I am now a vegetarian. Woo!

[Aerith's Knight]

Perhaps the technology is near that'll allow us to synthesise a nutritionally perfect food, using no animal or plant products but providing a completely balanced diet. That'd be cool, and depending on the production costs and energy demands, it could be a great move in environmental terms too. But unless or until such a food is developed, the continued harvesting of animals and plants remains a necessity.

And where would that energy come from?

Im guessing that somewhere in the process things would be burned, or made by burning stuff. you could use nuclear energy of course, but i doubt if that would be more benificial to the enviroment.