Gates spent a significant portion of his speech highlighting nuclear technology that would turn spent uranium -- the 99 percent of uranium rods that aren't burned in current nuclear power plants -- into electricity.

That technology could power the world indefinitely; spent uranium supplies in the U.S. alone could power the country for 100 years, he said.

A "traveling wave reactor" would burn uranium waste slowly, meaning a 60-year supply could be added to a reactor at once and then not touched for decades, he said.