GERMAN "VORSPRUNG durch Technik" (advancement through technology) has done it again. German chancellor Angela Merkel has laid the foundation for a "milestone" renewable energy plant that answers the big question surrounding wind energy: what happens when it isn't windy?

The €21 million "hybrid" plant was unveiled last week and is scheduled join the grid next year in the Uckermark region of Brandenburg near Berlin.

The station's three windmills generate energy for the region but, with a total capacity of six megawatts, are likely to produce more electricity than is needed at any one time.

The excess electricity is fed into a 500 kilowatt (kW) electroliser to produce hydrogen that is stored onsite. When needed - when the wind stops blowing, for instance - the stored hydrogen can be tapped, mixed with biogas produced at the site from local corn, and fed into the facility's two traditional power stations of 350kW capacity.

The electricity and heat produced in a process called "co-generation" can be piped to households and businesses in the region.

Excess hydrogen can be sold to local hydrogen providers for hydrogen-driven cars and buses.

Enertrag, the company building the plant, hopes the technology will solve the traditional problem of wind power: that it produces too much or too little energy.

The plant will incorporate an innovative energy monitor to fine-tune the production of energy to required levels and minimise waste - a reported first in the renewable sector.

All that, and it is carbon neutral into the bargain.

"With our hybrid energy station, wind energy can be stored in an economical fashion," says Jörg Müller, chairman and founder of Enertrag.

"We are closing the gap between renewable energy and energy-efficient mobility:

only hydrogen produced regeneratively creates sustainable CO2-neutral mobility."

Hydrogen-fuelled vehicles generate no greenhouse gases in exhaust fumes, but the hydrogen they use is produced from fossil fuels, generating large quantities of carbon dioxide.

The hybrid plant's "clean" hydrogen fuel has caught the attention of French petrochemicals giant Total. It has come on board as a partner in the project, hoping to a get headstart on competitors. "This project is so interesting for us because, as an energy provider, we know that oil energy sources won't be sufficient to cover the rising energy demands," says Patrick Schnell, head of Total Germany.

Merkel welcomed the station, being built 30km (18.6 miles) from where she grew up, as a "qualitative leap with an energy plant the likes of which we have never seen".

"In my view it's a solution for the future, not just for hybrid cars but for hybrid energy stations that make full use of renewable energies," she says.

Some 20,000 windmills dot the German countryside - more than any other European country.

Germany is a leading exporter of green energy technologies, a position the federal government hopes will be secured with the new hybrid technology.

Last year German companies sold wind energy technology to the value of €8.5 billion, a jump of 12 per cent on 2007 - more than 80 per cent of which was for export. At home, the hybrid technology may help Germany reach its 2020 goal of 20 per cent energy savings and 20 per cent renewable energy usage.

"When I look back to over 10 years ago when I was environment minister I would have considered such a goal utopian," says Merkel. "At the time we thought the 20 per cent regenerative electricity share alone was very high. Today I really think I can say that we will reach that goal."

Some renewable energy experts have expressed doubts that the electrolysis will be as effective as planned and warn that the technology is a long way from being market-ready. The storage of the hydrogen and returning it to the form of electricity, even with the latest technology, results in huge losses of energy.

"The technology is very elaborate and very expensive," says Dr Peter Schäfer of the Jülich research centre, which operated a similar hydrogen storage system powered by solar cells.

"In our project, we had to contend with very high running costs. And then there is the problem of huge energy losses in the energy tanks storing the hydrogen.

"Still, to continue to work on the technology in the new hybrid energy station is commendable."

Not everyone in the Uckermark is thrilled by the new arrival. Many in this is sparsely populated area north of Berlin already complain about the 2,500 windmills as a blight on the landscape - a number set to double by 2020.

But local politicians see renewable energy as the best hope for the region, one of Germany's economic blackspots.

Brandenburg state premier Matthias Platzeck says the Enertrag plant will kickstart similar investment in the region in the coming years.

"The new hybrid technology will move Brandenburg forward as ‘energy country' and as a place for innovative solutions," he says.

"The Uckermark region has everything that energy producers and consumers could want."

The eastern state is home to several innovative projects, including a "clean coal" plant operated by energy company Vattenfall.

The Brandenburg state government is covering most of the €21 million cost of the Enertrag plant.

Enertrag operates 440 wind energy plants in Europe and had a turnover of €250 million in 2008.