India’s pledge to achieve net-zero emissions by 2070, along with rapidly growing energy demand and large-scale renewable integration, makes long-term and seasonal energy storage indispensable. While electrochemical batteries and surface pumped hydro systems remain important, their scalability, duration limitations, and land footprint hinder their ability to support a deeply decarbonized energy system. In contrast, underground energy storage (UES), which includes geological storage of hydrogen, natural gas, compressed air, and carbon dioxide, offers unparalleled capacity, duration, and strategic flexibility. Critically, UES is not a traditional infrastructure problem. This is a geological system challenge that requires reliable reservoir control, cap-rock integrity under cyclic pressure, fault stability, groundwater conservation and continuous monitoring over decades. India’s geological endowment, consisting of mature sedimentary basins, extensive basalt provinces and abandoned mining infrastructure, can provide a strong foundation, but only if developed through rigorous geophysical science and sustained research investment.
Union Budget Allocation of Government of India ₹Rs 20,000 crore over five years for Carbon Capture, Utilization and Storage (CCUS), representing an important recognition of the role of the subsurface in India’s climate and energy strategy. Geological CO₂ storage underpins industrial decarbonization, but its importance goes far beyond emissions reductions. The CCUS establishes the necessary technical, institutional and regulatory basis for all types of underground energy storage. The scientific principles governing CO₂ storage in geological formations, for example, reservoir characterization, seal integrity, injection well design, pressure management, plume tracking and long-term risk mitigation, are basically the same as for hydrogen, synthetic gas or compressed air storage. National assessments indicate that India’s geological CO₂ storage potential, spanning deep saline aquifers, depleted hydrocarbon reservoirs and continental flood basalts, would amount to several hundred million tonnes. These formations, subject to appropriate geochemical and geomechanical assessment, can also host other energy vectors, reinforcing the need for an integrated subsurface storage framework rather than siled projects. Furthermore, CCUS deployment accelerates the development of shared infrastructure such as pipelines, compressors, injection wells, monitoring networks and importantly, regulatory processes for underground injection and long-term liability. International experience shows that these frameworks are largely technology-agnostic and transferable to different gases. Therefore, India’s emerging CCUS roadmap provides a timely opportunity to mainstream underground energy storage under the national energy plan.
India’s sedimentary basins contain depleted oil and gas fields and deep saline formations that are theoretically suitable for underground energy storage. Depleted reservoirs are particularly attractive due to their proven trapping mechanisms, known pressure history, and existing subsurface datasets. However, in comparison, hydrogen storage introduces additional geological complexity. Hydrogen’s small molecular size, high diffusivity, and potential for geochemical and microbial reactions demand exceptionally strong cap rocks, careful pressure cycling, and high-resolution fault characterization. Basin-scale studies suggest large theoretical storage capacity, but safe deployment depends on advanced subsurface imaging, rock physics analysis, reactive transport modeling, and accurate monitoring. Mechanical storage concepts, such as underground pumped hydro and gravity-based systems, further expand India’s UES portfolio. These options minimize surface land conflicts, but depend heavily on geophysical and geotechnical assessment of rock-mass stability, seepage pathways, and long-term deformation behavior.
The success of underground energy storage in India will highly depend on the capabilities of the geophysical community in academia, national laboratories, industry and professional bodies such as the Indian Geophysical Union (IGU).. Geophysicists have a decisive role in:
- Basin-scale screening and site selectionUsing seismic, gravity, magnetic, and other geophysical data for integrated basin modeling to rank candidate structures.
- Reservoir, basement, overburden and seal characterizationWhich includes assessment of heterogeneity, fracture networks and cap-rock integrity throughout the storage complex through advanced imaging techniques and rock physics.
- Monitoring, Verification and Risk MitigationEmploying time-lapse geophysical data, microseismicity and surface deformation measurements.
- Induced Seismicity and GeomechanicsDefining safe operating pressure envelopes and communicating regulatory limits.
- Integrated Modeling and Uncertainty AnalysisCombining geophysical, geological, geochemical and engineering datasets.
Without sustained leadership from the geophysical community, UES projects risk becoming low-character, over-engineered, or socially controversial.
The ultimate impact of underground energy storage should not depend on imported solutions, but on indigenous innovations and sustained research. Experts have argued that India’s industrial ecosystem has often prioritized the import of deep technology rather than its own manufacturing, leading to a lack of domestic R&D capacity. One cautionary example cited was the shelving of a lithium-battery initiative by a major Indian firm due to unavailable foreign technology, while a small Finland-US startup successfully demonstrated solid-state batteries through close academia-industry collaboration and patient investment.
UES research will need the same ingredients: long-horizon funding, tolerance for early failure, and deep integration between universities, national laboratories, and industry. Research on injected gas (hydrogen)-rock interactions, cap-rock integrity, multiphase flow, and monitoring technologies will inevitably encounter setbacks at laboratory or pilot scale, but these should be treated as learning milestones, not failures. India has to develop the belief that real research can happen here.
Education must play a central role in building India’s UES capacity. Earth scientists and engineers should lead curriculum development and research programs that include subsurface energy storage, reservoir simulation, geochemical monitoring, induced seismicity, and risk assessment. The recent Indian experience underlines this need. The NTPC-IIT Bombay CO₂ storage initiative, which includes India’s first CO₂ injection test well, required detailed mapping of coal-bed reservoirs, high-pressure well design, seismic monitoring and stress-testing of injection protocols. Experts associated with the project emphasize indigenous technology development, careful monitoring of underground conditions, injection pressure, well integrity and seismic response for the success of such a project. This requires a national storage atlas and structured feasibility and risk assessment, which can provide a blueprint for future UES initiatives in India. As a first step, expanding such collaboration by linking NTPC, GAIL, ONGC, Oil India, Coal India and other public sector entities with universities, national laboratories and consulting firms with strong technical and managerial capabilities will be important for building both technical expertise and managerial capacity in underground storage.
Regulation must evolve in parallel with technology. Clear, transparent rules for siting, permitting, monitoring and long-term liability are essential to avoid project delays and public opposition. The experience of CCUS globally shows that uncertainty in permissions and liability can hold back even well-designed projects. India’s CCUS roadmap and emerging regulatory framework must clearly accommodate multiple gases and storage modes. Therefore, geological survey agencies, groundwater authorities, mining regulators and other stakeholders should get involved quickly. Geologists must be integral to these discussions, ensuring that geo-hazard risks such as seismicity, aquifer connectivity and material compatibility are proactively addressed rather than retrofitted.
Underground energy storage is a scientific and strategic imperative for India’s clean-energy future. This directly links climate mitigation to energy security. However, realizing this capability requires more than hardware deployment.
This demands continued investment in subsurface R&D, geophysical capacity-building and regulatory framework based on Indian geology. The geophysical community has an important role in mapping storage resources, quantifying uncertainty, monitoring performance, and shaping evidence-based regulation. By leading multidisciplinary efforts across science, industry and policy, Indian geology can ensure that energy is stored where it belongs, “underground”, and that India’s energy transition is secure, resilient and self-reliant.
This article is written by Pradeep Singhvi, Executive Director, Energy and Climate Practice, Grant Thornton India LLP and Nimisha Vedanti, Chief Scientist, CSIR, National Institute of Geophysical Research.
