Innovation & Design

AW Energy Gets Power from the Ocean Floor


To get to Ilkka Homanen's office, nestled in a technopark in Espoo, Finland, visitors have to cross a small entry hall featuring one large object: a sturdy-looking one square meter (nearly 11 square-foot) plastic plate, with a hydraulic contraption attached to it, leaning against the wall.

It's a prototype of the plates that the Homanen-led start-up, AW Energy, is installing in Peniche, Portugal, about 100 miles up the Atlantic coast from Lisbon. They're made of a combination of steel and plastic, and in the coming months they should start producing electric power—hydrokinetic power, to be precise.

The plates will be anchored on the ocean floor near the shore, at a depth of a dozen meters. They are designed to capture the back-and-forth motion of underwater swells. The movement produces kinetic energy, which is collected by a piston pump and converted to electricity by more conventional generator systems onshore.

EUREKA MOMENT. It may sound trivial, but it's not. With the prices of oil, natural gas, and coal soaring, renewable sources of energy are attracting new attention and becoming more cost-competitive. While recently wind and photovoltaic power, and ethanol, have captured the headlines, Homanen believes that AWE has spotted another untapped reservoir of dependable, clean, renewable power: shallow-water bottom waves. "Additional benefit: our system is sunken, therefore invisible," he adds.

The story, according to AWE's official company lore, goes as follows: Rauno Koivusaari, the company's founder, is a professional diver who usually works on subsurface constructions such as cable installations. In the mid-1990s, as he was exploring a shipwreck, he almost got hit by a metal bulkhead door that was flapping slowly back and forth, pushed by the underwater waves. This was Koivusaari's own Newton-and-the-apple moment: Could that power be harnessed, he started wondering?

Fast-forward a dozen years, after several tests by Fortum (Finland's biggest energy conglomerate) and by other companies, and trials at the EU-financed European Marine Energy Center in the Orkney Islands, Scotland, and now AW Energy is preparing to produce electricity by harnessing that wave power.

LOW IMPACT. Underwater waves have a different motion structure from surface waves: they are more horizontal, regular, and predictable. In Peniche, 77% of the time they come from the same direction. That's where the plates—called WaveRollers—will be anchored.

"They will oscillate back and forth on an axle following the movement of the waves," explains Homanen. A hydraulic pump will capture the energy and pass it on to a generator "hosted in a small cabin onshore—the only visible part of the system," he adds. The cabin will also shelter the equipment needed to connect to the grid. Combine a number of WaveRoller modules and you have a full plant.

By the time the technology is ready for full-scale commercialization in a couple of years, the WaveRoller approach is expected to produce electricity at a cost of between €30 and €50 per megawatt/hour; "on par with wind and nuclear and competitive with more traditional energy sources," says Homanen.

EAST RIVER ENERGY. AWE is not the only startup trying to capitalize on some of the gigantic potential represented by near-shore wave power. The Scottish company Ocean Power Delivery has developed a floating system that converts wave motion into pneumatic pressure to propel energy-producing turbines. It looks like a long metal snake floating a few miles off the coast and is also being commissioned, coincidentally, in Portugal, north of Peniche.

Britain's Wavegen has designed an onshore mechanism that uses wave surges to compress air into a concrete chamber, which in turn drives a generator. Verdant Power in Arlington, Va., is installing underwater turbines that will move with the tides in the East River in New York.

Some of the advantages of the WaveRoller are evident. With the exception of the generator, the entire plant lies beneath the surface of the water and is therefore invisible, avoiding the "not-in-my-backyard" syndrome (witness the uproar about the offshore wind farm project in Cape Cod and a similar controversy in the Jura mountains of Switzerland).

LESS STRESS. In Peniche, everyone's in favor of the farm: politicians, people, marine biologists—even fishermen. Says Homanen, "They said that the WaveRollers may become some sort of sanctuary for the fish, giving them a protected area against overfishing." And because the installation is typically at 7 to 15 meters of depth, boats can sail over it without difficulty.

The power generated by bottom waves fluctuates considerably less than that of surface waves or wind, providing a more dependable source of energy. Also, the equipment is submitted to less stress. "Surface systems need to be designed to survive the most severe conditions; onshore technology also gets lots of damage because of storms," explains Homanen. "But down at the bottom the conditions are softer, and the WaveRoller is designed to go flat if a big wave hits it, minimizing potential damages."

VEGETABLE OIL. Still, AWE is installing metal and hydraulic equipment in salty water, so maintenance (and removing barnacles and other marine growth) will probably cost more than it would for, say, a wind turbine. "True, but while we maintain one plate, the others nearby can continue to produce energy. We don't need to shut down the whole plant," Homanen explains.

Most importantly, however, the WaveRoller doesn't produce any noise and moves with the water, "so we don't harm or modify the natural movement of nature." Homanen acknowledges that, "Every construction put on sea obviously has an impact." But AWE seems to have genuinely tried to minimize it. Even the oil used for the hydraulics will be of vegetable origin.


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