[biblewonk]

Why is per acre important and not cost, renewability, or cleanness?

[discostu]

Cost is both a long term and short term issue, but in the long run the more space you need to generate power the higher the cost is going to be. Renewability is nice but isn't a real issue for any of our current sources of power. The problem with cleanness as a guide is that the two most clean methods we have right now for power (wind and sun) are grossly inefficient and you'd have to pretty much blanket the country with them to generate the power we need.