Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Uploaded on May 13, 2010
What is the Great Energy Challenge? See why energy is abundant around us, and how we have to find the best ways to harness it for use. ➡ Subscribe: http://bit.ly/NatGeoSubscribe
About National Geographic: National Geographic is the world's premium destination for science, exploration, and adventure. Through their world-class scientists, photographers, journalists, and filmmakers, Nat Geo gets you closer to the stories that matter and past the edge of what's possible.