a device that may one day supply all the electricity Australia needs. Bobbing up and down off the coast, vast armies of similar machines will be deployed to turn out electricity, power electrolysers to produce hydrogen or turn seawater into drinkable stuff.

“We can supply enough electricity to supply the equivalent of Australia’s electricity production,” says Professor Xu Wang, lead researcher on a project that has drawn the attention of electrical engineers around the world since findings were published in Applied Energy in July.

The wave energy converter can produce twice the power of similar-sized conventional devices via a simple little trick where the rotor and stator of a turbine are connected to hydrodynamic fans that turn in opposite directions as the whole contraption floats on passing waves.

It’s something of a breakthrough, says Wang, whose team worked with researchers from Beihang University in China.

“The technology will be very cheap and easy to implement,” Wang tells EcoGeneration.

One at a time

The problem of harnessing energy from ocean swells as they approach the shore pivots on the synchronised operation of an array of sensors linked to generators to achieve optimal performance. Wang’s solution is different, in that each buoy is a discrete unit.

He describes them as similar to pistons in a car, where the up-and-down wave motion is transferred to a drive shaft, in this case a double turbine wheel.

He says “ship-sized” units, if successful, can operate as farms and be connected to underwater cables to send power to the shore.

The technology may also be used to power electrolysers at sea to manufacture hydrogen, he says, or perform desalination using the electricity and pressure generated via a pumping motion of the buoys.

On the horizon

Wang says wave energy is available 90% of the time on average and the potential power contained in offshore waves is “immense”.

The team is holding out for funding from industry and government to build a prototype suitable for testing in the ocean. A small-scale model is working in the laboratory.

Two turbine wheels, which are stacked on top of each other and rotate in opposite directions, are connected to a generator through shafts and a belt-pulley driven transmission system. The generator is placed inside a buoy above the waterline.

The prototype has been successfully tested at lab scale and the research team is keen to collaborate with industry partners to test a full-scale model, and work towards commercial viability.

“We know it works in our labs, so the next steps are to scale this technology up and test it in a tank or in real-life ocean conditions,” Wang says.

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