[pdonis]

> You can't be more than 100% energy efficient

Yes, you can, practically speaking. The amount of energy needed to produce a given amount of value to humans is not fixed; it can be decreased, and in principle can be made as small as we like given sufficient advances in technology. That means the amount of value to humans that can be produced with a fixed amount of energy can increase, in principle as much as we like. That's what the parent to your post was saying.

Obviously it will be a while before we have technology advanced to the point where, say, the amount of value currently being produced per year on Earth can be produced with one tenth or one hundredth or less of the energy it currently takes. But we also have a while before we hit any hard limits of the sort you are referring to.