April 30, 2008
HARNESSING THE SAHARAN SUN
Is Desert Solar Power the Solution to Europe's Energy Crisis?
A tiny fraction of the sun's energy that shines upon the deserts of North Africa and the Middle East could meet all of Europe's electricity demands. The technology to harness the energy already exists. So why is hardly anyone investing in it?
The oil of the 21st century is not buried deep within the earth. Instead, it falls on its surface -- as sunshine.
"The sun is the hidden asset of North Africa and the Middle East," says Gerhard Knies, a spokesman for the Trans-Mediterranean Renewable Energy Cooperation (TREC), a network of scientists and politicians from various countries who have taken it upon themselves to solve Europe's energy problem.
Their vision, which they call Desertec, is to turn desert sun into electricity, thereby harnessing inexhaustible, clean and affordable energy.
"We don't have an energy problem," says Hans Müller-Steinhagen, of the German Aerospace Center (DLR). "We have an energy conversion and distribution problem."
Müller-Steinhagen has been commissioned by Germany's Environment Ministry to check the feasibility of Desertec in several studies. His conclusion is that Desertec is a real possibility.
In his studies, he has scrutinized the energy situation in Europe, North Africa and the Middle East from the point of view of the post-oil era. Out of all the alternative energy sources, one stands head and shoulders above the rest: "No energy source even comes close to achieving the same massive energy density as sunshine," Müller-Steinhagen says.
And no other energy source is available over such a large area. Every year, 630,000 terawatt hours in the form of solar energy falls unused on the deserts of the so-called MENA states of the Middle East and North Africa.
In contrast, Europe consumes just 4,000 terawatt hours of energy a year -- a mere 0.6 percent of the unused solar energy falling in the desert.
Powering Europe from the Desert
Europe needs a lot of electricity, but gets little sun. The MENA countries, on the other hand, get a lot of sun, but consume little electricity. So, the solution is simple: The south produces electricity for the north. But how would the enormous energy transfer work? And how do you turn desert sun into electricity?
It's actually relatively easy. Desertec is low-tech -- no expensive nuclear fusion reactors, no CO2-emitting coal power plants, no ultra-thin solar cells. The principle behind it is familiar to every child who has ever burnt a hole in a sheet of paper with a magnifying glass. Curved mirrors known as "parabolic trough collectors" collect sunlight. The energy is used to heat water, generating steam which then drives turbines and generates electricity. That, in a nutshell, is how a solar thermal power plant works.
Energy can be harnessed even at night: Excess heat produced during the day can be stored for several hours in tanks of molten salt. This way the turbines can produce electricity even when the sun is not shining.
Should the Sahara, therefore, be completely covered with mirrors? No, says Müller-Steinhagen, producing a picture by way of an answer. It shows a huge desert in which are drawn three red squares. One square, roughly the size of Austria, is labelled "world." "If this area was covered in parabolic trough power plants, enough energy would be produced to satisfy world demand," he says.
A second square, just a fourth of the size of the first one, is labelled "EU 25," in a reference to the 25 member states the European Union had before Bulgaria and Romania joined in 2007. This area could produce enough solar energy to free Europe from dependence on oil, gas and coal. The third area is labelled "D," for Germany. It is merely a small dot.
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http://www.spiegel.de/international/world/0,1518,550544,00.html
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