Edinburgh-based Gravitricity and Arup will collaborate on delivering a complete system design and commercial feasibility report for the idea, as well as identifying a potential site for their underground hydrogen store. The design will also include integration with gravity energy storage and inter-seasonal heat.
If successful, the project could be selected to enter Phase 2, where the partners would build a scale demonstrator in the UK. This would involve sinking a concrete lined vertical underground shaft with a domed cap to create a demonstration pressurised hydrogen storage vessel.
In a statement, Sally Molyneux, Gravitricity’s hydrogen and thermal storage lead, said: “If green hydrogen is to become a mass market fuel of the future – for example for providing heat to industry or powering heavy vehicles – then we need to find ways to store it safely and in large quantities close to where it is needed.
“Storing hydrogen in underground shafts is intrinsically safer and less obtrusive than above ground options and is a solution that does not require unique geology such as salt caverns. We believe Gravitricity’s innovation is a scalable storage method which is cost effective, extremely durable, and can be implemented everywhere.”
Longer term, the partners believe the shafts can also be used for fast response electricity storage, using Gravitricity’s solid weight technology which raises and lowers heavy weights in a shaft.
In addition, the shaft’s gastight lining will in future incorporate heat exchangers for inter-seasonal heat storage. Adding heat exchangers to the shaft lining would create a very large ground source capable of feeding a network of heat pumps in the surrounding area.
Last summer Gravitricity commissioned and operated a grid-connected 250kW demonstrator in Leith, Edinburgh, and now plan to build a full-scale project in a decommissioned mine shaft in mainland Europe.