Denmark is Aiming for 100% Renewable Energy by 2050Americans Consume Less Energy in 2012Asia Pacific nations will consume more than 50% of the worlds energy by 2035What exactly is the carbon cycle? Nathaniel Manning provides a basic look into the cyclical relationship of carbon, humans and the environment.Biofuels can provide energy without the reliance on environmentally harmful fossils fuels -- but scientists are still searching for a plentiful source. Craig A. Kohn demonstrates how cellulose, the naturally abundant tough walls of plant cells, might be the solution.Here's a list of TED Talks about the environment.