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.