One square kilometre of desert is sufficient to supply about 100 000 households with 250 million kilowatt-hours of electricity per year. Solar-thermal power plants, which use the concentrated rays of the sun to generate electricity, can make a big contribution to future energy generation. According to current studies, more than 15% of European electricity requirements could be produced from concentrating solar power systems in 2050.
Researchers at the DLR Institute of Technical Thermodynamics are testing ceramic materials (pictured here), molten salts, concrete and natural stone for use as thermal storage media.
By incorporating thermal energy storage, solar thermal power plants are able to provide electricity as required, even at night-time and during periods of low sunlight. DLR researchers use the 10-kilowatt test facility to examine heat storage at temperatures ranging up to 400 degrees Celsius. The storage container can be operated with different storage mediums based on salt to develop latent heat storage, and molten salt storage.
DLR (CC-BY 3.0).
High-temperature storage could accelerate the deployment of renewable energy and also provide for more flexibility and greater efficiency in industrial processes as well as conventional power plant applications. The core of the 'HOTREG' experimental plant at the DLR Institute of Technical Thermodynamics is a five-metre-high storage unit. With the reconfigurable test unit for investigation of thermal storage, researchers can test various storage concepts, operating methods and materials.
Reconfigurable thermal storage test unit with removable inner container.
The salt-based latent heat storage system works using a phase transition. At 305 degrees Celsius, the salt absorbs energy by transitioning from a solid to a liquid state. Latent heat is 'hidden' energy. Energy is accumulated as the storage medium changes phase from solid to liquid.