The technology for the generation and use of hydrogen as a fuel is established however at present the best way to store the hydrogen is to pressurise the gas to 350 bar or higher (i.e. 350 times atmospheric pressure). This has cost and safety
considerations. Handling high pressure hydrogen requires thick and heavy metal cylinders or bulky composite cylinders. Electrolysers driven by electricity from renewables or from the grid can readily generate hydrogen but this is at low
pressures. Thus mechanical gas compressors are needed to compress the gas to above 350 bar. Such mechanical compressors are expensive and require maintenance, the storing of large quantities of hydrogen at high pressure requires blast zones. Being able to store the majority of gas at low pressure utilising metal hydride (MH) solid state stores is not only safer but it requires much less volume. Fuel cells (which convert hydrogen and oxygen to water and electricity) operate at these low pressures too, so for certain stationary applications, storing hydrogen by a low pressure MH store makes sense. This project will build a prototype to prove the viability of the technology and explore the market potential for MH stores.

This project will use an innovative metal hydride that has been developed and tested via EPSRC funded research and this combined with our latest heat management modelling will deliver the next generation metal hydride stores with reduced
materials cost, reduced complexity of balance of plant and higher efficiency. These stores will be based on a lightweight aluminium pressure vessel with a passive internal thermal management design. This will deliver a prototype "off the shelf" hydrogen store that can store at a pressure of a few bar the equivalent mass of gas to a 350 bar pressure cylinder for stationary applications yet in a smaller volumetric footprint. The metal hydride has over 2 wt% working capacity operating between 1 and 30 bar, ideal for storing gas from electrolysers and delivering to fuel cells. This is a working capacity double that of AB5 and 30% that of commercially available AB2 hydrides, but at lower raw material cost than either competitor alloy.

Potential Impact:
While an energy storage device will contribute to meeting the combined objectives of the energy trilemma, the purpose of the project is to demonstrate to the partners the economics of delivering a practical hydrogen store. If successful this will
generate economic benefits for Arcola and ITM power through offering an integrated low pressure hydrogen store with their systems, a new market for Luxfer's aluminium pressure vessel technology and a potential spin out for the UoN. Thus it has
the potential to generate jobs as well as being a clean energy storage medium. The timescale for these benefits depends on the uptake of hydrogen storage in the market. Estimates range from 3 to 10 years.

As well as economic benefits there are social and environmnetal benefits. The social benefits come from demonstration and acceptance of the use of hydrogen by the public. This is vital for the hydrogen economy whether hydrogen is used
directly or indirectly through augmenting gas supplies. The environmental benefits of using MH tanks is they store the hydrogen at low pressure which negates expensive energy inefficient mechanical compressors that require constant maintenance and improves safety. Another key benefit is the reduction of safety zone areas required for high pressure hydrogen stores. By reducing the total amount of hydrogen that is
stored at high pressure effectively reduces vital land usage due to reduced safety zone requirements. This project addresses all three aspects of the energy trillema and brings associated benefits to the UK and potentially globally. Greater deployment of energy storage at scale enables greater renewables penetration reducing carbon
emissions and increasing energy security, as well as reducing costs at the energy system level with a 25% reduction in costs projected compared to comparable existing technologies. Energy storage also helps improve grid stability by both reducing the amount of renewables exported to the grid and helping to turn renewables into a schedularised asset.