Aluminium-Redox-Cycles for the Production of Heat and Electricity in Buildings based on Renewable Energies
Abstract
Renewable metal fuels have great potential to act as a sector coupling seasonal energy storage. Renewable electricity can be generated in summer, transformed and stored in a metal fuel without losses as long as desired, and provide decentralized heat and electricity any time, at any place. Aluminium as an energy carrier is of interest due to its high volumetric energy density (23 MWh∙m-3). Therefore, the production of heat and hydrogen from seven different Al recycling streams was analyzed and a conversion efficiency of close to 100 % was reached for all of them. However, some of the obtained solid reaction products showed metal impurities, which require a purification process in order to close the material cycle. It was estimated that the concept provides a seasonal energy storage solution with “storage” costs in the range of 9 €-cts per kWh. Additionally, life-cycle greenhouse gas (GHG) emissions of all studied aluminium-redox-cycles were substantially lower when compared to natural gas mini CHP plants for the same amount of energy (heat and power) produced.