Bordering the Atlantic Ocean as well as the North Sea, Baltic Sea, Black Sea, and Mediterranean Sea, the European Union has roughly 138 000km of coastline. According to estimates, the total wave energy potential for all of these coastlines together is around 1 000 terawatt hours (TWh) per year – to put this figure into perspective, all EU countries together currently consume about 3 100 TWh of electricity per year.

However, wave and tidal energy still requires substantial research and development to reach its potential. For the CORES project, 13 partners from all over Europe came together to design, build and test components for ocean renewable energy systems.

The partners built each of the components separately and then brought them together in Cork (Ireland) for installation on a wave energy device called an ‘ocean energy buoy’, which was towed out into Galway Bay for three months of testing at sea.

Energy from waves and thin air

One of these components was an innovative oscillating water column system, constructed and now marketed by one of the partners in Portugal. The system basically consists of a steel box, in which water in enclosed. As waves go up and down, the water rises and falls inside the column and – like a large piston – pushes air in and out through a hole at the top of the column, where a turbine is installed. The turbine – connected to an electrical generator – starts spinning and thus generates electricity.

CORES used a turbine that spins in the same direction, regardless of which way the air is flowing, thanks to a self-rectification system.

“We developed an actively controlled air turbine,” explains Raymond Alcorn, who coordinated the project on behalf of the Hydraulics and Maritime Research Centre (HMRC) of the University College Cork. “A lot of research papers for maybe 15 years have postulated that this would be a more efficient way of doing things, but no one ever tried it out beyond lab testing. When we tested it in the ocean, it worked more efficiently than anything that we had ever seen.”

Test small, think big

At the time of the sea trial shortly before the end of the project in 2011, there was no cable to connect the systems on the buoy to the onshore power grid in Galway. So the project team developed an on-board system that emulates the grid in a sort of microgrid. As a result, they were able to use conventional technology that was designed to be plugged into the grid from the start – as opposed to doing a lot of engineering to adapt the system later.

This emulator, based on the knowledge gained from the CORES project, can now be put into test sites where three or four different wave or tidal energy devices can be plugged into it, providing an innovative kind of test facility offshore.

One such test facility is currently being built in Ireland. The Irish project team also recently constructed a hybrid power system based on exactly the same technology for a large American company.

“They came to Ireland for that particular microgrid expertise because we knew how to integrate many different sources such as wave, photovoltaic, etc. in one power system and balance the power flow,” says Alcorn, adding that these are just some examples of CORES's achievements.

“Thanks to the EU-funding, we were able to go out into Europe and get the best people to do each bit of the project. That was a massive benefit, and it really did show that no one country alone has everything,” he says.

Below picture of OE Buoy in Galway Docks during the research within FP7 CORES project