Geological hydrogen storage: Current status, research frontiers, and the path to large-scale deployment

Geological hydrogen storage (GHS), involving subsurface formations like salt caverns, depleted reservoirs, and aquifers, offers a scalable solution for long-term, large-capacity hydrogen storage, crucial for a decarbonized energy system reliant on clean energy carriers like hydrogen. This review analyzes the current state of GHS research, synthesizing foundational and recent literature. We examine suitable geological formations, storage mechanisms, technical, economic, and environmental challenges. Crucially, we contextualize GHS within the broader energy landscape, considering CO2 emissions, renewable energy (solar and wind), and particularly, green hydrogen production. While primarily a comprehensive synthesis of existing knowledge, this review critically assesses the current state and identifies key research frontiers, offering a structured overview valuable for researchers and policymakers in this rapidly developing field. Although GHS is vital for a future hydrogen economy, its immediate large-scale deployment isn't justified by current low green hydrogen production levels. The immediate priority is accelerating green hydrogen production. Simultaneously, sustained GHS research and development is essential to ensure storage readiness when production increases. Key research areas include optimizing site selection, understanding geochemical/microbial interactions, developing advanced models, addressing safety/environmental concerns, and overcoming engineering challenges. Proactive planning, strategic investment, and ongoing research are vital to navigate the uncertain timing of large-scale GHS deployment and realize its full potential in a sustainable energy future.