40 Under 40: Ones to Watch

This is no runners-up list—we're watching these 12 high-flying individuals closely, and you ought to be, too. They come from the worlds of finance, tech, energy, politics, and even sports. Meet our 2013 Ones to Watch.

Danielle Fong

40u40 ones to watch danielle fong
  • Age: 25
  • Title: Cofounder and chief scientist
  • Company: LightSail Energy

If Danielle Fong were a fictional character, she wouldn't be plausible. She lives in a refurbished fire station, started college at age 12, and has a plan to boost the viability of green energy that has attracted attention from some of the world's greatest thinkers. LightSail's technology represents a new take on energy storage that it says will be cheaper and more efficient -- retaining some 70% of a stored charge, much higher than what's possible with existing equipment. Energy storage is a serious hurdle for power sources such as wind and solar, which can only be harvested for part of the day. If it works, LightSail's solution could "make renewable energy practical and mainstream for the first time," says Vinod Khosla, an early investor in LightSail. He's not the only luminary backing the company. Bill Gates and Peter Thiel are also on board, helping boost the startup's funding to more than $50 million. Fong, who drives a Tesla and uses Google Glass, lives in the firehouse that was her company's original headquarters and says she'd like to throw her 40th birthday party "in space." Far-fetched? Maybe not. -Anne VanderMey

  @FortuneMagazine - Last updated September 19 2013 07:26 AM ET
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40 Under 40

Our 2013 edition of the list features young hotshots who are rocking businesses as diverse as air travel, natural gas, and genetic coding, as well as—if you can believe it— government.

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