Hydrogen Storage in Caverns – a vital component in accelerating to net-zero

This event outlines the vital importance that hydrogen storage in caverns can play in the push towards net-zero.

Towards Net Zero

Energy storage is going to be absolutely central to the timely achievement of Net Zero. That storage will have to be applied over a vast spectrum of times ranging from fractions of a second to many months – and possibly more than a year. Different sets of technology excel at different parts of that time spectrum and for very long duration storage that can charge and/or discharge continuously for weeks at a time, the clear technology favourites are based on storing fuels. Within that subset, storing pure hydrogen in caverns stands out as being the leading candidate because the transformations from primary energy to hydrogen and back to usable energy are so relatively straightforward. This event set out to elucidate some of the key challenges involved in deploying the necessary amounts of hydrogen storage in caverns.

Event summary

The event began with a keynote review of just how much hydrogen storage we are likely to need in the UK – many tens of TWh worth and possibly more. The workshop proceeded to examine how the hydrogen storage blends with largescale compressed air energy storage and other thermo-mechanical energy storage solutions much better suited to shorter (medium-duration) timescales than the hydrogen and to a first order, the same amount of energy will pass through hydrogen storage as through the medium-duration storage. The latter may be around one order of magnitude smaller in capacity than the hydrogen storage but is cycled much more frequently. Subsequently, a talk examined what potential there is in the UK for making salt caverns to store hydrogen – and in short there is much more capacity than we will need to use by 2050.

The second session of the event covered the description of the near-term project, HyNet which aims to decarbonise an industrial cluster in the north-west of England around Chester and the related project HySecure which explores how to create new hydrogen cavern storage. A short commentary followed noting that the work required to push hydrogen gas into a cavern can be several hundredths of the chemical energy contained within that hydrogen. This second session closed with a fascinating insight into social acceptance aspects of the hydrogen economy.

The third and final session comprised two more technical contributions: the first outlining why hydrogen presents very singular challenges for compression and expansion machinery and the second noting the connections between hydrogen and several aspects of Rolls-Royce business – Small Modular Reactors, large reciprocating engines for power, PEM fuel cells and, of course, aerospace. The event ended with a lively panel session containing, among other things, a near-unanimous consensus that the UK should be aiming to implement 2 TWh of hydrogen storage capacity in caverns every year between now and 2050!”

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