Bill Gates said at the Wall Street Journal’s Eco:nomics conference on Thursday night. In a 30-minute interview on the second night of the three day event, Gates discussed innovation in carbon capture, nuclear, biofuels, and clean power like solar and wind, and provided his thoughts on carbon taxes, politics and government funding.

 “Energy is the thing that allowed civilization over the last few hundred years to dramatically change everything,” Gates told the crowd gathered in the Bacara’s Ballroom.Gates himself has invested in a variety of energy-related startups, including nuclear company TerraPower, and battery company Liquid Metal Battery. In his talk he also said he is backing a startup doing gravity energy storage, which he referred to as “gravel on ski lifts.” He’s also a limited partner in Khosla Ventures, Vinod Khosla’s fund, and Gates jokingly referred to Khosla as “the pay master of crazy people — some of whom we’ll declare sane,” in the future. That’s what venture capital is all about, said Gates.

Gates said that it is particularly important to make sure that the “rewards are there,” for these crazy energy entrepreneurs, and “that is very unclear right now,” for grid-related generation technologies. You have to think why don’t we have more people doing things like that — what is holding these people back? said Gates.

Gates also had a word of encouragement for the energy entrepreneurs:

“I would encourage people who work in this area that the importance of this is right at the top.” The reason I spend time on it is because I think it is so critical to the environmental challenge and for helping the poorest. Cheap energy is like a vaccine.

This not going to be as easy as the IT revolution, said Gates, energy miracles are fundamental breakthroughs in science and engineering.