Project Summary
Presently large-scale storage of hydrogen in a net zero system is primarily in depleted gas fields. This project considers the alternative of using aquifer formations.
Aquifers offers countervailing benefits: the aquifer is at pressure at the start of storage use, so the requirement for cushion gas is reduced, and there is no risk of contamination of stored hydrogen with residual methane.
The project will assess and model the reservoir performance of known geological structures in two locations, to inform developers of hydrogen storage and identify the relative cost and performance of depleted gas fields as compared with aquifers.
Innovation Justification
The proposed project addresses the challenge of developing novel technical and market approaches to deliver an equitable and secure net zero power system. The innovation addresses the challenges of managing peak demand and stability over longer time periods, specifically seasonal storage of hydrogen.
Innovation in the project aims to develop a specific novel operational practice -- namely, the storage of large quantities of hydrogen in porous geological aquifer structures at lower cost and at least operational equivalence with storage in depleted gas fields.
At present, most focus on large scale storage of hydrogen in a net zero energy system is on storage in depleted gas fields. This project considers the alternative strategy of using aquifer formations. Depleted gas fields offer the advantage of demonstrated storage integrity, but have a very significant requirement for cushion gas (gas required to repressurise the gas field to a level at which flow rates are viable) and produced hydrogen is likely to be contaminated with methane from the depleted reservoir.
The use of aquifers offers countervailing benefits: the aquifer is at pressure at the start of storage use, so the requirement for cushion gas is reduced, and there is no risk of contamination of stored hydrogen with residual methane. However, pressure management of the aquifer may require the drilling of pressure relief wells, and demonstration of storage integrity may be more challenging.
The innovation in the project will apply laboratory-scale experimental results already derived by Cambridge University's Institute Energy and Environmental Flows ("CUIEEF") and regional and localised geological interpretations available to the British Geological Survey to evaluate known and mapped aquifer structures in the East Irish Sea and offshore Northeast England.
BGS has detailed information on the known aquifer structures in the East Irish Sea, and will catalogue critical aspects of their geology including volume, reservoir characteristics, sealing formation thickness, integrity and faulting.
CUIEEF has already undertaken lab-scale experiments to explore how injected hydrogen interfingers with interstitial formation water and how hydrogen re-produced from a storage site is mixed with produced formation water.
Progressive will work with CUIEEF to apply learnings from these experiments with the assessment of the known structures, to develop reservoir models which will characterise the likely injection and production performance, and cushion gas requirement for these structures. These structures will be assessed and subjected to a techno-economic evaluation and ranking, against a counterfactual of hydrogen storage in a depleted gas field.
Impacts and Benefits
Financial - The project will identify whether aquifer storage of hydrogen is lower cost than the counterfactual. This will allow network operators to select the least cost storage strategy, thereby achieving reductions in the cost of operating the network.
Financial - By adopting least cost hydrogen storage, users of network services can expect to share in the lower costs delivered by the network operators, and we would expect these to be passed on to customers.
Environmental - direct and indirect CO2 savings per annum. The techno-economic evaluation will include an assessment of the direct and indirect CO2 emissions impacts of large scale storage of hydrogen in aquifers against the counterfactual of depleted gas field storage. Combining cost and emissions assessments from each storage strategy, the preferred strategy from both cost and emissions perspectives will be assessed.
Revenues - The availability of large scale storage will provide network service users with security of supply of hydrogen, through the year, and independent of short term supply disruption (which may arise from low wind output impacting green hydrogen output or restricted natural gas feedstock availability reducing blue hydrogen output). This will give them improved access to existing revenue streams.
Revenues - Users of network services may be able to use low cost large scale storage of hydrogen to develop revenue-generative services and products. For example, network users may be able to offer hydrogen supply contracts underwritten by secure hydrogen supply from storage, providing customers with secure supply at a known cost.
New to market --The availability of low cost large scale hydrogen storage will enable the development of new products, processes and services. Large scale storage permits the development of different hydrogen supply offers, and this project will identify the least cost strategy for such large scale storage. The requirement for low carbon dispatchable power in a net zero energy system, to meet demand when renewables output is low for an extended period, is critical to the operation of that system.
