Pictures of the Future    Spring 2007

Tapping the Sun and Moon

Dr. Jochen Weilepp has a vision: anywhere from 10,000 to 100,000 wave power plants operating worldwide. Weilepp, head of the Wave Energy department at Voith Siemens Hydro Power Generation (VSH), is working with his team on exploiting the power of waves, which is still nearly untapped. The team identifies, assesses, develops and markets promising new hydropower technologies.

World energy demand continues to be met mainly by non-renewable resources such as oil, coal, gas and nuclear power. These natural sources will be exhausted in the foreseeable future, however. The available alternatives are energy from water, wind, the sun, and biomass, as well as geothermal power. Hydroelectric power plants now generate about 18 % of the world’s electricity. More than a third of that hydroelectric power is produced with turbines and generators from VSH.

Hydropower offers many advantages. It’s renewable, it’s generated without producing greenhouse gas emissions, and the reservoirs created by dams can be used for recreation. The reservoirs also provide drinking water and irrigation, while the dams help to prevent flooding and facilitate navigation of rivers. There are drawbacks, however. One is that building big hydroelectric plants often disrupts the natural environment, in some cases having a major impact on residents nearby. "We’re very aware of our obligations in this regard. That’s why we consistently work to achieve solutions that are socially and environmentally responsible," says Dr. Hubert Lienhard, VSH board spokesperson and a member of the board of management of Voith AG.

Everything from Dams to Waves. Voith Siemens Hydro’s core business is mechanical and electrical equipment for hydroelectric plants. Established in 2000, VSH is headquartered in Heidenheim, Germany and employs 2,500 people worldwide. Voith holds 65 % of the joint venture, and Siemens controls the remaining 35 %. "We don’t just manufacture equipment; we’re also engaged in research, development, and consulting services," says Dr. Siegbert Etter, head of VSH Corporate Technology. "In other words, we’re a full-range supplier that does everything but dam construction, which is handled by civil engineers." Roughly ten companies operate in the same sector as VSH, which holds approximately 20 % of the global hydroelectric market. New orders in 2006 totaled 720 mill. €, which makes the company number two in the market.

Although everyone associates hydroelectric power with dams, few think of it in terms of generating energy from the sea. "In theory, the potential of the sea is around 1.8 TW, with 1 TW of that from wave energy alone," Weilepp says. "By way of comparison, 1 TW equals the output of 700 major nuclear power plants."

The wider a wave power plant is, the greater its output will be. Indeed, a good location can yield an annual average of about 30 kW/m. No commercial wave power plants have been built yet, but there are roughly 100 concepts for their realization. "Less than ten of these will reach the market within three years," Etter predicts. That’s because making a new form of energy feasible on a large scale is a very complex undertaking.

Still, Weilepp is confident that "our breakwater technology will be among those systems that make it to market." Opting for oscillating water column technology, VSH acquired the Scottish company Wavegen in May 2005. The company has operated the world’s first oscillating water column power plant on the island of Islay (see  box) since 2000. A key component of the facility is the Wells turbine, which always turns in the same direction, regardless of the direction of flow. This eliminates the constant acceleration and braking (and resulting energy loss) that occurs when the direction is changed. It’s like birds flapping their wings to achieve constant forward motion—and it’s said that birds even inspired Alan Wells, the turbine’s inventor.

The Islay facility provides electricity to about 50 households on the island. That may not be much, but the Scottish wave power plant is still the only one in the world that’s continuously supplying power to the grid. "It’s the ideal environment for us to gain a better understanding of the technology and processes involved, and to test them under everyday conditions," says David Gibb, managing director of Wavegen. This testing has enabled Wavegen experts to improve the unit’s efficiency. Now they’re planning the first major application of the technology, by studying the possibilities for a project in Scotland in cooperation with RWE’s British subsidiary, npower. VSH and energy supplier EnBW are also currently searching for a suitable location for a wave power plant on Germany’s North Sea coast. The facility is to have a rated output of around 250 kW.

Power Plants that Protect Harbors. Wavegen’s facility is also known as a "Limpet." The reason for this is that like limpets (mollusks), the wave power plant also "sticks" to rocks. The name also stands for "Land Installed Marine Powered Energy Transformer." The facility’s location on the coast offers many benefits. It’s easily accessible, easy to service and can be linked to the power grid without difficulty. What’s more, wave power plants can be incorporated into breakwaters, which harbors are already equipped with, thus substantially cutting costs. A single structure could therefore perform two functions, and the costs could be split. The harbor walls would include small air chambers containing several small turbines, which the team at Wavegen is currently testing at the Limpet facility in Scotland. Plans have also been developed for a new harbor to be built in northern Spain.

"We also recently began tapping energy from the moon, along with energy from the sun," says Etter. "Energy from the sea is divided into wave and tidal energy," he explains. "The first is created by the power of the sun, the second comes from the moon." There are several technological approaches for harnessing tidal energy. Conventional tidal plants require a dam, but tidal-flow power plants use several underwater machines placed under a bridge. "You could say it’s something like an ‘underwater wind park’," Etter says. In a joint venture with a Korean company, Voith Siemens Hydro is planning to develop and test such a power plant for a major project in Korea that will include between 500 and 1,000 turbines. The project is still in the planning stage, however.

Power generation from the sea has advanced dramatically in the last five years, but many issues remain to be clarified, such as which approach for harnessing wave and tidal energy is most effective and least costly. There’s also the question of how other power generation technologies will develop. One thing is certain, however. It will be a long time before Weilepp’s vision of 10,000 to 100,000 wave power plants becomes reality. Nevertheless, the first steps in this direction have now been taken.
                                                                                                                    Gitta Rohling