Abstract
Seawater mineral carbonation (SMC) offers a pathway to couple CO2 removal with stable carbonate formation, yet its scalability is constrained by system-level trade-offs: alkali-source routes incur high upstream burdens, while electrochemical pathways eliminate reagents at the expense of electricity and capital intensity. Here, we evaluate eight SMC pathways using a unified framework integrating life cycle assessment (LCA) and techno-economic analysis (TEA). We show that alkali-based and bipolar membrane electrodialysis (BMED)-driven routes are limited by distinct bottlenecks. To address this, we propose various integrated configurations, including INT2 that decouples alkalinity generation from ion recovery by producing Na2CO3 via BMED and using it to precipitate Ca2+/Mg2+ from seawater. INT2 delivers the lowest energy demand among electricity-driven options and requires ∼63% renewable electricity to achieve net-zero emissions. Techno-economic-environmental results further highlight the critical role of product valorization, particularly MgCO3·3H2O and CaCO3, in offsetting costs, with INT2 exhibiting the most robust overall performance. These findings underscore that the viability of SMC hinges on system-level integration.
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•Establishes a unified LCA-TEA framework for evaluating SMC pathways.•Provides a consistent experimental dataset under controlled conditions.•Identifies the minimum viable market price of MgCO3·3H2O across scenarios.•Reveals renewable energy availability as the key lever for SMC scalability.