The tanks look like they could hold propane, gasoline or any other form of conventional energy.

But the storage tanks in Prenzlau, some 70 miles north of Berlin, hold energy produced from wind. A hybrid power plant sponsored by four large companies is being tested there to see if the plant’s wind-hydrogen-biogas technology will work.

The system takes wind energy and turns it into hydrogen, which allows it to be stored. First electricity is produced in three wind turbines, which is then used to produce C02-free hydrogen. This so-called “green” hydrogen can be stored and mixed with biogas in a combined heat and power plant, to be used as needed in times of higher demand.

The resulting fuel can then be used for electricity or to power cars.

The technology is designed to solve a key problem in the renewables sector — how to store the energy that’s produced during a windy day for use when it’s dark and still.

The Prenzlau project can produce 120 cubic meters of hydrogen per hour. That can allow a hydrogen-powered car to travel 1,200 kilometers (745 miles).

Enertrag, a wind energy company with its base near Prenzlau, is leading the project. The company has 440 wind installations that produce 1.5 billion kWh annually — enough to support the yearly energy needs of 1.5 million people.

The other firms are TOTAL, the French oil giant, that has been testing and operating hydrogen fuel stations for automobiles for some 10 years in Germany. It is set to open another hydrogen fuel station at the new Berlin Airport when it opens this June.

Vattenfall AB, the Swedish-based energy conglomerate, and DB Energie GmbH, a subsidiary of the Deutsche Bahn AG, Germany’s federal railway, are also involved. The Prenzlau project’s construction started in 2009 and the plant went online last October. Some 21 million Euros ($35.7 million) were invested.

An additional alliance comprising of 14 participants from industry, science, academic and research and development areas was announced last December. Known as Performing Energy – Alliance for Wind Hydrogen, its goal is to support hydrogen energy efforts.

Vattenfall, a member of the Alliance that is financially supporting the Prenzlau project, is interested seeing just how far hydrogen technology can go, said its renewable energy spokesperson Lutz Wiese.

He said using hydrogen for electricity might not be so interesting in a large country like the United States, but it could work in Germany. He noted that a maximum volume of 5 percent hydrogen can be used in the energy network, but said it’s still a good use for the fuel.

Another interesting area is hydrogen power for cars, where technology has improved to allow for 400 km (248 miles) of travel on one tank, compared to roughly 150 km (93 miles) for an electric battery-powered car, Weise said. Vattenfall realizes that hydrogen and battery technologies are competing, but noted that German car maker Mercedes Benz AG is investing heavily in the hydrogen car.

“We’ll just have to see how it develops further,” he said, noting that being able to drive more than twice as much on one fill up is an attractive feature for potential buyers.

Not everyone is convinced. The Institute for Energy and Environmental Research in Heidelberg said in a report that hydrogen fuel cell systems are costly, with units ranging from 2500 to 5000 Euros ($4,250 to $ 8,500) per kW and a lifespan of 10 years, compared to 40 years for other large-scale storage technologies, which cost way less.

The IFEU does not believe that hydrogen will “become an important storage medium in the short or medium term.” Renewable energy’s share of the energy mix needs to be larger. If predictions hold out, hydrogen fuel may become an important element after 2030, it said.

“Hydrogen storage should not be given preference over battery systems. However, it should not be excluded either.”