On the crest of a wave

Researchers at Lancaster University have joined the race to develop the world’s first offshore wave-powered electricity generator.

Following successful laboratory tests on a scale model, the university’s Frond WaveGenerator is to be commercially developed by the Northumberland-based Engineering Business (EB).

Unlike other ‘wet’ electricity generation projects already underway in the UK, which harness tidal power, the research team is hoping the Frond generator will become the first commercial device to capture energy from the waves.

Estimates suggest the UK has a wave resource capable of producing 50TW/h per year, over one seventh of the country’s annual electricity requirement, meaning wave generators could provide an important sustainable energy source.

EB has already developed the university’s Stingray Tidal Stream generator, which extracts energy from water flow and the velocity of tides. A prototype of this is currently undergoing tests in the Yell Sound, off the Shetland Islands.

The Frond system consists of a large, paddle-like collector surface, which floats on the end of a long lever. This stands vertical to the seabed at a height that just breaks the water’s surface. The lower end of the lever turns on a pivot and drives a hydraulic power take-off system housed in a base unit fixed to the sea bed.

When waves hit the paddle it oscillates back and forth like a frond of grass, moving the lever and allowing wave power to be harnessed by the base generator. As the paddle is able to move around, it can rotate to ensure that it always faces the prevailing direction of the waves.

Cash pledge

In the event of storm conditions, the whole system is able to react to limit the forces in the device, preventing it from being damaged, said Tony Trapp, managing director of EB, which has pledged £250,000 to further test Frond.

With this cash injection the team is looking to develop a prototype wave generator of approximately the same dimensions as Stingray.

‘The technology is in the early stages, but the prospect of turning it into a commercial enterprise is looking very attractive. The device depends upon oscillating movement, which is similar to the technology used for Stingray. However, Stingray’s arm is placed horizontally and not vertically to the seabed,’ said Trapp.

‘We have learned a lot through the deployment of Stingray, which we turned from a concept into a 180-tonne demonstrator working in a bay in the Shetland Islands within 12 months.

‘At present the Shetlands depend on power stations that are quite polluting for the islands’ current energy needs. We aim to help them by developing cleaner wave and tidal systems,’ he said.

Competitor Wavegen of Inverness is also developing a wave-powered generator with the help of funding from the DTI. This floats on the water’s surface and uses wave action to compress air in a tube, driving a turbine.

An on-shore version of the device, named Limpet, is currently feeding renewable energy directly into the grid at Portnahaven on Islay.