Steam‐Based Thermal Remediation in Cold‐Region Soils: Multiscale Mechanisms, Conditional Controls and Modelling Limits

ABSTRACT

Steam‐based thermal remediation is increasingly applied to hydrocarbon‐contaminated soils in cold and permafrost regions, but its performance varies markedly across laboratory and field conditions due to coupled thermal, hydraulic, mechanical and physicochemical processes. This review develops a multiscale framework integrating pore‐, fracture‐ and field‐scale mechanisms controlling steam‐based thermal remediation in frozen soils. At the pore scale, freeze–thaw cycling modifies pore connectivity, unfrozen water distribution and contaminant mobility. At the fracture scale, fractures may enhance heat transfer or induce thermal short‐circuiting depending on their connectivity and evolution. At the field scale, subsurface heterogeneity, ice content and operational parameters jointly determine heating efficiency and contaminant removal. The review further evaluates the capabilities and limitations of multiphysics coupling models, highlighting uncertainties caused by parameter non‐uniqueness, scale mismatch and limited field observability. Optimization approaches, including adaptive steam injection, hybrid remediation and low‐carbon energy integration, are discussed as site‐dependent strategies. This review provides a multiscale perspective for interpreting, modelling and optimizing steam‐based thermal remediation in cold‐region environments.