The first law of thermodynamics (conservation) holds that energy cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another. Simply put, we cannot get energy from nothing.
Think about what that means for our hopes (and dreams) of a carbonless future for energy. Unless the first law of thermodynamics is disproved, we will always have to transform some form of matter or energy to get energy. If not carbon, then something else. Neutrons for nuclear plants. Food for biofuels. Land for windfarms. Silicon or some other material for solar panels.
Which leads to that other basic law. There is no free lunch.