Not hours per day. But if your climate has wet winters and dry summers you might choose to build a desalination plant that you only really need to run for three

Not hours per day. But if your climate has wet winters and dry summers you might choose to build a desalination plant that you only really need to run for three months per year. And then you have the plant sitting there for most of the year, able to help the power grid. So the example makes sense.