Europe can meet 100 percent of its power supply from renewable sources by 2050 if countries work together and massively invest in grids and storage, experts and politicians say.

"This is not utopia but a vision that can be realized," Michaele Schreyer, a former European Commission member, said Tuesday at an energy conference in Berlin organized by the German Green Party-affiliated Heinrich Boell Foundation.

Schreyer was part of a panel discussing how realistic it is for Europe to one day meet its entire power demand from renewables.

The panelists said such a goal was economically and technically possible.

Christian Hey, an energy expert with the German Advisory Council on the Environment, said Europe and North Africa together have an exploitable renewable power potential of 140,000 terawatt hours -- more than 20 times the maximum possible demand.

The European Union has set a target of 20 percent renewables by 2020. The European Commission this month published forecasts that the 27-member club was on its to way to slightly exceed that target.

That means change is already gripping the sector, said Claude Turmes, a European Parliament member for the Green Party and one of Europe's most active energy politicians.

More than 60 percent of global investments into the energy sector in 2009 went into renewables, he said, adding that nations installed 80,000 megawatts worth of wind and solar power capacity from 2000 until the end of last year. During the same period, 31,000 MW of oil, gas and nuclear capacity were taken off the grid, he added.

"So we are already on our way," he said.

The problem is that Europe isn't united in that way.

France, for example banks on nuclear power to reduce its carbon dioxide emissions, while Germany still has a nuclear phase-out agreement by 2021 in place. Countries in Central and Eastern Europe want to build coal-fired power stations to produce cheap power and aren't ready to cut their CO2 emissions as drastically as others.

Moreover, national governments are unwilling to hand Brussels competencies that would affect their domestic energy mix. The fruits of the disunity have in the past been bilateral deals with energy giants Russia, China and India that sometimes directly counteract each other.

"The much-heralded European energy solidarity exists only on paper," said Ralf Fuecks, the head of the Heinrich Boell Foundation.

Yet exactly such is needed to achieve an affordable and stable energy system based on renewables, experts say. The green energy sources are fluctuating and that's why it's key to have a smart grid and lots of storage possibilities.

If a country like Germany, which has a large wind power but limited storage potential, tries to go it alone, it can end up with a functioning renewable energy system but a very costly one, said Hey, the energy expert.

"Cooperating with just Scandinavia would already make such a system much cheaper," Hey said. "The bigger the cooperation, the cheaper the system."

Linking solar thermal power plants in Spain with geothermal energy in Italy, offshore wind farms in Britain and hydropower storage systems in Scandinavia would produce a power system that is both stable and affordable, he added.

But to realize that vision, Europe needs "strong political will from all member states," said Arne Mogren, a special adviser to Lars Josefsson, the chief executive officer of state-owned Swedish utility Vattenfall, and "massive investments in a new electricity grid."

Vattenfall has just announced its decision to sell its German grid to a group of Belgium and Australian investors. It seems unavoidable that Brussels comes up with cash or at least incentives to modernize the European grid.

Mogren added he believes a 60-80 percent renewable share is possible only if "we are very successful in this."

Then, the vision of a power system banking on a significant share of renewables could become a reality.

"In the beginning of the European Union stood the unity for coal and steel," Schreyer said. "Why not make a fresh start with green energy sources. The plan to call for a European Union of Renewables could spark a new enthusiasm for Europe."