Towards the minimum equivalent carbon emission of soil thermal desorption remediation by post-combustion carbon capture.

Current research on carbon emission reduction in soil thermal remediation primarily focuses on lowering system energy consumption and enhancing process efficiency, yet direct emission reduction strategies have not garnered sufficient attention and achievable reductions remain limited. This study innovatively proposes coupling soil thermal remediation with carbon capture to achieve deep emission reductions through source-level CO2 capture. Comprehensive assessments of energy consumption, exergy efficiency, and carbon emissions were conducted for three systems: Ex-Situ Thermal Desorption (ESTD), In-Situ Thermal Desorption (ISTD), and In-Situ Thermal Desorption-Self-Cleaning Combustion (ISTD-SCC). Results indicate that the exergy efficiencies of all three technologies are significantly constrained by high irreversibility in methane combustion and heat transfer processes. Notably, ISTD demonstrated the lowest energy consumption (90% thermal energy contribution), minimal carbon emissions (73.3% attributed to methane combustion), and the highest exergy efficiency among the technologies evaluated. Analysis of the carbon capture process integrated with ISTD revealed a critical inflection point at a 93.8% capture rate, corresponding to the global minimum of total system emissions-a 40.9% reduction compared to the baseline (190.20 kg CO2eq/m3) without capture. Further analysis showed that beyond this capture threshold, steam demand for solvent regeneration surges drastically, inducing significant indirect emissions that offset decarbonization benefits. This integrated system provides a crucial theoretical foundation and key technological pathway for the low-carbon transformation of soil thermal remediation.