Researchers prepare to test solar dish

By LEAH KRAUSS, UPI Correspondent   |   March 13, 2006 at 8:16 AM
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SEDE BOKER, Israel, March 7 (UPI) -- At the end of a dusty road in the middle of the Negev Desert sits the world's largest solar collection dish and researchers are getting ready to take it for a test drive.

Next week's tests at Israel's National Solar Energy Center in Sede Boker will be conducted with European partners and funding. The experiments will measure how much power the 400 square meter dish -- roughly the area covered by a basketball court -- could really create, the center's director, professor David Faiman, told United Press International.

The dish is lined with 216 mirrors, but not more than a quarter will be uncovered to sunlight for the experiments. The mirrors concentrate the light onto a small square of concentrator photovoltaic cells, which convert the light into electricity.

"First we'll hit (the concentrator photovoltaic cells) with the equivalent of 20 suns, and measure how much power is produced. Then we'll hit it with 40, and so on, up to the equivalent of 1,000 suns," Faiman said.

"The (concentrator photovoltaic cell) panel, which, of course, is much too small for the dish, is 10 centimeters by 10 centimeters," Faiman said of the panel that will be used for the experiments.

"To take full advantage of the power our dish could offer, the panel would need to be something like 65 centimeters by 65 centimeters," he added.

Most solar panels use regular photovoltaic cells, which are much bigger and less efficient. They serve two functions: to collect the sunlight and to convert it. The regular photovoltaics are "a nice and simple way to convert the electricity, but ... too expensive to collect (the sunlight) this way," Faiman said.

Producing the energy equivalent of 200 million barrels of oil per day -- the world's approximate consumption rate in 2004 -- would require covering 750,000 square kilometers of desert with photovoltaic cells. At about $500 per square meter, such a quantity of photovoltaic cells would run a $325 trillion price tag, Faiman estimated.

So Faiman and the center's researchers have split the functions. The mirrors, an inexpensive material, collect the sunlight and concentrate it, and the small, high-capacity concentrator photovoltaic cells do the converting.

Remember frying ants using a magnifying glass to focus the sunlight into a dot onto their backs? It's the same principle, and as any kid will attest, it's much more efficient than waiting for the ant to spontaneously combust under a normal amount of sunlight.

This efficiency means the same 200 million barrels of oil equivalent could be produced with only 750 square kilometers of solar paneling - 1,000 times less than the normal panels and at a significantly lower cost, Faiman said. Producing enough energy to meet the world's demands would still require 750,000 square kilometers of mirrors to collect the sunlight and concentrate it on the concentrator photovoltaic cells, but glass for the mirrors is much less expensive.

In fact, according to a study Faiman published last year, mass producing dish systems like the Sede Boker model would cost less than $1,000 per kilowatt to produce -- the cost of a typical, fossil-fuel burning plant.

The Israeli government, which partially funds the Sede Boker center, has set a goal to convert 2 percent of the country's energy use to solar by 2007, and 10 percent by 2017, Ministry of National Infrastructures spokesman Elad Sasi told UPI.

In general, the ministry is "fairly encouraging" of attempts to go solar, Sasi said.

However, the site is formally part of the Ben Gurion University of the Negev. This may explain the disconnect between the government's goals and the no-frills look of the center's facilities, which comprise a few small free-standing offices clustered around the dish. The staff is also bare bones: three scientists, including Faiman, a technical staff of three, and an administrator.

Another force in Israeli solar energy is the private company Solel, which already operates solar-thermal power plants in the U.S. Southwest and has turned its sights on building Israel's first solar-thermal plant.

Solar-thermal plants, unlike those that use the concentrator photovoltaic cells, use sunlight to create steam that powers traditional turbines.

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