Batteries, fusion, and hydropower: Meet the 25 startups that Bill Gates is betting on to revolutionize the future of energy

· Microsoft cofounder and former CEO Bill Gates is the second richest person in the world, with a net worth over $110 billion. 
· He's invested a sizeable chunk of cash into clean-energy companies, largely through a billion-dollar fund he spearheads called Breakthrough Energy Ventures. 
· Gates funds a wide range of...