ABSTRACT Subsurface storage technologies (SSTs), including geological CO 2 sequestration, underground hydrogen storage, compressed‑air energy storage and thermal energy storage, are emerging as a scalable route for industry to achieve the terawatt‑hour storage flexibility and permanent carbon removal that evolving energy systems demand. Yet prevailing design codes, investment models, and licensing regimes still assess each technology in isolation, discouraging developers from sharing pore space, surface infrastructure or access to a wider market. This article contends that co‑locating two or more SSTs within a single reservoir (or porous geological storage system) can, under the right circumstances, unlock bankable advantages by extending asset life, smoothing cash flow and lowering abandonment cost. We highlight the potential benefits of synergies based on historical evidence, field tests and modelling studies. Initially, stakeholders should focus on single‐site investigations and on modelling subsurface and surface infrastructure to systematically assess the long‐term benefits and sustainability of synergistic SST operations. This approach is crucial for future‐proofing SST sites and adapting to evolving energy landscapes, offering a resilient and economically viable path forward for the energy industry.
Mouli‐Castillo et al. (Thu,) studied this question.