A bunch of people informed me that the solar enery harvesting technique I came up with is an example of what's called 'solar thermal energy'. Zaitcev has a good analysis of my exact proposal. (The upshot is, it's a lot easier to get the water hot enough to boil it then use a plain old rankine engine. Parabolic dish ones tend to use stirling engines.)
The biggest current solar thermal energy plant is a solar tower. A cheaper design (when done at sufficient scale) is a solar chimney Solar chimneys are a monument to inefficiency but in the desert we have more solar energy than we know what to do with, so the real issue is cost rather than efficiency. The robustness and simplicity of solar chimneys is certainly appealing. After the cost of construction is amortized out after thirty years or so, it produces energy essentilly for free and with hardly any maintenance.
My next question is, could lightning thermal energy be viable?
In other engineering news, there's a new desalinization trick.