European Dream of Desert Energy Takes Shape
By Cordula Meyer
Can the Sahara Desert really meet Europe's voracious appetite for energy? The Desertec solar power project aims to do just that, but a host of obstacles remain. Overly optimistic expectations are now being scaled down as the project starts to take shape.
When the sun rises and it's still hazy over Andalusia, the future is particularly visible. That's when beams of light as thick as tree trunks and as sharp as lasers slice through the haze. They come together just below the tops of two towers, the taller of which rises 162 meters (531 feet) into the sky, taller than Cologne Cathedral. These light beams are not being emitted by some UFO, but are in fact the core of the most advanced solar power plant in the world.
The towers are surrounded by close to 2,000 mirrors that face the sun. Each mirror has a surface area of about 120 square meters (1,290 square feet) and, like flowers, they follow the light, to the sound of a rattling motor that orients them toward receivers up in the towers. The bundled solar energy, which reaches a temperature of 250 degrees Celsius (482 degrees Fahrenheit), strikes steel pipes through which water is conducted. The water vaporizes and drives a turbine. The facility, known as PS20, is the world's largest solar power tower and generates enough electricity for 10,000 households.
There is not a cloud in the sky on this spring morning, 20 kilometers (12.5 miles) west of Seville. "It's easy today," Enrique Sales Rodriguez says with satisfaction, as the turbine roars and the tower runs at full capacity. Rodriguez, an engineer, monitors the technology from a control room at the base of the tower. He reacts quickly whenever large clouds appear in the sky, making adjustments to the system to extract as much energy as possible from the rays of the sun. Everything is designed to increase the harvest of light. Trucks equipped with large blue cleaning brushes are constantly roaming through the rows of mirrors. "We clean 24 hours a day," says Rodriguez. more
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