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The geological storage of hydrogen is a seasonal energy storage solution, and the storage capacity of saline aquifers is most appropriately defined by quantifying the amount of hydrogen that can be injected and reproduced over a relevant time period. Cushion gas, stored in the reservoir to support the production of the working gas, is a CAPEX, which should be reduced to decrease implementation cost for gas storage. The cushion gas to working gas ratio provides a sufficiently accurate reflection of the storage efficiency, with higher ratios equating to larger initial investments. This paper investigates how technical measures, such as well configurations and adjustments to the operational size and schedule, can reduce this ratio, and the outcomes can inform optimisation strategies for hydrogen storage operations. Using a simplified open saline aquifer reservoir model, hydrogen storage is simulated with a single injection and production well. The results show that the injection process is more sensitive to technical measures than the production process; a shorter perforation and a smaller well diameter increases the required cushion gas for the injection process but has little impact on the production. If the storage operation capacity is expanded, and the working gas volume increased, the required cushion gas to working gas ratio increases for injection, reducing the efficiency of the injection process. When the reservoir pressure has more time to equilibrate, less cushion gas is required. It is shown that cushion gas plays an important role in storage operations and that the tested optimisation strategies impart only minor effects on the production process, however, there is significant need for careful optimisation of the injection process. It is suggested that the recoverable part of the cushion gas could be seen as a strategic gas reserve, which can be produced during an energy crisis. In this scenario, the recoverable cushion gas could be owned by the state, and the upfront costs for gas storage to the operator would be reduced, making the implementation of more gas storage and the onset of hydrogen storage more attractive to investors. [ABSTRACT FROM AUTHOR]

The organisers of this month's HefmA 2014 annual conference and exhibition promise delegates "the opportunity to hear international perspectives on the current issues facing the worldwide 'family' of health estates and facilities professionals". Conference speakers will include a US-based consultant architect discussing 'a transformational change programme which has achieved up to threefold greater throughput using the existing footprint in a US Emergency Department'; the assistant director, Facilities Services, at Health Facilities Scotland, focusing on HFS's work to ensure high training standards and succession planning, former BBC war correspondent, Kate Adie, describing some of the 'extraordinary experiences' of an eventful career, and Will Whitehorn, a former search-and-rescue helicopter crewman, who later became president of 'the world's first commercial spaceline', Virgin Galactic, giving his view on technology's impact in business.