In an on-stage interview with TED organizer Chris Anderson, Elon Musk went into detail on his Tesla, SpaceX and SolarCity businesses, but his highest praise was reserved for the future of solar power. "I'm confident that solar will beat everything hands-down, including natural gas," Musk said, to applause. He added, "It must, actually. If it doesn't, we're in deep trouble."

Musk is the chairman of SolarCity, a solar leasing company which went public this December. The company promises to defray the initial investment cost of solar installation by offering 20-year leases, offset by lowered utility bills. "It amounts to a giant, distributed utility," Musk said. "This is the first time there's been competition against this [utility] monopoly." The end result, he predicted, would be that in 20 years time, solar will supply more power than any other source. "I'm confident it will beat natural gas."

In typically flashy fashion, Musk has put his money where his mouth is. Two years ago, he made a bet with "a friend who will remain nameless," that two decades later, solar would be the plurality source. He's got 18 years left to make good.