SIEMENS

There is nothing more powerful, the saying goes, than an idea whose time has come. Solar thermal technology - the generation of energy from the heat of the sun - has tried to get off the ground three times already. In 1912, the American Frank Shuman built a parabolic reflector system in Egypt that was expected to produce 55 kilowatts (kW) of power. "Twenty thousand square miles of collectors in the Sahara," he wrote, "could permanently supply the world with the 270 million horsepower it needs." But the world did not wait; it needed more and more horsepower and increasingly drew its power from oil and other fossil fuels. Solar thermal energy seemed to become a footnote in the history of power generation. It was only the huge increase in the price of oil in the 1970s that aroused new interest in the technology. Sixty years after Shuman’s first attempt, the Israeli company Luz developed new parabolic trough power plants. Nine plants from this period are still generating energy today in California’s Mojave Desert. But as the price of oil began to fall again, interest in solar thermal systems also waned. Power station projects were postponed or canceled, and Luz went bankrupt.

Now, almost 100 years after Shuman’s first project, the day finally seems to have come for solar thermal technology. Avi Brenmiller is one of the authors of this success. He remembers well the disappointments of the past decades: "In the 1980s, I was working on special coatings for the receiver tubes in which thermal oil is heated with concentrated solar energy. Our vision at the time was to master the whole chain - in other words, everything from the capture of solar energy and the steam cycle generation of electrical power. It was depressing to see how a promising technology suddenly lost support," he says.

But Brenmiller was persistent. In the course of a buyout, Luz became Solel, one of the leading suppliers of components for power generation systems using concentrated solar power (CSP) - and Brenmiller became CEO. In the first six months of 2009, Solel posted sales of almost $90 million. Then, in late 2009, Siemens purchased the company. With its staff of more than 500, Solel subsequently became Siemens Concentrated Solar Power Ltd. Brenmiller’s dream has come true.

Now, thanks to the acquisition, the key components, systems and solutions for solar thermal power stations covering the entire conversion chain can be supplied from a single source. Siemens Renewable Energy Division offers everything from parabolic mirrors to steam turbines. "This vertical integration is essential," says Brenmiller. "Concentrated solar power systems are highly complex; which means that the most important driver for maximizing efficiency is the perfect interaction of all components."

A Vision Becomes Reality. A power plant to consist mainly of Siemens components is now being built in Lebrija, Andalusia. The plant illustrates what a visionary project called Desertec might one day look like (see Pictures of the Future, Fall 2009, p. 19). The vision of the Desertec Industrial Initiative (DII) is ambitious. It calls for a network of solar thermal power plants and wind farms in the Mediterranean region, the Middle East, and North Africa to not only meet local demand, but to generate 15 percent of Europe’s electricity requirements. The industry consortium driving DII, which began its work in 2009, is currently developing economically viable strategies for the construction of a network of plants.

Construction work on the Lebrija 1 CSP plant in southern Spain began in 2008. The majority of its most important components are shipped from Israel and arrive at Cádiz harbor. The contents of the sea-freight containers destined for Lebrija, however, have to be treated as sensitively as if they were raw eggs. Up to 7,000 mirrors arrive each week. Almost 170,000 are needed to fit out what will soon be a 50-megawatt (MW) power plant. All in all, the mirrors account for approximately six percent of the plant’s total cost of almost €300 million. Receiver tubes - pipes that receive solar radiation from the mirrors and transfer it to a fluid - are another major expense.

The components are assembled on-site in Lebrija in a specially-built hall. "When we arrived, we found a cotton plantation at the site," says Siemens Concentrated Solar Power Vice President Moshe Shtamper, who is responsible for the construction of the thermal solar facility at Lebrija 1. His project team first had to remove the cotton and then have drains laid in the marshy delta of the Guadalquivir River. Now there are concrete pillars extending down as far as 40 meters into the ground, and the 6,048 parabolic troughs are mounted on top of these. Each trough consists of 28 individual mirrors that focus light onto the receivers. The parts are now being put together in the assembly hall by workers from the area some of whom used to earn their living by picking cotton. Using hydraulic hoisting cranes, they are combining individual mirrors to create parabolic troughs, which are then transported to the solar field by a tractor and trailer. There, cranes hoist the two-ton troughs into position.