The Seawater (Solar) Greenhouse is an interesting relatively low-tech idea for inexpensive desalination, turning sea water into fresh water. The Greenhouse concentrates energy directly from the Sun, to evaporate salt water, collecting the fresh water as condensation. It doesnt need any other energy source directly for desalination, just a much smaller amount to run the pumps that move the seawater to and around the Greenhouse. This can be powered by Solar Panels, but apart from the pumps/panels, the rest of the Greenhouse could be built from materials similar to an ordinary Greenhouse, at a capital/running cost far below that of a traditional desalination plant.
There is already a working 20 hectare system in Port Augusta, South Australia, where the process is used to generate water for commercial salad crops. It is an idea that has been around since the 1990s, but yet to be very widely exploited, so there is much that might be done to improve the efficiency of the existing systems, and reduce costs. The ideal system might be a kit of parts that can be assembled in any hot arid area that is near the coast, and generate cheap fresh water.
Maybe it can supply some areas of recent wildfire damaged forest, to help water/protect new trees during summer droughts.
Given current climate concerns, this might be an idea whose time has come.
https://en.wikipedia.org/wiki/Seawater_greenhouse
A.M.