Offshore device is hydropower’s next wave

An ocean wave power device could provide up to three times more electricity than those close to the shore, its developer believes. The generator, which is being developed by Irish company Wavebob, is similar in design to a heaving buoy and produces energy by moving up and down with the waves.

An array of around 200 devices, each generating around 1MW, could be deployed far out in the North Atlantic in a similar way to an offshore wind farm, according to Wavebob managing director William Dick. This would generate much more electricity than shore-based or near-shore devices. ‘Much less power is available inshore because waves lose energy as they enter shallow water,’ he said.

The device floats mainly below the surface and is tethered to the seabed by weighted mooring lines. As it moves up and down like a buoy, it pulls against this weight – either the seabed or a massive plate – producing energy that is harnessed by a hydraulic generator.

‘It can go into very energetic seas, such as those off the north coast of Scotland and Ireland,’ said Dick. ‘Our aim is to develop a device that produces power at least as well as an offshore wind turbine, and we think we are within that envelope.’

Most wave power devices are built to match the most common wave frequency in their area of sea, and when the weather changes, increasing or decreasing wave heights, they become less efficient. But Wavebob’s device can match changing wave frequencies, using on-board sensors and controls to retune itself.

The device can also be remotely controlled in extreme weather conditions, such as the 35m waves occasionally seen in the North Atlantic. ‘If you hear that a storm is coming you can dial it up and tell it to detune itself completely,’ Dick said.

Wavebob is jointly owned by Dick and Norwegian firm Fred Olsen, owner of Harland and Wolff. Around £1m has been invested in the project, with the Irish government providing some financial backing.