Louvered “window shades”
adjust the burn rate in a high-temperature research oven.
Solar Platform of Almería, in
Spain, uses the facility to test
high-temperature materials
used by, among many others,
the European Space Agency.
desalination plant demonstrating how thirsty
southern Spain extracts fresh water from its
salt oceans. any amount of heat above 212°F
(100°C) boils water, so capturing an entire field
of concentrated heat is the ideal mechanism to
desalinate water. Models designed at PSa show
that the process is straightforward. Sea water
bathes an array of tubes filled with hot air. Concentrated sunlight boils off the water. The vapor
condenses and is collected as distilled water,
leaving the salt behind. after a time, the salt is
blown off the tubes with a jet of compressed air,
and is packaged for use by industry. The result: a
rainfall of water in desert climates and raw material for manufacturing, all powered by the sun.
Researching High-Temperature
Materials
The next demonstration was a testing lab for
high-temperature materials. It’s an industrial-grade solar oven about the size of two garages
stacked vertically. Heliostats outside the oven
target an enormous parabolic mirror, which further concentrates the rays onto a single, white-hot spot. The European Space agency uses
this rig to test materials for rocket motors and
re-entry vehicles because the focal point recre-
38 May 2010 SOLAR TODAY solartoday.org
•;The;third;form;of;concentrating;solar;ther-mal power is the tower system. This places a
receiving tower, about the size of a tall silo,
in front of a fan-shaped array of heliostats. These
are tracking mirrors that focus the sun onto
a small tank at the top of the tower. Traditionally, the receiver tank contained oil or a salt
solution to transfer the heat to the steam turbines. Recent projects use simple air, heated
to about 1,400°C ( 2,552°F). an 11-MW test
project is functioning in Seville, Spain, with a
new 150-MW site under construction.
Models of all three systems are being redesigned and improved within the compound at
the Solar Platform. Researchers continue to perfect each step of the process: developing new
transfer media, improving the software to control hundreds of tracking mirrors and increasing
the lifespan and efficiency of the components.
after showing us an introductory video and
a quick turn through the display of models at
headquarters, Dahlia led us out to an electric bus
(recharged from solar sources) for our tour.
Purifying Water, with the Sun
Solar thermal technology is not just about
electricity anymore. Researchers at PSa have
expanded into several other uses that will be as
valuable to us as sustainable energy. Clean water,
for example.
Residues of pesticides and other contaminants from farming and manufacturing include
carcinogens. Each rainfall percolates the chemicals from farm fields and factory grounds into
our fresh water aquifers. an ultraviolet (UV)
trough system developed at PSa reflects UV
rays onto tubes of contaminated water. add a
pinch of titanium dioxide to initiate the reaction,
and in only a few minutes you have clean water
again, with a slight emission of carbon dioxide
and biodegradable acid. It even works on cloudy
days, because UV waves penetrate the clouds. In
the demonstration I watched, the pesticide-filled
water turned blue for a few minutes as the cleansing reaction took place, then cleared, ready for
use again as contaminant-free water.
Dahlia glided us silently to our next stop: a
ates the temperatures of rocket re-entry into the
Earth’s atmosphere, or 3,000°C ( 5,400°F). The
Solar Platform group demonstrates this by melt-
ing a four-inch hole, in what looks like grandma’s
old iron fry pan, in under three minutes. That’s
a half inch of iron, melting faster than my ice
cream bar in the desert sun. a large set of old-
fashioned blinds, very much like the kind you
Dahlia, the author’s chauffeur for the solar tour,
arrived in a silent yellow electric bus.
