Tovalu is running out of water. The floods make their normal drinking water reserves saline and unsafe to drink. Earlier Japan supplied a desalination plant. Normaly the technology is reverse osmosis or RO. But this technology is high energy and high pressure, making all parts relatively expensive. The energy requirement is also high. Why not use freeze desalination. Freeze desalination can be done using solar thermal energy, either to drive a thermal cooling cycle or to drive a heat engine that will vacuum cool the ocean water. This is a lower tech solution with less moving parts, no high pressure (although some vacuum if vacuum cooling is used) so easily maintained.
