Material issues for concentrated solar power (CSP)

Kurzfassung

By concentrated solar radiation, thermal energy can be obtained to be used for power generation or for thermal process engineering. However, there are still a number of material issues to be resolved: Specific functional demands must be fulfilled and long-term stability under cyclic thermal load and harsh environmental conditions is required. In case of open volumetric solar absorbers ubiquitous mineral dust may deposit on hot SiC surfaces. The influence of mineral dust on absorbance and corrosion was investigated in detail. Refractive ceramic particles can be used in specially designed particle receivers. High absorbance, sufficient mechanical stability and low production costs are the crucial properties. Pros and cons of commercial alumina-based pellets ("Proppants") and possible alternative raw materials are discussed. Heat storage and related material challenges is another important topic in CSP technology. A new cost-cutting approach for salt-based heat storage is "diluting" the salt melt with cheap inorganic materials. Beside specific heat capacity and costs, stability against highly corrosive nitrate melts is the most important property of such filler materials. Another approach for heat storage is heat-absorption and release, respectively, by reversible chemical reactions. Manganese-based redox systems are promising materials for heat storage. Thermodynamic conditions, microstructure and its influence on redox kinetics will be discussed.