Exploring the Environmental Sustainability of Primary Al-Air Batteries for Long-Term Energy Storage Applications

The transition toward a decarbonized energy system requires long-term energy storage (LTES) solutions capable of complementing hydrogen-based technologies. This study presents an exploratory life cycle assessment (LCA) of a primary aluminum-air battery (AAB) system as a prospective solid-state LTES option, benchmarked against gaseous hydrogen (GH₂) with underground storage and liquid hydrogen (LH₂) with cryogenic tank. The AAB is evaluated under current and prospective aluminum production scenarios across different geographic contexts, and is benchmarked against alternatives using identical supply chain and use-phase assumptions. AAB system achieves round-trip efficiencies of 29-35%, exceeding GH₂ and LH₂ by at least 2% and 10%, respectively. Consequently, GH₂ outperforms AAB across all categories on a cradle-to-use basis only thanks to underground storage, while AAB showing competitive performance it performs better than LH₂ in global warming potential (GWP₁₀₀) impact category. The conducted uncertainty analysis reveals that AAB might outperform H₂ in GWP and eutrophication potential (freshwater) under favorable conditions. Overall, the findings highlight trade-offs realizing climate benefits while mitigating resource and ecosystem impacts. Advancing low-carbon smelting, material circularity, optimized logistics, and durable low-impact components will be essential for enabling AAB to serve as a sustainable complement or partial substitute for hydrogen-based LTES in future low-carbon energy systems.