[ulkhf]

Capital cost of these plants is significant, which is why most of them run 24 hours per day. If you only run them 8 hours per day, you triple the capital cost.

[nine_k]

How do you power such plants? Good thing if you're an oil-rich country that can just readily burn what flows from the wells anyway (say, UAE). A bit harder if you don't have anything like that (say, Namibia or West Sahara).

[more_corn]

There are small scale desalination designs like the slingshot.