"is neither cheap nor all that clean."

In terms of greenhouse gas emmissions, it's very clean. That's the whole point of bothering with green energy.

"If you are in a location with plenty of sunlight and wind, I don't see how this could possibly by less expensive than some kind of integrated wind turbine/solar PV/solar thermal linked-to-storage grid of the same capacity."

Unsurprising - things that exist are generally more expensive than things that don't. I'm not sure how you can even assess the cost of storing the power from those sources to compare them.

Until a realistic method of storing that energy is created (if it ever is), nuclear as well as waste-incineration and hydroelectric are superior by virtue of being viable.