Critical Mass: Is biomass the answer to our energy needs?

The burning of fossil fuels is currently the way we make most of our electricity, but the extraction of these materials can be costly and their supply is limited.  Plant cellulose is the most abundant biological material on Earth; is there a way we can harness this biomass material to fulfill our energy needs?  What plants are the most likely providers of energy?  How is the burning of this material less harmful than traditional fossil fuels?  Erica Baker gets some burning questions answered.