DW-TV: Professor Volker Quaschning, when in Germany the wind blows very strongly it can already overwhelm the electrical power grid. How come the big energy suppliers didn't invest in better grids a long time ago?

Volker Quaschning: So, the grids are constructed for the distribution of the energy from central power plants, such as coal power plants or nuclear power plants to the consumers, so in the future it will be totally different. So we have distributive renewable energy systems, solar systems, on each roof and we have to change the grid. But the problem is that renewable energy system they compete with the old power plants, with the nuclear and coal power plants and the owner of these power plants they are not interested in constructing new power lines.

So, if we turn off the nuclear power plants nowadays that's actually a good thing for the renewables?

Yes.

And you think that is possible, to turn them off?

Yes, of course. At the moment we see that we are going fast into the renewable energy technologies. So if you are looking to the 90s, we have had about three percent of renewable energy electricity in Germany. Last year we had 17 percent. And we'll see that it will be possible in 20 or 30 years to install 100 percent of renewable electricity generation in Germany.

You say it will be possible within a few years, 100 percent. How is that supposed to go?

We have to keep the fast growing rates of the renewable installations. So, for example, last year we have produced two percent of photovoltaic power in Germany, and more than seven percent of wind power. And we see that we can install about 20 percent photovoltaic power within the next 20 years. It's no problem; we only have to keep the installation rates we had in the last years.

You seem very confident. Already today we have 20 thousand wind turbines in Germany. Do you think people will accept even more wind turbines?

A lot of the wind turbines have been constructed in the 90s, so they are small wind turbines. We can change the wind turbines or we can repower them with bigger ones and this will increase the generation at the same place of electricity by wind power. We can also use some sites where we have no wind power, for example in Bavaria we have really no wind power plants. And we have to install wind power plants offshore in the North Sea. There are very big potentials that we can even supply the whole of Germany with wind power.

Remains the question of the money. Who's supposed to pay for that? In Germany we consumers already paid more than 10 billion euros just for the solar power last year. So who's going to come up for all the rest we need? How much is it going to cost?

The problem is that we see the cost of renewable energy in our energy bill. But we have additional costs, for example the cost for the nuclear risk, the cost for climate change, the cost for the subsidies for coal mining. All these costs are covered by other person but not in the energy bill or electricity bill. So if you include these costs into the total calculation the renewable electricity or energy supply is not even much more expensive than conventional power today.

Thanks a lot for the talk, Professor Volker Quaschning.

Interview: Ingolf Baur