Excellent comment, Nate. Just like we all learned in school, from the sun's rays to plants to herbivores to carnivores, energy is lost every step of the way. Getting more from a cow than was put into feeding the cow would mean that energy was created out of nothing, and that's impossible. Even oil, which would not be around if not for the sun and is great because it has soaked up solar energy for millions of years (and is thus more dense than solar energy), is terribly inefficient, too. The best bet is to go directly to the source.

I've said before that 80% of American cropland is dedicated to feeding livestock, and there are many other reasons why growing livestock (at the very least the way we're doing it) is in no way beneficial to humanity (much less to the livestock, themselves).

I have the solution. We just need a gene therapy that will make us capable of photosynthesis. Then we can skip the intermediate stages and not have to eat at all. Throw in some cheetah genes so we can run real fast and we won't need cars.

Nah, we should just take Alice’s magic potion and become 1/10 th of our size. Then we’d only need 1/10th of the oil we consume today. Oops, we’d have to shrink the world as well to cut down transport ...oh, then we’d be shrinking the oil fields too, oh dear, back to the drawing board! Something will come up!

No, No. I think you have something there. Small, photosynthetic, and fast.

Once it goes transgenic in the wild we'll have ... Triffids!

That really would serve us right!