As a dependable technology, solar thermal power stations can play an important role in transitioning the power grid to renewable energy sources. In contrast to other renewable sources, they supply electricity on demand and can stabilise the grid. This fact was emphasised in the study produced by EASAC (the European Academies Science Advisory Council), a body set up by leading European scientists and lead by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR). On 7 November 2011, this study was handed over to the German Federal Minister for Education and Research, Annette Schavan, in Brussels. In solar power stations, mirrors are used to concentrate sunlight and convert it into thermal energy). This process enables temperatures of more than 1000 degrees Celsius to be achieved, which can be used to generate electricity, among other things.
DLR (CC-BY 3.0).
In parabolic trough solar power plants, sunlight is concentrated onto a receiver tube located at the focus of the parabolic mirrors. The sunlight is then converted into heat. The heated oil heats water, producing steam that drives a turbine to generate electricity.
In Dish-Stirling systems, a parabolic mirror concentrates solar radiation into a focal point, where the Stirling motor is placed. Heat energy is transformed into mechanical energy by the Stirling motor. As a general rule, a generator then uses the mechanical energy to generate electricity.
With KONTAS (Konzentrator-Teststand Almeria Spanien), energy researchers from the DLR Institute for Solar Research will be able to test parabolic trough collectors up to 20 metres long at any angle to the Sun and measure their efficiency. The new test stand can be used to evaluate complete modules of parabolic trough collectors as well as individual components such as mirrors and absorber pipes. DLR operates the new test stand at the Plataforma Solar de Almería with CIEMAT.
With KONTAS, researchers have expanded the techniques and possibilities for testing solar-thermal power plant components even further.
A researcher from the DLR Institute for Solar Research tests a mirror for a solar-thermal power plant. DLR has developed its own test facilities and methods for verifying quality. In important areas, they have succeeded in developing internationally recognised quality standards.
At the Jülich site, set up on an area covering about eight hectares, are 2153 moving mirrors (heliostats). These mirrors track the path of the sun and concentrate the solar radiation on a receiver, about 22 square metres in size, installed at the top of a 60-metre-tall tower. The receiver is made of porous ceramic elements permeated by ambient air. This heats the air up to about 700 degrees Celsius and then, it releases this heat to the water-steam cycle. The steam generated here drives a turbine, which produces electrical power.
At the Jülich site, set up on an area covering about eight hectares, are 2153 moving mirrors that concentrate the solar radiation onto a receiver atop the 60-metre tower.
Studies have demonstrated the vast potential of solar power; for example, the deserts on Earth receive more solar energy in just six hours than the world's population consumes in an entire year. To enable the cost-efficient conversion of solar power into electricity, solar cells and solar thermal power stations need to operate more efficiently and become much less expensive to build.
At the DLR Institute of Solar Research, scientists develop new components for solar power plants, from first principles through to pilot plants. Here, researchers can test new components for the future under power plant conditions. The solar tower in Jülich will be expanded as a large-scale test facility.
The locations of the new institute are Cologne, Jülich, Stuttgart and Almería. In Almería, researchers have been conducting research into solar power plants for 30 years. The solar tower power plant is surrounded by a mirror field that reflects solar radiation onto a receiver. The heat energy collected drives a turbine, thus generating electricity.
DLR is conducting research into energy for the future in Stuttgart, Cologne and Almeria, southern Spain. With thermal storage, the electricity production of solar-thermal power plants can be decoupled from variations in solar radiation. Solar-thermal power plants could then provide a more uniform flow of power, operating even at night or during heavy cloud cover.