Traditional approaches to estimate CO₂ solubility in liquids rely on free-energy based methods such as Bennett’s Acceptance Ratio (BAR). These techniques compute the excess chemical potential of CO₂ and subsequently Henry’s constant. While accurate, they are computationally demanding and therefore unsuitable for high-throughput screening. In this work, we propose a faster, qualitative approach that focuses directly on CO₂-solvent interactions. Our method is 10–100× more efficient than free-energy calculations, making it attractive for rapid solvent evaluation. For ionic liquids (ILs), it is well established that CO₂ interacts more strongly with anions than with cations. We quantify this interaction strength by measuring the association lifetimes between CO₂ molecules and their nearest anions. We then assess the correlation between these lifetimes and experimentally known CO₂ solubilities across different ILs. Longer association lifetimes reflect stronger CO₂-anion affinity, leading to better retention and higher solubility. For molecular liquids, we study the dissolution and effusion of CO₂ through a liquid slab exposed to a CO₂ environment. From a single simulation, we obtain the number density profile of CO₂ within the slab and track its transport behavior. Unlike free-energy based methods, our framework extracts meaningful solubility-related descriptors from a single trajectory. This enables both high-throughput screening and qualitative comparison of solvents with a fraction of the computational cost.
