Comprehensive Lifecycle Assessment of Direct Air Capture Systems for Carbon-Dioxide Removal from the Atmosphere

Abstract

This thesis evaluates the environmental performance of Direct Air Capture (DAC) technologies through a review of life cycle assessments (LCA), focusing on low-temperature systems integrated with solar energy for adsorbent regeneration.

The methodology combines ISO-standardized LCA modeling with experimental validation using silica-supported polyethyleneimine adsorbents under photothermal regeneration conditions. Three heating configurations (natural gas, solar-thermal, and hybrid solar-electric) were evaluated across diverse geographical regions.

Results show solar-based systems significantly outperform conventional systems, with potential emissions reductions up to 290 kg CO₂-eq per ton of CO₂ captured. Laboratory experiments demonstrated thermal system desorption required 3.0 GJ/kg CO₂ (0.07% efficiency), while the photothermal system required 707 MJ/kg CO₂ (0.29% efficiency), confirming photothermal regeneration's feasibility for low-energy DAC operation.

While regeneration energy dominates environmental impact, infrastructure, transport, and storage collectively contribute significantly. DAC deployment should prioritize regions with abundant solar resources and clean electricity grids, with policy frameworks incentivizing these optimal configurations.