Experimental Characterization and Modelling of Geopolymers and Hybrid Materials for Solar Thermal Energy

Climate change and global warming are problems that our planet is currently leading with. Main outcomes of Climate Change Conferences all around the globe, like the COP27, deal with the reduction of CO2, the removal of inefficient fossil subsidies and the promotion of renewable energies. To achieve these goals, this work presents new cementitious materials to be used as thermal energy storage in concentrated solar power technologies. These new materials (alkaline cements and hybrids cements) avoid the use of Portland Cement (PC), whose manufacturing emits between 7% and 9% of the global CO2 emissions. These eco-efficient materials, after the exposure to high temperatures, present better mechanical properties than the ordinary mortar composed of PC, and in addition, they could offer improvements of the thermal properties (i.e., either the thermal conductivity or the specific heat). After presenting the experimental tests and data, a finite-element-based approach is implemented for simulation purposes. A parametric study is carried out to find the optimum heat exchanger configurations that maximize the thermal energy storage. In order to define the best composition of the block (i.e., material, distribution of the tubes), the systems are compared by taking into account a storage of 1100 MWh given in a parabolic trough power plant of the ANDASOL-type.