You know the wind is changing for renewables — so to speak — when the head of Europe’s biggest power producer becomes an advocate — and then even decides to reduce his own personal reliance on fossil fuels by powering and heating his new house with photovoltaic and geothermal energies.

Wulf Bernotat, the chief executive of E.ON, admits he became rather belatedly an advocate for renewable energy, even if his company still gets the lion’s share of its 70 billion euros in annual turnover in 30 countries from burning fossil fuels. The reasons for the change of heart? It’s one answer to climate change, it’s the way the political winds were blowing, and there are profits to be made.

“We had a certain reservation about renewables until about a year ago and then we abandoned those reservations because we recognised that renewables are desired politically,” Bernotat said after a recent presentation to a group of journalists in Berlin. “That’s why it’s the right decision for us to get more actively involved.”

Bernotat also predicted that renewables will replace fossil fuels as the world’s most important energy source by 2050 and possibly even “completely displace fossil fuels by the end of this century.” It was an amazing forecast from a company so closely linked to coal-burning power plants — like a butcher saying everyone would become vegetarian by the end of the century.

Less known is Bernotat’s own personal commitment to renewables — he did not make a big deal about it but had mentioned once in passing in a German TV talk show that he planned to use geothermal power and photovoltaic on his new house. So when I asked him about it, his face lit up like a Christmas tree. He said using renewables made economic sense in the long run despite the heavy initial investment — he had to drill six holes 100 metres deep in his back yard to tap geothermal power for hot water and heating (I wish my wife would let me do that). He said he did it for his daughter, who would be able to reap the longer term return on the investment in renewables — although he too is reaping handsome returns now too. “It’s easier when you build a new house,” he said. “Then it’s easier to reduce CO2. But if you’ve got a house already and the gas-burning furnace is only five or 10 years old, it’s a more difficult matter. Do you really want to replace a furnace like that now?”

When I mentioned to him that a local E.ON subsidiary was buying my 6,000 kilowatts of photovoltaic power off my roof for nearly 3,000 euros each year — and thanked him half in jest for the prompt monthly payments — Bernotat just laughed and said: “Don’t thank me. It’s the other energy users (who pay higher monthly electric bills to subsidise photovoltaic providers like me) who are paying you for that. So thank them!”