Manoj Bhargava may not be a household name, but his invention, the 5-Hour Energy drink, sure is. In fact, Bhargava's caffeinated concoction is so popular, it's made him one of the wealthiest men in the world. But Bhargava isn't just frittering away his newfound wealth. He's spending most of it — like 99 percent of it — making the world a better place.

Bhargava, the son of Indian immigrants who came to the United States with his family as a teen, is now worth an estimated $4 billion. And he's investing the bulk of it in a project he calls Billions In Change. The centerpiece of this initiative is his cutting-edge Stage 2 Innovations lab. At the lab, Bhargava has assembled a team of 30 or so engineers equipped with any tool or material they can think of. Their mandate? Solve the world's most pressing issues.

And the thing is, they're actually doing it.

Take the Free Electric bike project. Bhargava's team has come up with a way to generate enough electricity from pedaling a stationary bicycle to power a home for 24 hours. That could be a life changer for the more than 1 billion people still living without electricity. The Free Electric bike could also be used as a means to quickly get electricity to areas experiencing outages from a storm or other natural disaster.

The essence of the Free Bike project — and all of the Stage 2 Innovations initiatives — is that it's simple. It consists of a bike, a flywheel, and a small generator. If something breaks, it can be easily fixed by anyone who knows their way around a bike. And since it does not create any pollution or byproducts, the only side effect of using the bike is that they rider will get stronger and healthier.

Talk about a winning idea.

Bhargava's team has developed similar simple-yet-brilliant solutions for solving California's drought crisis (using a desalinator dubbed the "Rainmaker" that can turn seawater into drinking water,) the world's energy needs (with a custom-made graphene cable that can be inserted into the Earth's core to channel energy and heat to the surface,) and many other pressing global issues.

It's all part of Bhargava's pledge to give away most of his wealth. He recently signed on with the Giving Pledge, a campaign by Bill and Melinda Gates and Warren Buffet asking the world's wealthiest individuals to commit to give back to their community.

“The purpose of business, in the end, is to serve society,” he told Fortune. “I want to redistribute wealth in an intelligent way.”