These days, Microsoft's co-founder has more on his mind than software sales figures or even his charitable work -- namely he wants to help solve the world's energy problems. 

Philanthropist and former Microsoft CEO Bill Gates

FORTUNE -- At WIRED's Disruptive by Design Business Conference today, Bill Gates discussed the current state of energy and potential technology replacements for oil and coal.

Gates suggested there's much more potential for nuclear energy, despite the recent disaster with Japan's Fukushima reactor. As he sees it, nuclear has a "factor million" of energy creation compared with coal. And as he quipped, "coal plants kill, but they only kill a few at a time, which is highly preferred by politicians."

Really, the Fukushima reactor incident in his opinion is evident of just how little nuclear technology has improved over time and how ripe the technology is for innovation and investment.

"They had a design which worked on a submarine," he said.  "Then they went to generation 2 and got shut down due to Three Mile and coal in particular. There wasn't much design after that." Fukishima, Gates pointed out, was an older second-generation reactor based off 1960s design. Put side-by-side with future fourth-generation plants, the difference is night and day. (Note: Gates is an investor in TerraPower, a nuclear reactor design startup.) Fourth generation reactors have better ways of dealing with "afterheat," heat created by leftover radioactivity in a reactor, and could circumvent the problem completely. More