David M. Rubenstein may be worth billions today, but it wasn’t always that way. The self-made billionaire worked hard to get where he is, and even through all that work he hasn’t forgotten how important it is to give back to the community and world at large.

A member of the lucrative Giving Pledge, the Carlyle Group co-founder has promised to give away at least half of his wealth during his lifetime or upon death. He’s already begun following through on that promise.

One thing David M. Rubenstein certainly has a passion for is leading the U.S.’s energy revolution. He has donated millions to support students studying energy policy and the environment.

To find out more about how this business guru is changing the world for the greener, check out his complete profile.