Solar Electricity on a Large Scale Linear Fresnel Collectors for Solar Thermal Power Stations in a Practice Test

In addition to photovoltaics, solar thermal power stations are central to solar electricity generation. Over the past years, Fraunhofer ISE has performed research to optimize the components of such power stations and has carried out theoretical investigations on new concepts. In cooperation with industry and research partners, a new demonstration plant is being constructed under the direction of MAN Ferrostall Power Industry GmbH, whose goal it is to commercialize linear Fresnel collectors for use in solar thermal power stations.

Fraunhofer ISE presents concepts and components at the Stand of the Fraunhofer Alliance Energy at the Hanover Trade Fair this year from 16-20 April.

In conventional solar thermal power stations (parabolic trough system), sunlight is focused on a solar-selective absorber pipe by means of mirrors. The thermal oil flowing in the pipe is heated by the intense solar heat, and the resulting steam produced in the heat exchanger is converted to electricity by means of a turbine and generator. Both the classical parabolic trough system as well as the new concept of Fresnel systems with secondary mirrors are classified under linear concentrating systems. Particular to the Fresnel system are flat mirrors which are controlled as strings and track the sun. The solar radiation is focused on a central absorber pipe with a highly selective coating and which is situated above the reflector field. The components required for this system are, for the most part, inexpensive standard items. They are available world-wide, allowing a high local share of added value, which gives this technology an advantage over competitive technologies. In addition, Fresnel technology is not sensitive to wind loads and allows parallel land use to a large extent.

Fraunhofer ISE has contributed greatly in making the key components such as the absorber pipe, the secondary reflectors, primary reflector array and their control ready for operation. Based on theoretical investigations and the specific conditions found in sunny climates, Fraunhofer researchers have calculated that the electricity production costs will not rise above 0.12 €/kWh.

The next step is the technical verification under real operating conditions. For this purpose, a 100m long collector string is being constructed as a test and demonstration project at the Plataforma Solar de Almería in southern Spain. Both Fraunhofer ISE and the German Aerospace Center (DLR) are measuring the optical and thermal characteristics of the system. The industry partner MAN Ferrostaal Power Industry GmbH and Solar Power Group GmbH are in charge of the commercialization of this technology.

As well as the market introduction of Fresnel collector systems, the partners in Almeria have also made it their goal to develop new power plant concepts for the small and medium power range. In particular, these concepts aim to have a low investment risk and also to make use of combined heat, cooling and power plants. As a result, new markets open up for manufacturers of concentrating collectors and heat engines, especially in southern Europe, North Africa and the Middle East.

The construction of the power stations in Almeria is sponsored by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. In the expert report “Welt im Wandel” put out by the Scientific Committee of the Federal German Government for Global Climate Change, the potential of renewable energies and their contribution to the future energy supply are reported. www.wbgu.de

Hanover Trade Fair, 16-20 April 2007
Stand of the Fraunhofer Alliance “Energy”
Hall 13, Stand E 27
Text of the PI and Photos can be downloaded from our web page: www.ise.fraunhofer.de
Contact Persons for Further Information
Project Leader
Dr. Werner Platzer, Fraunhofer ISE
Phone: +49 (0) 7 61/45 88-51 31
Fax: +49 (0) 7 61/45 88-91 31
E-Mail: Werner.Platzer@ise.fraunhofer.de