German Energy Agency Chief: 'We'll Need Conventional Power Plants until 2050'.

German Energy Agency Chief: 'We'll Need Conventional Power Plants until 2050'.(Spiegel).Stephan Kohler, the head of the German Energy Agency, says the country must act smarter and more realistically in its transition to renewable energy. The "feel-good" subisides for locally produced wind and solar power have had unintended consequences, he says, and the envirnomental movement is often part of the problem.

SPIEGEL: Mr. Kohler, according to the government's plans, the last German nuclear power plant will go offline in 2022. What will the domestic power supply look like at that point?

Kohler: It will be interesting. It's easy to shut down a nuclear power plant, but that doesn't mean you have something to replace it with. We know today, for example, that we don't have enough reliable power plant capacity in southern Germany to be able to offset the loss of nuclear energy.

SPIEGEL: Solar and wind aren't enough?

Kohler: According to the generally accepted opinion, the transition to renewable energy sources means that we will give up nuclear power and rely on wind and solar instead. The reality is that we'll need conventional power plants until at least 2050, even if we do create massive renewable energy sources. Many people dispute this. They say that we could replace power plants operated with fossil fuels by adding more renewable energy sources. My response to them is: It won't work.

SPIEGEL: What's the problem?

Kohler: When a new wind farm is opened and we're told how many thousands of households it can supply with electricity, that number applies to only a quarter of our demand. In Germany, 75 percent of electricity goes to industry, for which a secure supply -- that is, at every second, and with constant voltage -- is indispensable. Neither solar nor wind power are suitable for that purpose today. Both fluctuate and provide either no secure supply or only a small fraction of a secure supply. Solar energy has a load factor of about 1,000 hours a year. But there are 8,670 hours in a year.Read the full interview here.