Earlier quoted context omitted.
> Same with the water consumed by those crops. Every drop of water on Earth has been "consumed" many, many times over. It doesn't just get used once and then disappear. There may be localized shortages of water (e.g., in California), but that doesn't mean that the Earth's water overall gets "used up", in any meaningful sense.
That ain't what I'm saying. Every inch of land on Earth has been "reused" many times over, too. That doesn't change the fact that there's a finite amount of it, and the possession of any quantity of it is at the expense of everyone else needing it. Same goes for water; yes, the water itself doesn't magically disappear, but of the 1,386,000,000 cubic kilometers of water on this planet, if you're storing a trillion of…
All the water tanks in the world don't add up to a trillion km³. Not by many orders of magnitude.
> the resulting labor and energy costs of converting the latter back into the former
The sun does that for free, and has done for billions of years.