'Fleets' of new wave-energy device could power thousands of homes

An international team of engineers has developed a durable, low-cost device that could be deployed in fleets around the coast to harness wave energy.

The project's engineers, at the Universities of Edinburgh, Trento and Bologna, and the Sant’Anna School of Advanced Studies in Pisa, Italy, have developed and tested the device, known as the Dielectric Elastomer Generator (DEG).

The 15m diameter generator uses flexible rubber membranes and is designed to fit on top of a vertical tube in the sea. As waves pass the tube, the water inside pushes trapped air above to inflate and deflate the generator on top. As the membrane inflates, a voltage is generated. The voltage increases as the membrane deflates, generating electricity. In a commercial installation, this would be carried to shore via underwater cables.

The DEG costs less than conventional designs, is made of durable materials and has fewer moving parts, the researchers said. They claimed that “fleets” of easily maintainable devices could be installed around Scotland within decades.

“Wave energy is a potentially valuable resource around Scotland's coastline, and developing systems that harness this could play a valuable role in producing clean energy for future generations,” said Professor David Ingram from the University of Edinburgh.

The technology could fit into existing infrastructure, he told Professional Engineering. "You could replace the air turbines and existing oscillating water columns with the dielectric rubber membrane and so you’re doing away with a fairly complex piece of electro-mechanical equipment and replacing it with a sheet of rubber and a fairly sophisticated set of power electronics, so it should be easy to maintain."

Researchers tested a scaled-down version of the system at the FloWave facility at the University of Edinburgh, a 25m-wide tank that reproduces combinations of ocean waves and currents. Experiments reportedly showed that a full-sized device could generate 500kWh, enough electricity for about 100 homes. The system could replace conventional designs involving complex moving parts, the team said.

"I think scaling up the technology... to something that could be used in a pilot scale or demonstration scale project is not going to be too tricky for us, that is something that will probably take two or three years," said Professor Ingram. "The difficulty is probably getting the civil work done... so you can install something like that. You are probably looking at under 10 years to see this in larger scale deployments in the ocean."

The research was was supported by the European Union Horizon 2020 programme and Wave Energy Scotland. It was published in Proceedings of the Royal Society A.