Lab-on-a-chip insights: advancing subsurface flow applications in carbon management and hydrogen storage

The transition to sustainable energy is crucial for mitigating climate change impacts, with hydrogen and carbon storage and utilization technologies playing pivotal roles. This review highlights the integral and useful role of microfluidic technologies in advancing subsurface fluid dynamics for carbon capture, utilization, and storage (CCUS), enhanced oil recovery (EOR), and underground hydrogen storage (UHS). In particular, microfluidic platforms provide clear and insightful visualization of fluid-fluid and fluid-solid interactions at the pore scale, crucial for understanding and further optimizing processes for CO₂ sequestration, hydrogen storage, and oil displacement in various geological formations. We first discuss the development of lab-on-a-chip devices that accurately mimic subsurface conditions, allowing detailed studies of complex phenomena including viscous fingering, capillary trapping, phase behavior during CCUS and EOR processes, and the hysteresis effects unique to hydrogen storage cycles. We also discuss the dynamics of CO₂ gas and foam in enhancing oil recovery and the innovative use of hydrogen foam to mitigate issues associated with pure hydrogen gas storage. The integration of advanced imaging, spectroscopic techniques, and machine learning (ML) with microfluidic experiments has enriched our understanding and opened new pathways for predictive capabilities and operational optimization in CCUS, EOR, and UHS applications. We further emphasize the critical need for continued research into microfluidic applications, e.g., incorporating state-of-the-art ML to optimize microfluidic experiments and parameters, and UHS enhancement through favorable microbial activities and suppression of reactions in H₂ foam, aiming at refining storage strategies and exploiting the full potential of these technologies towards a sustainable energy future.