I don't understand "expending" energy in this case. Obviously a key part of the plan would be to use the unbelievable quantities of solar energy currently just

I don't understand "expending" energy in this case. Obviously a key part of the plan would be to use the unbelievable quantities of solar energy currently just going to waste. It doesn't even require high tech pv, just plain mirrors to make just plain heat for a large portion of the work. And pumping water is not just a cost, it's also a battery, a hugely valuable thing we don't have enough of yet, which would enable more of the grid to live on renewables. It's not all magic but it's not all impossible nor pointless either.