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Kiwi energy generator harnessing the power of ocean waves

On 5 June, which was World Environment Day, a group of energy scientists and engineers started up their prototype of a wave energy generator. It has been designed to harness the power of waves to make electricity in Evans Bay Wellington.

The prototype is a quarter of the size of the generators that the scientists eventually hope to make and it is the result of four years of intensive research and development. The most electricity the small wave-powered generator is capable of making is around 2 kW, this is enough to run two typical homes. However, the trial of the prototype will allow the project scientists and engineers to identify any bugs in the system and refine its design so they can make much bigger generators. The aim is to produce commercial wave-powered generators, each capable of producing at least 100 kW. These could supplement energy supplies for large cities or meet all the energy needs of remote communities such as offshore islands.

Dr John Huckerby, the director of Power Projects Ltd, says that wave power is extremely complex. “There is the up-and-down heave of the waves, the back-and-forth surge, and the pitch or rolling motion that surfers capture. The large hull of the device, sitting in the water rather like an iceberg, taps into components of the wave motion. A smaller ‘float’ at the sea surface pivots off the hull in response to the changing wave height. The relative motion between the two provides the energy for a hydraulic motor that actually produces the electricity.”

The wave energy generator is anchored to the seabed but can bob up and down on the ocean’s surface. This means that it is able to react to the wave motion but will not be damaged in storms. Over the past year, project scientists have trialled the prototype in the sea off Lyttelton Harbour in Christchurch. The Wellington trials are focused on the best way to anchor the wave-powered generator to the seabed as well as further improvements to the design.

Dr Huckerby says New Zealand is ideally situated for wave energy generation. “The country has a long coastline and is situated in the wind belt of the Roaring Forties. Big waves and swells roll in from a southwesterly direction, particularly in winter.”

The wave-powered generator has been developed by Wave Energy Technology New Zealand (WET-NZ) – a partnership between the Crown Research Institutes, Industrial Research Limited (IRL) and NIWA; and the Wellington power consultancy Power Projects Limited. The project is funded by the Foundation for Research, Science & Technology.

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