Waving hello to electricity...plus fresh water

A wave energy system that sits on the seabed could simultaneously generate electricity and produce fresh water, according to the UK company commercialising the technology.

The Australian-developed CETO system has just been bought for £5m by UK investment company, Renewable Energy Holdings (REH).

The CETO unit is anchored to the seabed at a depth of between 10–25m and coupled to a proprietary pump system which supplies high-pressure seawater to a conventional on-shore generator.

As waves moves over the unit, they depress a disk on top of the box and transmit a force to the pump, which delivers water at almost 70 bar. It is carried ashore in a 125mm diameter pipe to a turbine, which produces the electricity. Each CETO unit could potentially produce 100kW of power.

The water can also be pumped through a reverse osmosis filter on the shore, which produces desalinated water. REH operations director Jannie Retief said: ‘The fresh water part was something the Australians got really excited about, whereas in Europe everyone is much more interested in the renewable energy idea.’

The unit is equipped with sensors that monitor the size, speed and frequency of the waves and use algorithms to optimise the pump’s performance. In the long-term, the objective is to have multiple units in place as a wave energy farm, which could produce commercial quantities of electricity plus large quantities of fresh water.

The system is currently undergoing trials in Australia, after which REH will be looking to find a UK site for larger scale testing next year. This would involve the construction of a mini-farm of around 10 CETO units, which could produce a combined 1MW of power.

REH says a 5MW system of around 50 units, would cost £6.5m to install and £250,000 a year to operate, but could work out to be more than twice as profitable as a similar sized wind power project.