Making waves work: wave energy trials underway in Wellington
A uniquely ‘Kiwi’ wave energy generator is harnessing the power of waves in Evans Bay Wellington.
The device 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 (PPL).
The generator in Evans Bay is an experimental prototype. At a quarter of full-size, it is the product of four years of intensive research and development, funded by the Foundation for Research, Science & Technology.
The experimental generator is capable of a peak output of only around 2 kW of electricity (enough to run two typical homes) but is allowing the project scientists and engineers to refine its design so that it can be scaled up in size. The consortium’s ultimate aim is to produce commercial devices, each capable of producing at least 100 kW, that could supplement energy supplies for large cities or meet all the energy needs of remote communities (eg, offshore islands).
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 by a slack mooring so that it is able to react to the wave motion but will not be damaged in storms. Over the past year, project scientists trialled the prototype in the sea off Lyttelton Harbour, Christchurch. The Wellington trials are focused principally on the mooring technology as well as incremental improvements to the design.
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.