Before any hydrogen can be blended with normal gas in the Keele network, the percentage of hydrogen that will be delivered must be approved by the Health & Safety Executive (HSE).
The HSE manage the UK Gas Safety (Management) Regulations (GS(M)R). These regulations ensure the safe use and management of gas through the gas network in the UK. GS(M)R currently restricts the hydrogen level in the UK to 0.1%. This level was set based on the supply of North Sea Gas which has naturally low hydrogen levels.
Under GS(M)R, there is a formal process allowing permission to be sought from the HSE to vary particular attributes of the gas being delivered – called an ‘exemption’. The HyDeploy team must submit a safety case to the HSE for approval. This will include the evidence collected from the laboratory testing and checks in Phase 1, alongside existing literature data and a Quantified Risk Assessment that will compare the risk of a blend with the existing base level using natural gas only. Based on the evidence, this safety case will propose the percentage of hydrogen that can be delivered safely to homes (to a maximum of 20% volume).
The HSE will evaluate the exemption application and make a decision about whether an exemption will be granted. If granted, the exemption will also confirm the concentration of hydrogen that can be delivered in a live trial. HyDeploy can only go ahead to a live trial in Phase 3 if this safety case is approved by the HSE.
The HSE must be satisfied that the blended gas is ‘as safe as natural gas’ to give permission for it to be distributed through the Keele network. If the HSE is satisfied that it poses no greater risk to safety, and grants permission, then the gas is compliant with the regulations under the terms of the permission. This means it can be supplied to customers for the 12 month trial, as normal gas is today.