Tower of Power...aka Solar Chimney

Prototype Tower from Manzanares, Spain

Recently I stumbled upon a cool, or at least I think cool, renewable power source called the Solar Chimney, or Solar Tower. This system relies on an artificial temperature gradient at the base of the collector due to the installation of mirrors/glass at the base. Those collectors sit on top of tunnels, that just take in air from ground level, that is subsequently heated up. The heating of the air increases the localized pressure, think PV=nRT, since the volume is held 'constant' which in turn forces the air to flow up through the chimney.

By putting a turbine in between the heat source and the tower, you can capture the energy via the flowing air, and convert it to electricity.  Obviously the execution of a functional and economical power plant is a lot harder than my short description indicates, but that's why engineers get paid the big bucks. 

Source: www.geek.com

As expected, this system requires an area with ground heating, lots of sun and I'm willing to bet lower pressure at the chimney exhaust, ie not a pre-existing pressure gradient so the inversion effect wouldn't require a higher air pressure. The last item is a thought i have that is currently unsubstantiated by math, but a reason that one hasn't been put in LA, Salt Lake City or Vegas yet, even though they meet the other requirements.

This is another technology that wouldn't work well in densely populated areas as currently designed/envisioned due to the high cost of land(ie USD/acre or USD/sq ft in cities) and the need to have a strong understanding of the local winds. The inability to install in populated regions, coupled with the issues in transferring energy from areas where this technology could work(such as Arizona, New Mexico, Nevada) to the areas where the energy is needed on the coasts due to the grid issues highlighted in the last few posts.