Exhausted North Sea oil and gas fields may offer viable underground sites for hydrogen storage, a finding that Durham University researchers say could help reduce Britain's reliance on gas-fired electricity generation.
Under a high-storage pathway, the research projects underground reserves accumulating 3,659 TWh of capacity by 2040, a volume equivalent to over seven years of the nation's anticipated electricity consumption at that point. That figure draws on a combination of exhausted offshore reserves and expanded salt-cavern storage capacity.
Approximately 2,582 TWh is sourced from exhausted reserves across the Irish Sea, Southern, Central, and Northern North Sea regions, while the balance is expected to derive from prospective salt-cavern storage projects. The study frames this as a maximum-capacity storage assumption rather than a projection of what the UK will necessarily construct.
The distinction is notable given that Britain's hydrogen storage approach has so far been weighted towards salt cavern facilities. Rough, the nation's largest offshore gas-storage facility, is undergoing conversion to hydrogen storage, yet depleted reservoirs have not been widely incorporated into government energy strategy.
One draw of exhausted reservoirs lies in their sheer size. Earlier studies had already documented considerable theoretical capacity for hydrogen storage within the UK's offshore natural gas reservoirs. Research published in Applied Energy in 2021 placed the theoretical storage potential of decommissioned UK offshore gas fields at up to 2,661.9 TWh, though the analysis found that only a limited proportion of those fields would be capable of fulfilling seasonal demand for residential heating.
Updated modelling in the Durham University research centres on adaptability within the electricity grid. The team built their model around half-hourly supply and demand calculations, incorporating fluctuations in weather patterns and projected growth in power consumption driven by electric vehicles, heat pumps, and data centres, rather than relying on yearly averages.
In conditions where storage capacity was limited, hydrogen reservoirs reached their maximum capacity, restricting how much excess renewable power could be absorbed through conversion. While the UK's expanding fleet of wind turbines generates substantial electricity during favourable weather, short-term battery storage lacks the economic capacity to bridge every extended period of reduced renewable generation. Excess electricity could be converted into storable hydrogen, which may then feed back into the grid when wind and solar output falls short over prolonged periods.
Across the scenarios reviewed, the analysis projected that natural gas could account for approximately 1% of electricity output by 2030. Among the scenarios examined, only the high-storage option removed the projected reliance on unabated conventional gas plants within the modelling framework by 2040.
Exhausted underground storage sites near offshore wind installations and established energy networks could offer adjustable capacity across seasons, though adapting them for this purpose would involve spending on drilling infrastructure, transmission lines, compression systems, and related hardware.
A study of a depleted natural gas reservoir on the UK Continental Shelf yielded technically favourable outcomes, with modelling of a cyclic-storage arrangement projecting around 82% hydrogen recovery and geomechanical behaviour within acceptable parameters for the formation examined.
Some uncertainty remains in the geological assessment. Reactions between hydrogen and subsurface fluids or rock formations, along with bacterial processes, may diminish extractable quantities or compromise the purity of the gas. A study examining chalk reservoirs beneath the North Sea determined that biological activity had the potential to deplete hydrogen stores, though projected annual losses in the modelled scenario remained under 0.6%.
Individual formation evaluation is identified in the research as being required for each depleted field, rather than treating all such reservoirs as uniformly viable candidates.
The central policy challenge for the UK, as framed by the research, lies not merely in expanding renewable capacity, but in determining how much of that generated electricity can be reliably converted into dependable, dispatchable power. Underground hydrogen storage offers the potential for substantial seasonal buffering of energy supply, though realising that benefit involves simultaneous development across the full supply chain — from renewable power generation and electrolysis through to distribution infrastructure, subsurface reservoirs, and hydrogen-fuelled power plants.
The future of exhausted North Sea reserves sits at the intersection of energy infrastructure planning and hydrogen policy choices. Infrastructure previously used to extract Britain's natural gas reserves may be repurposed as part of an energy storage network capable of capturing excess wind power and releasing it during periods of low generation.
