Direct air capture in low-carbon energy systems: Regeneration penalties, renewable integration, and carbon storage pathways

초록

Direct air capture (DAC) is increasingly recognized as a critical carbon dioxide removal technology for net-zero energy systems, but its large-scale deployment is fundamentally constrained by the thermodynamic penalty of separating CO2 from ultra-dilute air. This review evaluates DAC as an energy-system technology rather than as an isolated capture process, linking molecular capture mechanisms, regeneration severity, low-carbon energy supply, and post-capture carbon management. First, the physicochemical foundations of DAC are examined by comparing liquid-solvent, solid-sorbent, electrochemical, moisture-swing, membrane-based, cryogenic, and ocean-based capture routes. Second, regeneration thermodynamics are assessed by contrasting high-temperature calcination, low-temperature desorption, electrical regeneration, humidity-driven release, pressure-driven separation, and phase-equilibrium-based approaches. These mechanisms are then connected to their thermal and electrical energy penalties, operational flexibility, technology readiness, and compatibility with variable renewable and firm low-carbon energy sources. Finally, durable post-capture pathways are evaluated, with geological storage identified as the most mature endpoint for long-term carbon removal, while ocean-based storage and DAC–EOR are treated as conditional options requiring stronger verification, environmental assessment, and life-cycle accounting. By integrating the molecular capture mechanism, regeneration energy penalty, energy-source compatibility, post-capture permanence, and deployment readiness, this review establishes a mechanism-to-system framework for evaluating DAC within future low-carbon energy infrastructures. © 2026 Published by Elsevier Ltd.

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