DETROIT – Speaking in the Motor City on Tuesday, electric carmaker Tesla Motors’ co-founder and CEO Elon Musk again dismissed hydrogen fuel cell-powered cars as irrational, reported MLive.

“I just think they’re extremely silly,” he told reporters at Automotive News’ annual World Congress. His comments came on the same day Honda Motor Co. showed off its latest advancements in hydrogen fuel cell technology with its FCV concept at the 2015 North American International Auto Show. Toyota is also proudly displaying its production model, hydrogen fuel cell-powered Mirai at the show.

Musk argued that hydrogen acts as an energy storage unit, not a source of it, making it impractical for powering vehicles. He called drawing hydrogen from water “an extremely inefficient” process.

“If you’re going to pick an energy storage mechanism, hydrogen is just an extremely dumb one to pick,” Musk said.

He added, “The best-case hydrogen fuel cell case doesn’t win against the current-case batteries. So then obviously it doesn’t make sense. That will become apparent in the next few years. There’s no reason for us to have this debate. I’ve said my piece on this. It will be super obvious as time goes by.”

In addition to co-founding Tesla Motors, Musk, 43, helped launch and is currently the CEO of SpaceX, is chairman of SolarCity, and is a co-founder of PayPal.

He told reporters Tuesday that with Tesla he spends most of his time as an engineer and product architect.