Second wind

It was probably inevitable that Japan's nuclear crisis would leave its mark on Hannover Messe, the world's biggest industrial trade fair.

Yet dreamers hoping to green tomorrow's energy supply consistently run into a common problem with renewable energies: Intermittency.

Although costs for renewables like solar and wind have come down in recent years, when the weather fluctuates, so do these power supplies, which can lead to big problems for energy operators.

With that in mind, Germany's Federal Ministry of Economics and Technology encouraged regions across the country to come up with solutions.

The result was a series of pilot projects. One of them, called the 'regenerative model region Harz' is on display at the Hannover Messe. It's run by the Fraunhofer Institute for Wind Energy and Energy System Technology.

"We want to prove that renewable energy sources can generate enough energy, and that they can also guarantee supply," Kurt Rohrig, deputy director of the Fraunhofer Institute, told Deutsche Welle.

Safety in numbers

They do this by combining the output from several generators to create a virtual power station that includes a wind farm, two block heating works and two biogas plants. The latter can be switched on as needed.

The project, which is also connected to other energy markets for buying and selling excess capacity, has already been running for two years, but Rohrig says it is yet to be taken seriously.

"We face the challenge of being accepted by other energy suppliers, and having them accept that renewable energy sources can supply markets and be considered a source of competition."

Electrics giant Siemens is involved in the communication side of the Fraunhofer project, providing what is known as a 'power bridge' which energy producers use to exchange information with the virtual power station.

Wind turbine manufacturer Enercon, which has chosen Hannover as the place to unveil its new E 101 prototype with 50 meters long turbine blades, is also a part of the Harz model region.

As is Solarfuel, a company which been working with the Fraunhofer Institute to create technology that enables wind energy to be stored underground.

"One possibility is that when wind energy is stored we create hydrogen and lead this hydrogen to a methanation plant, where with CO2 from a biogenic source we create methane, we call it renewable methane," Solarfuel sales representative Stephan Rieke explained.

This methane is then stored in huge underground cavities, to be used when there is not enough wind to create energy, or as fuel for vehicles powered by natural gas. Rieke says the great advantage is that it uses the existing natural gas pipeline network and storage facilities.

Increased investment

A disadvantage, however is that in converting wind to gas, as much as 40 percent of the energy is lost, or slightly less when using the warmth that is generated. But that, says Rieke, is better than not harvesting wind power at all. And he seems to be onto something.

Even before disaster struck at Japan's Fukushima plant, the German Renewable Energy Federation (BEE) demonstrated that sustainable power sources have a future.

This year German companies are expected to invest some four and a half billion euros ($ 6.3 billion) in production in the sector, and billions more in research and development.

Reporter: Insa Wrede/tkw
Editor: Nathan Witkop