Solar Energy

Gigantic and powerful: The mirrors of the solar collectors at each of the AndaSol power plants take up a surface area of over 510,000 square meters. Photo: SCHOTT/J. Meyer
Martin Frey

Power Plants of a New Dimension

The first of three AndaSol power plants has now gone live in the south of Spain. SCHOTT provided the receivers.

AndaSol 1, the first commercially operated parabolic trough power plant in Europe, went into operation at the end of 2008. The 50-megawatt project is located on the Plateau of Guadix in the southern Spanish province of Granada. As with the Nevada Solar One power plant near Las Vegas that has been generating power since 2007, SCHOTT Solar supplied its SCHOTT PTR® 70 receiver, the core component for this plant, as well. More than 22,000 units were shipped in total.

Three power plants that are completely identical in terms of their construction are being built all at once on the Spanish plateau. Work on AndaSol 2 is well underway, while efforts to build AndaSol 3 commenced during the third quarter in 2008.

Each phase of construction takes up a two square kilometer area. All three power plants are to generate around 180 gigawatt hours of power per year, around as much as 200,000 people consume.

Two salt storage tanks each will make it possible for electricity to continue to be produced even up to 7.5 hours after the sun has set. The Solar Millennium AG, with its subsidiaries in Erlangen, Germany, is the developer of the approx. 300 million euro project. The operators are the Spanish acs-Cobra Group and Solar Millennium.

But, how does a receiver work? Sunlight is concentrated by around 80 times by a parabolic mirror onto the roughly four- meter long solar receivers from SCHOTT. The specially coated stainless steel absorber tubes are vacuum insolated by a glass cover tube that has been coated with an anti-reflective layer to minimize heat losses. In this absorber tube thermal oil is heated up to as high as 400 degrees Celsius. This produces the steam that, in turn, generates power with the help of a turbine.
Source: SCHOTT solar
The dimensions of each AndaSol power plant are rather daunting: The mirror surface makes up more than 510,000 square meters. The troughs form 156 rows that are each 600 meters in length. Four units 150 meters in length that are capable of moving independently each form one row. And each movable unit consists of 12 collector elements. These are twelve meters long and three receivers from SCHOTT are aligned along their respective caustic lines.

The receivers for AndaSol 1 and 2 were supplied by the csp site in Mitterteich, Germany. For AndaSol 3, production capacities are now available at the new facility in Aznalcóllar, near Seville.

The future prospects for Concentrated Solar Power (CSP) all over the world could hardly be any better: An area of around 300 by 300 kilometers in the Sahara, for example, would theoretically suffice to cover the global demand for power using this technology. In the U.S., additional csp power plants are planned not only in Nevada, but all across the entire South West. There are also plans and projects for the region around the Mediterranean, in Egypt, for example.

The race for subsidies is now going on in Spain. The feed-in tariffs for csp power plants are capped at 500 megawatts until 2010. As soon as 85 percent of this has been linked with the grid, there will be a grace period of at least twelve months. So, there is reason for hope that between 700 and 900 megawatts will actually get to enjoy the incentive of 26.93 cents per kilowatt hours for 25 years.

The Spanish Government is expected to approve the legis­lation on the compensation that will follow it in 2009. The ­industry strongly expects Spanish politicians to continue to support this technology.