Vattenfall has high hopes for wave power

STOCKHOLM, Sweden, Feb. 1 (UPI) -- Swedish energy giant Vattenfall says ocean energy -- such as wave power, salinity power or power from sea currents -- will become commercially viable as early as 2020.

The Swedes place their hopes in wave power, which they estimate could account for up 10 percent of Vattenfall's power generation in 2030.

The potential of wave power is huge. Vattenfall says it can ultimately produce around 250 TWh of green power, enough to supply up to 40 million people.

However, wave power is still an immature technology. Vattenfall is researching three different concepts -- Seabased, Wavebob and Pelamis.

The device developed by Swedish company Seabased has been tested since August 2009 off the Norwegian coast. The wave power facility is made up of several small buoys floating on the ocean surface that are linked via power cables to linear generators anchored to the seabed.

"The movement of the buoy is transferred directly to the generator with no intermediate mechanical gearing," Vattenfall says in a video clip presenting the concept. "The movement of the waves causes the translator to move vertically within the stator, thus converting the kinetic energy of the wave into electricity."

Wavebob is banking on a similar but much larger device.

Vattenfall teamed up with this Irish green energy company last year to research and develop commercial-scale ocean wave energy off Ireland's western coast in a joint venture called Tonn Energy ("Tonn" is Irish for "wave").

The Wavebob concept is based on a device made up of two buoys, one floating on, and the other below the water surface. An energy converter uses the motion between the two buoys and acts on hydraulic pistons that in turn pump oil to drive generators.

Each device is around 60 feet in diameter and nearly 300 feet high, and has a power output of around 1.5 MW, Vattenfall says.

The Wavebob is special in that it automatically adjusts its response to suit the prevailing wave climate and thus maximizes its power generation capacity. The company says this makes wave power more efficient, cheaper, easier to maintain and environmentally less intrusive.

The project is supported by the Irish government, which has invested in several clean energy companies, including Wavebob, to create 120,000 green jobs over the next few years.

An even larger device is the Pelamis, to be tested later this year off the Scottish coast. The 450-foot Pelamis looks a bit like a giant steel snake floating on the water. It rides the waves parallel to their direction and absorbs energy by restricting the motion of the bodies relative to each other by hydraulic rams.

All three concepts face similar barriers: They have to function in harsh seas with a minimum of maintenance, their environmental footprint needs to be as small as possible (Vattenfall is currently testing the devices' economic impact on marine animals), and they need to become commercially viable.

Ireland and Scotland, two countries with great wave power potentials, have indicated that they would be willing to subsidize this new technology.

Vattenfall says it wants to have a large-scale demo site online by 2015 and make the technology commercially feasibly by 2020 at the earliest.

State-owned Vattenfall has 33,000 employees and is active in Scandinavia and mainland Europe. It has set itself a goal of becoming carbon-neutral by 2050.