Concentrated Solar Power (CSP) plants using air as heat transfer fluid in an open volumetric receiver can have high conversion efficiency, low cost of thermal energy storage as well as the potential of efficient electricity storage integration, when combing the plant with compressed air energy storage. Participating in two currently running research projects, namely SUNFLOWER (Sustainable near-net shape fabrication of low environmental impact receiver materials) and ASTERIx-CEASar (Air-based solar thermal electricity for efficient renewable energy integration & compressed air energy storage), Fraunhofer IKTS and the collaborating partners work on the improvement of the solar absorber material. The absorber structure that receives the concentrated thermal energy and transfers it to the air, is a key component in this complex system. It must be characterized by a high thermal conductivity, high thermomechanical and chemical stability, low pressure drop and high durability – all these at lowest possible cost. Different absorber structures such as foams, honeycombs and additively manufactured fabrics have already been in focus of research in the past. While a low raw material consumption, the reduction of the overall CO2-footpint, and the achievement of a high property level of the absorber structures is in focus of the SUNFLOWER project, the activities in the ASTERIx-CEASar project are dedicated to the reduction of production effort and maintenance costs by identifying the most efficient absorber design. Of particular interest are high temperature stable materials such as Iron-Chromium-Aluminium-Alloys and Silicon Carbide. An overview about the developments in the past and the ongoing research of open-celled absorber structures made of Silicon Carbide and Iron-Chromium-Aluminium-Alloys will be given.
The authors acknowledge the funding by the European Union and the national funding agencies.