Waves To Wire

For the past few years engineering firms have been testing hulking steel wave-energy devices in the wild waters off the Scottish islands, Australia, and Portugal. Machines such as Aquamarine Power’s clamshell-style Oyster, Carnegie Wave Energy’s lollipop-shaped CETO, and Pelamis’ sea-snake-like P2 are set to generate electricity at a competitive cost in the next few years, according to their inventors.

The devices generally work by harnessing wave energy to pump water through electric turbines. But now companies including the Dutch engineering firm SBM and the chemical maker Wacker Chemie are developing wave-energy devices from electroactive polymers (EAPs). They are betting this chemical approach will blow the steel devices out of the water.

“By using EAPs, both the installation and maintenance costs of ocean wave plants can be reduced significantly compared with today’s hydraulic technologies,” says Martin Grunwald, head of wave power research at Wacker.

EAPs have yet to undergo extensive testing in the oceans, and that could uncover some problems, experts say. But if either technology actually goes commercial, the business opportunity is huge. Electricity that is technically recoverable from wave energy could more than meet the world’s energy requirements, according to a United Nations report. And the developers of these technologies are expecting their machines to compete—in efficiency and cost—with established energy sources.

Surrounded by water, the U.K. has become the global hub for wave-energy development. The Carbon Trust, a British nonprofit, estimates that the sector could create 68,000 jobs in the country by 2050. Around the world, about 80 companies are pursuing various wave and tidal energy technologies.

Munich-based Wacker’s wave-energy-capturing device is based on high-purity silicone films sandwiched between layers of activated carbon, which act as electrodes. When hit by a wave, the silicone surface stretches, causing the electrical charge on the surface to increase. The elastomer is then short-circuited, the electricity is harvested, and the film moves back to its original shape for the cycle to begin again.

Multiple layers of silicone and activated carbon could be stacked to create a device about a cubic meter in size, Wacker says. The firm has teamed up with four technology companies and two universities in Germany in a project that has received $2.6 million in funding from the German government. The goal is a demonstration device by the end of 2014.

Wacker and its partners have yet to settle on the design of their device. They are considering a buoy, anchored to the ocean floor, that contains a stack of thousands of sheets of silicone and activated carbon. Every three to 10 seconds, the stack would be activated by the movement of the waves.

The firm is testing a manufacturing process for making the high-purity silicone films in Burghausen, Germany. Film produced in the pilot facility is between 20 and 100 µm thick, Grunwald says.

Fellow German company Bayer is developing a polyurethane-based wave-energy device with the help of its Silicon Valley-based subsidiary Artificial Muscle, which already sells silicone-based EAPs to the portable electronics industry. The companies are enthusiastic, but acknowledge the hurdles ahead. “We have done extensive testing at lab scale and are still facing technical and commercial challenges. It may take a few more years until we will see this in a commercial setting,” says Dirk Schapeler, Artificial Muscle’s chief executive officer.

SBM is another heavyweight company in EAP wave energy. The firm’s S3 EAP wave convertor features a tube designed to float under the ocean surface. SBM has secured funding from the French government to test a full-scale version within a consortium that includes French research institute IFREMER. The institute is also participating in a European Union-funded initiative offering wave-energy firms free use of 45 marine research facilities across Europe.

SBM acknowledges that it’s uncovered “challenges” during its scale-up of the technology, without disclosing details. The consortium plans to test S3 in French waters in 2014–15. But like Bayer, it is finding the concept to be challenging. SBM is seeking financial partners for commercialization.

Although EAP firms are at the testing stage, they haven’t yet completed tests in extreme ocean conditions, something that many developers of hydraulic devices have done, says Warwick Grigor, research director for the investment bank Canaccord Genuity, which covers the sector. With uncertainties about EAP technology still apparent, Grigor is backing hydraulic wave devices to be the first to reach the market.

Because extensive testing hasn’t been completed, Wacker and other EAP developers don’t yet know the operating costs for their devices. Wacker’s German consortium is targeting 50% efficiency for converting mechanical energy to electrical energy. If the partners can achieve this rate, the technology is scalable. “The electrical current from one individual layer is minimal, but when it is multiplied by a thousand or more, it soon adds up,” says Istvan Denes, an engineer at Bosch, one of Wacker’s partners.

Hydraulic wave technology firms claim to have a better handle on the unit cost of the energy their devices will generate. Carnegie’s CETO technology, which features an 11-meter-diameter underwater buoy tethered to hydraulics, gets particularly high marks. “Depending on whom you ask, CETO will be cost competitive with traditional energy sources, but only once operating at similar scale of hundreds of megawatts,” Grigor says. CETO’s system has the added benefit of being able to desalinate water.

But the Achilles’ heel for hydraulic technologies is maintenance costs. Carnegie, for example, forecasts that 20–40% of its total operating cost will be for device maintenance. Wacker’s EAP materials, on the other hand, have been designed to withstand 10 million cycles without maintenance. “This has to stay in the water for 20 years,” Grunwald says.

Although they face challenges, developers of EAP wave devices are confident their approach will work. “We do strongly believe in this concept. I am convinced that it will get the go-ahead and be successful,” Grunwald says.