FRANKFURT — Tesla Inc. CEO Elon Musk said on Tuesday that electricity consumption will double if the world’s vehicle fleets are electrified, increasing the need to expand nuclear, solar, geothermal and wind energy generating sources.

Increasing the availability of sustainable energy is a major challenge as cars move from combustion engines to battery-driven electric motors, a shift that will take two decades, Musk said in a talk hosted by Berlin-based publisher Axel Springer.

“It will take another 20 years for cars to be fully electric. It is like with phones, you cannot replace them all at once,” Musk said in a talk streamed on the Bild.de web site, adding that around 5 percent of vehicles are replaced every year.

Once EVs become the norm, electricity from intermittent generating energy sources such as wind and solar will need to be stored, probably through battery technology, he said.

“Together with large battery packs, both things need to be combined, wind power with battery packs and solar energy,” Musk said.

Tesla is embarking on plans to build its fourth gigafactory in Europe’s largest economy.

“The best wind turbines are made in Germany,” he said.

“I always have a good time when I am here. I like the engineering culture. People want to get things done.”

Tesla has recently acquired a license to trade electricity across western Europe, and the company has also been surveying customers in Germany about potentially using Tesla electricity in their cars.

Merger chatter

Meanwhile, Musk also said he was open to discussing a merger of Tesla with a rival.

Musk during the event in Germany was asked whether he would consider buying a rival carmaker given that Tesla’s market value of more than $500 billion would make it easy to launch a takeover bid.

“We are definitely not going to launch a hostile takeover. If somebody said it would be a good idea to merge with Tesla, we would have this conversation,” he said.