Is there a reason this wouldn't be subject to the same physics that requires a lot of energy to desalinate water by other means? Thermodynamics puts a limit on how efficiently you can reduce entropy like that.
I wouldn't say "a lot" in economic terms:
"The theoretical absolute minimum amount of energy required by natural osmosis to desalinate average seawater is approximately 1 kilowatt-hour per cubic meter (kwh/m3) of water produced, or 3.8 kilowatt-hours per thousand gallons (kwh/kgal)."
https://www.amtaorg.com/wp-content/uploads/7_MembraneDesalin...
