In a world where most grid electricity energy is from solar (with wind, hydro etc only supplying small amounts), you would need to balance out the load somehow. One idea I've had is to use "reverse peakers". Our current grid uses power plants that are relatively cheap by capacity (watts) but expensive per watt-hour to run, like diesel, to briefly balance load spikes.
In this world, electricity demand that exceeds current supply is brought from other continents by superconductive power lines. However, this only has about 10% of peak generation capacity, so electrically intensive industries are done during the day. Most heat related energy needs, especially residential space heating is still done with natural gas.
However to manage local excesses of energy, they would like time their use desalination plants to "reverse peak", to soak up excess energy.
What would the energy density of this practice be like? How would it compare to normal hydro electric ponds energy density, assuming hydro storage has normal loss inefficiencies but desalination does not. This is because it's not being used to generate more electricity, it's an "offset" equal to the amount of energy it took to create, that would have been drawn from the electrical grid. Update: As used here, energy density is the total energy(watt-hours or equivalent) per unit of volume (Assume non hand-wavuim desalination for this portion, i.e. currently realistic).
Bonus: If this society uses solar powered desalination to provide the bulk of its agricultural water, given hand-wavium solar panels that are ten times cheaper, but not more efficient, and ×10 energy inefficiency nano-prefix desalination, would it feel more like a utopia or a dystopia? (Yay! Bread-basket Sahara or Boo! Corn is $20 a pound)
- Why do we desalinate? — World population of 30 Billion+, can survive without it but more comfortable with it!
- Why do we mostly rely on solar? — Because fusion sucks, nuclear is "scary", fossil fuels are dirty and the other power sources I mentioned aren't available everywhere.
- Why isn't there any grid level storage? — I am not aware of any good grid level storage solutions. That link to the superconductive based storage may change my mind, however.
- How do people deal with cloudy days? — Continental grid can match local variances easily. Capacity is designed to meet needs in subpar conditions anyway.
- Do we have any major issues (e.g. food shortage?) Lets add in the 30+ billion population for this too. Can we meet our food needs, presumably by lifestyle change or irrigating more farmland than before? How about luxuries like beef and alcohol?