Global primary aluminum smelters' CO2 mitigation potential and targeted carbon-neutral pathways

Abstract

The expansion of aluminum smelter capacity generates high CO₂ emissions, exhibiting spatiotemporal diversity due to diverse processing routes and technologies. Despite extensive discussions on macro abatement options, facility-specific mitigation potentials and decarbonization strategies remain unclear, which cumulatively affects the progress towards global 1.5 °C and 2 °C warming control targets. This study develops a carbon footprint inventory of 163 primary aluminum smelters in 2022 and analyzes current emission structures concerning location, age, production, and input-output. Then adjust available technologies and efficiencies to match global plant-level decarbonization routes. The potential contributions of each strategy are finally quantified, accounting for significant geographic variations in emissions, thereby supplementing tailored technology transformation pathways for smelters across nine focus regions. The results show that: (1) Young smelters, predominantly in developing regions, are crucial for abatement. Rapid retrofits ahead could save CO₂ budgets by 0.6–28.56 Gt, potentially delaying excess emissions under climate targets, particularly with comprehensive retrofits. (2) The paramount technical retrofitting for carbon neutrality differs regionally and evolves. Smelters in developing countries should prioritize renewable energy investment in the immediate future, succeeded by the optimization of power generation infrastructures. To liberate more emission allowances, developed countries ought to contemplate the decommissioning of aged smelters or upgrading through emerging supply-side technologies. (3) Available retrofits can facilitate the aluminum industry's contribution to the 2 °C climate target, whereas addressing the 1.5 °C target will necessitate the adoption of more innovative technologies and materials. This paper endeavors to assist global and regional smelters in developing more targeted decarbonization pathways.