Meeting inter-seasonal fluctuations in electricity production or demand in a system dominated by renewable energy requires the cheap, reliable and accessible storage of energy on a scale that is currently challenging to achieve. Commercially mature compressed air energy storage (CAES) could be applied to porous rocks in sedimentary basins worldwide where legacy data from hydrocarbon exploration are available, and where geographically close to renewable energy sources. Here we present a modeling approach to predict the potential for CAES in porous rocks. By combining these with an extensive geological database we provide a regional assessment of this potential for the UK.

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To meet carbon emissions reduction targets heat and transport need to be decarbonised. Hydrogen is being considered as a flexible energy vector that could play an important part in this endeavour. With demonstration projects on the rise it is crucial to identify suitable odorants to ensure, safety regulations are met and public acceptance gained. Specifically, this work investigates the use of sulphur based odorants currently in use in the UK and Europe, alongside sulphur-free and experimental ones, for use in a 100% hydrogen gas demonstration network in the UK. Gas samples odorised with five different odorants are analysed to determine odour detection threshold, the odour intensity, its hedonic tone and character. The tests are performed by an accredited laboratory following EU standards. The results show that four odorants meet requirements as stenching agents for use in UK gas distribution network, whilst one, 5-ethylidene-2-norbornene, fails to demonstrate an unpleasant odour.

General rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s) and / or other copyright owners and it is a condition of accessing these publications that users recognise and abide by the legal requirements associated with these rights. Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorer content complies with UK legislation. If you believe that the public display of this file breaches copyright please contact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately and investigate your claim. Time-lapse gravity surveys are a potential low cost method for detecting CO2 migration 10 from a storage site, particularly where accumulation within an overlying aquifer is predicted. 11The modelled storage system consists of a storage reservoir (1000m crestal depth) 12 and an overlying aquifer at variable depths (50 -750 m crest), within a simple dome 13 structure. In leakage scenarios, these are connected by a single vertical permeable 14 pathway. CO2 leakage was simulated using the Permedia® CO2 simulator, and a gravity 15 model calculated to compare a leakage and a non-leakage scenario. Time-lapse gravity 16 surveys are likely to be able to detect CO2 leakage with CO2 accumulation within an aquifer 17 to depths of at least 750 m, at least within an actively subsiding sedimentary basin where 18 sandstones are expected to have high porosities at shallow burial depths. For a high relief 19 structure in which the CO2 accumulates, the change in gravity cannot be used to detect the 20 location of the leakage pathway as the measured gravity anomaly is centred on the 21 geological structure. The first detection of leakage is possible after 11 -15 years of leakage, 22 though a maximum of only c. 1 % of injected CO2 will have leaked at this time. 23 24

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Decarbonisation of road transport is essential in a Net-Zero transition. Currently neither hydrogen nor electricity are inevitable. Is electrification the single obvious solution, or is a combination with hydrogen more functional and cost-effective? Scotland makes a good exemplar of transport Transition, with a defined geography, a world leading Net-Zero ambition, and proven pathways for generating large amounts of renewable energy. We identified essential elements of the new transport systems, including CapEx and OpEx and emissions through transition. We developed five scenarios modelled for transition around varying the pace of change for some or all vehicle classes. Monte Carlo simulations investigated the emissions, vehicle mixes, construction speed, and costs.CapEx to install generation and refuelling infrastructure for electricity or for hydrogen favours hydrogen by a substantial margin, with multi £Bn cost-reductions. Untaxed OpEx costs favour electricity, such that whole system costs are broadly similar for any mix, although untaxed per-km fuel costs for either should be lower than hydrocarbons. User experience, energy storage, vehicle characteristics, social factors, use of natural resources – almost all favour increased hydrogen use. Hydrogen interseasonal storage at national scale is feasible in salt caverns, with re-purposing of the transmission pipeline grid, and huge scale-up of generation; interseasonal electricity storage does not exist at national scale, and significant electrification penetration requires immense infrastructure upgrades.A no regrets action is the rapid deployment of hydrogen infrastructure for buses, trucks and large fleets, with enough to facilitate hydrogen car ownership. Jobs could be created and maintained locally in hydrogen manufacturing, installation and servicing.