Helsinki -- The flap was the weirdo in wave power two years ago, admits John Liljelund, CEO of AW-Energy, the designer of the WaveRoller wave power machine. But the concept in the still-emerging niche market is gaining momentum.

The company -- which has designed a large underwater flap that undulates with waves and pushes against a hydraulic ram to generate pressure -- has operated a 10-kilowatt-capable prototype since 2007. In 2011, it will take the next step and install a 300-kilowatt device under a 3-million-Euro grant off the coast of Portugal, and follow that up with a "pre-commercial" system in 2014 or so that will be capable of generating 1.5 megawatts if the test results and ever-crucial financing come through.

After that, ideally, will come commercial versions of the system that can generate two to three megawatts and produce power at around 20 Euro cents a kilowatt hour, which can potentially make the system commercially viable when wave power incentives in Europe and other regions are added.

"Twelve to 15 cents is the aspirational goal," he said.

While that still means an uphill climb for wave power, AW-Energy -- which emerged in Finland but has since moved its executive offices to Silicon Valley -- at least can point to a growing acceptance of the concept. While hydroelectric power is a mainstay in the electricity business, six other water power concepts -- wave, tidal, micro hydro, osmotic pressure gradients, ocean thermal, and oceanic air conditioning -- are currently angling to move toward acceptance.

"Two years ago, we were the strange flap company. Now it is a category. Aquamarine has something quite similar," he said. "We [flaps as a concept] were in the top three in [a recently conducted] PG&E study."

The change comes in part from problems that have surfaced with other wave concepts and increased recognition for the benefits of flaps, he said.

First, the benefits. The WaveRoller will operate close to shore. Near-shore waves generate 20.6 kilowatt hours per meter of waves per year, he said. That's lower than the 34.1 kilowatt hours per wave meter per year for offshore waves. The energy that can be harvested feasibly from near-shore waves, however, comes to 17.7 kilowatt hours a year, compared to 23.3 kilowatt hours a year for offshore waves. Thus, on a practical level, near-shore wave devices can produce nearly as much power.

Near-shore wave devices, however, are far easier to maintain and install, he argues. A three-flap WaveRoller system sits on an integrated platform that can be submerged and brought to the surface with ballast systems, similar to how marine engineers submerge and install other equipment. Bearings, rams and other components get replaced every three to five years, but the platform will operate for 20 years, he said.  

The WaveRoller will sit in water only eight to twelve meters deep. The flaps will undulate every nine to 12 seconds.

"There is only one moving part exposed to the weather, the hinge," he said.

Additionally, near-shore devices require shorter connections. A transmission cable may only have to go 300 meters to 500 meters to connect to them. Although the flaps on the WaveRoller are currently square, the company is studying hydrodynamics to adjust the shape, similar to how wind turbine manufacturers tinker with blade designs. To increase power, the flaps will also get wider and longer.

Meanwhile, competitive devices have not fared well. Pelamis Wave Power, one of the more publicized companies, planted three of its sea-snake-like devices off the coast of Portugal in 2008. Technical problems grounded the prototypes soon afterwards, and the company subsequently jettisoned its CEO. Other wave concepts like the Wave Dragon have remained in the testing stages.

The biggest problems facing wave power? The industry as a whole has to regain its credibility with investors. It also has to show that all of the parts will work together.

"The inverter [which sits under water]. That is my biggest nightmare right there," he said.