Robin van Spaandonk wrote:
By going to 500 Suns, they reduce the size of the solar cell
required, and hence also the cost. Of course the temperature would
be prohibitive without cooling, so they may also be extracting
useful energy from the cooling fluid.
If they have to do that it is much too complicated! In my opinion,
the only real advantage to PV is that it has no moving parts: no
fluid, no tracking mirrors. If you have to introduce fluid and
cooling methods you might as well go to solar thermal.
I think they would have to do active cooling with 500 suns (which is
how it is expressed in various articles I have seen today). That must
make it awfully hot! Maybe there is a typo or misunderstanding here.
20 seems more like it. My impression is that with 500 suns you would
burn or vaporize any normal chip, if 80 suns brings the temp up to
400 deg C in the SEGS array. (SEGS are the power plants built by Luz
in California -- still the world's largest. SEGS Harper Lake is 160
MW! Operational since 1989. I can't imaging doing that with wind or PV.
http://www.solel.com/products/pgeneration/ls2/harperlake/
I hate to use Wikipedia, but this photo shows damaged mirrors, which
indicate the limits of the technology (the lifetime of the installation):
http://en.wikipedia.org/wiki/File:Solarplant-050406-05.jpg
PV installations have a short lifetime too. Years ago I read that PV
output declines rapidly after ~8 years and after ~16 years they are
useless. I expect they are better now, but still, leaving something
in bright sunlight and outdoor weather is not ideal. The surface gets
dirty and the materials separate. Years ago the overall output from
the PV chip over the life of the chip was barely enough to cover the
energy cost of manufacturing the thing. Kind of like ethanol.
Wind turbines last a long time, like hydroelectric equipment. (For
the same reason: temperatures and power density is moderate, and the
installation is self-cooling.) The towers, which are the most
expensive component, will probably last 100 years or more, with
proper maintenance.
Without maintenance things fall apart in no time. I have noticed many
buildings in Atlanta falling apart lately. A friend who works in
building maintenance and construction told me that commercial
landlords are broke and not doing basic maintenance such are removing
plants that grow on buildings. There is a huge brand new shopping
center complex next to the abandoned GM plant at Peachtree and 285,
built for the H-Mart Korean grocery chain (which is fabulous, by the
way). It was supposed to open this January. The complex has two
tenants and ~50 empty stores. It is rusting and falling to pieces. It
reminds me of the photos from the Great Depression and from England
between 1939 and 1952, when no building was painted and no fences
repaired. The Atlanta newspapers say: "What is the difference between
Detroit and Atlanta? In Atlanta, the abandoned buildings are new."
- Jed
