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Parabolic gutter collectors have been around for more than a hundred years. Swedish-American John Ericsson used one to drive a hot air engine way back in 1880. Further German, British and American patents followed.
Demonstration plant with 500 KW
The first demonstration plant with parabolic gutter collectors and electrical capacity of 500 Kilowatt went into
operation at the Spanish Plataforma Solar de Almeria in 1981. This was followed by other power plants in Europe and the United States. By the end of the 1990s, however, the technology had not been developed much further.
New collectors ...
That is, until a European group began to prepare for the construction of large solar power plants as a response to the growing demand for energy worldwide and in view of the obligations set down by the Kyoto accord. With support of the EU, Stuttgart-based engineering firm Schlaich Bergermann and Partners developed a new, forward-looking collector structure for parabolic gutter power plants. The planner seamlessly used Allplan for the entire steel-welded construction of the facility: from design and the creation of drawings to workshop planning with all components of the steel structure in 2D or 3D. As a result, more than 105 A0 plans were created and exchanged with other design professionals and the client in PDF file format, among others.
...pass the test
In 2000, the first prototype was set up at Plataforma Solar de Almeria. Good results inspired the draft design
of a commercial 50-megawatt power plant in Spain. To minimize the risks involved in moving from a small prototype to a large power plant and to test the new collector technology in practice, a further demonstration
plant was first built in the United States. The complete, 100 ton steel construction was produced in Turkey,
shipped in containers, and assembled in California. To ensure optimum optical performance of the collectors,
the individual components were first manufactured with the usual precision.
Spain paves the way ...
The final collector geometry with a tolerance of just a few millimeters was achieved with the use of precision
assembly devices. The results were impressive: material consumption was reduced, and energy yield increased by 10 percent thanks to the higher rigidity of the construction and improved adjustment. In 2004, the Spanish government voted in a law on the supply of energy for solar thermal power. As a result, Spain has paved the way for the construction of 50 to 100 MW solar thermal power plants in Europe.
... for large solar power stations
In the solar power plant, concentrating collectors track the sun uniaxially. Their parabolically curved mirrored surface reflects the light to a vacuum-insulated absorber tube that runs along the caustic curve of the mirror.
Synthetic oil, heated by sunlight to around 300 °C solar and provided via a heat store (molten salt), is pumped
through the tube. The concentrated solar radiation heats this to about 400°C. The successive switching of
individual collector elements creates loops that are over one hundred meters long. The heat transfer medium
of many of the loops is fed to a steam generator which is connected to a conventional steam turbine with generator. The collector field is dimensioned so that it not only provides sufficient thermal energy during the day to drive the turbines, but also loads the heat store sufficiently that the turbines can continue for another six hours at full power after the sun goes down.
510,000 square meters of mirror
In 2006, Spanish construction company ACS Cobra and project developer Solar Millennium began to build the first of three planned 50 MW facilities. It is located in a high valley between Almeria and Granada, close to the small town of Aldeire. A total of 7,488 collector elements, each 12 meters long and approx. 5.8 meters wide, are installed over an area of 1.3 by 1.5 kilometers. This produced a collector field with a mirror surface area of 510,000 m2. The solar radiation at the location is about 2,100 to 2,200 kWh/m2. Thus, annual solar power production will be about 179 gigawatt hours per power plant. Work on the second power plant began in the spring of 2007, and the facility should start operation in two years.
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