On Sun, 17 Nov 2013 08:57:45 -0700, Dan Marotta wrote:

You should see the solar towers southwest of Primm, NV (just inside CA),
USA. The top of the tower, surrounded by acres and acres of focused
mirrors appears to glow white hot. You can also see a dark cloud around
the tower. I wonder if that's plasma from super heated air or just the
remains of passing bugs and birds...

That's a very different beast which uses direct radiant solar heating to
heat a boiler. The French used a similar system as a solar furnace, which
NASA used to test Mercury program heat shields:

http://en.wikipedia.org/wiki/Solar_furnace


The type of solar chimney that the Australians were planning but never,
AFAIK, started to build and that the Spanish built as a 50kW experiment
and ran for eight years is almost exactly the inverse of the GE proposal.

Where GE would evaporate water at the top of a 2000 ft tower to cool the
air and cause a downflow to spin turbines as it exits the base of the
tower.

OTOH the Spanish/Australian approach surrounded the bottom of a similarly
high tower with a wide area of glass solar roof. This causes sunlight to
warm the air under the roof, which flows inwards and up the tower thanks
to the chimney effect and, in the process spins turbines mounted inside
the tower fairly close to its base. The designers have a choice of using
bare, blackened ground under the solar roof for maximum efficiency or of
accepting a bit less efficient generation, but making the solar roof
serve double duty by raising low-growing crops under the roof. The
Spanish experiment at Manzanares was a bit shorter - 195m, say 640ft.
Here's a reference to it:

http://www.sbp.de/en#sun/show/82-Sol...ant_Manzanares

There's a more general coverage of the idea and various projects, either
running or planned, he

https://en.wikipedia.org/wiki/Solar_updraft_tower


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
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