Andrew Forrest, the Australian billionaire betting much of the fortune he made in iron-ore mining on green power, said doubters of hydrogen fuel-cell technology are “muppets.” That includes Elon Musk.

“Anyone, including Elon, including, you know, whoever you like, who says hydrogen hasn’t got a massive future are muppets,” Forrest said in an on-stage interview at the Bloomberg New Economy Gateway Africa forum in Marrakesh, Morocco, on Tuesday. “Battery and fuel cells are the way of the world in the future.”

Musk, the world’s richest person and founder of electric-carmaker Tesla Inc., has previously described hydrogen fuel-cell technology as “the most dumb thing I could possibly imagine for energy storage.”

While Musk uses lithium-battery technology in Tesla vehicles, Forrest is focusing on using green energy including solar to produce hydrogen, which is then stored and used to power fuel cells in the auto and other industries. The 61-year-old is the founder, chairman and biggest shareholder in Perth-based Fortescue Metals Group Ltd.

Tesla didn’t immediately respond to a request for comment sent by email.

--With assistance from Sarah Muller.