A wave of energy

Wave power is gaining traction as a new commercially viable net zero energy solution.

If you happened to be by the coast of Aguçadoura, Portugal, in February, you might have seen an intriguing sight: tugs towing rather large, yellow bulbous objects with cylinders protruding out of opposite ends out to sea. Designed by CorPower, these unusual objects are wave energy converters. One day, they may play a key role in delivering clean, renewable energy on a commercial scale.

Capturing energy from waves

The earliest known wave energy converter patent dates back to 1799, but it wasn’t until the early 2000s that wave energy converts began to see the development and investment needed for commercial-scale application. Wave energy “is at such an innovative stage, it’s quite exciting,” says Dr Shona Pennock, a research associate in marine energy with the University of Edinburgh and technical advisor with EVOLVE, a transnational marine renewable energy partnership between research institutions, technology developers, and industry.

Wave energy converters can take many forms, each harnessing wave motion differently. “CorPower’s wave energy converters are like big floating buoys fixed to the seafloor that convert vertical movement into rotational movement to generate electricity,” explains Pennock. “Another type of device, which has just been deployed by Mocean Energy in Orkney [Scotland], is like a hinged raft. Whenever the device moves with the waves, a fluid inside flows between the two sections, generating electricity,” Pennock adds. 

Another example comes from Eni, Politecnico di Torino, and Wave for Energy s.r.l.’s Inertial Sea Wave Energy Converter, a steel hull anchored to the seafloor in the Strait of Sicily that swivels in response to metocean conditions. Meanwhile, in Australia, Wave Swell Energy Ltd has been testing a converter that harnesses an artificial blowhole to force air up and past a turbine to generate electricity.

Most commercially viable wave energy converter systems are still in the testing stage and often in relatively sheltered waters. The CorPower site in Portugal will be one of the few located further offshore. “It will be interesting to see how those devices do when they encounter much more intense wave climates,” says Pennock.

CorPower Ocean’s first commercial-scale C4 wave energy converter (Credit: CorPower Ocean)

A portfolio of energy generation

When it comes to generating electricity from the ocean, wind farms have so far dominated the conversation. With wind turbines getting larger and generating more energy than ever, is wave energy necessary? 

“It’s all about balance. We’re not saying wave is the solution. We’re saying it could form a really useful part of our net zero future,” Pennock explains.

Research by EVOLVE exploring the viability of wave and tidal energy in Great Britain, Ireland, and Portugal suggests wave energy resources of 24.8 GW in Great Britain, 18.8 GW in Ireland, and 15.5 GW in Portugal. “It was really interesting to see the potential [of wave energy] across these three different regions,” says Pennock, highlighting that the ideal mix of energy generation technologies will vary depending on the prevailing conditions experienced in a location.

Crucially, including wave energy in clean energy portfolios isn’t just about the amount of energy delivered; it’s about when that energy is delivered. “There are times when we have low wind resources, but we still wave resources available and vice versa,” explains Pennock. “We also find that there is a lot more wave energy generation potential in the winter months, which is correlated to when we have high demand,” Pennock explains, adding that solar generation, which is more common in countries like Portugal than Great Britain or Ireland, tends to decline during the winter months.”

“With a more diverse mix of renewables, you could probably meet your energy demands better and generate that energy when you need it without having to rely on storage and then incurring the losses associated with storing electricity,” says Pennock.

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Dr Sam Andrews is a marine ecologist and science writer