Potential of Aluminum as a Metal Fuel for Supporting EU Long-Term Energy Storage Needs

The EU's energy transition necessitates availability of green energy carriers with high volumetric energy densities for long-term energy storage (ES) needs. A fully decarbonized scenario considering renewable energy availability is analyzed underpinning the need for such carriers. Considering the shortcomings of Power-to-X technologies in terms of efficiency and low volumetric density, Aluminum (Al) is identified as a potential alternative showing significantly high volumetric energy densities (23.5 kWh L−1). In this paper, an Al-based long-term ES concept is investigated, taking advantage of the inherent recycling of the active species (i.e., Al2O3 to Al) coupling decarbonized Hall–Héroult process with an Al-steam oxidation for simultaneous hydrogen (H2) and heat generation. This work demonstrates an innovative lab-scale fine Al powder-steam oxidation process at ≈900 °C without use of catalysts or additives, exploiting alumina as inert material. Conducted SEM-EDX analysis on oxidized Al provides supporting evidence in favor of employed oxidation pathway, hindering tendency of aluminum oxide (Al2O3) clumping and enabling direct use of oxides in the smelting process for fully recyclability. Moreover, outcomes of XRD analyses are presented to validate the measured total H2 yields.