For HyDeploy it is important to understand the effect of blending hydrogen with natural gas on existing gas management processes, and make sure that risks are as effectively managed as they are today with just natural gas.
A fire or explosion on a gas network can only occur if:-
(a) there is a leak, and
(b) gas reaches the concentration in air required to be flammable or explode, and
(c) if there is a source of ignition.
The existing gas management processes seek to minimise the risk of each of these stages, and HyDeploy builds on these principles.
In Phase 1 of HyDeploy during the gas safety checks, all the pipework in the University buildings will be leak tested. The gas will still have its characteristic smell and the equipment and procedures used for leak detection will be thoroughly tested to ensure they are as effective on the blend as on natural gas. The characteristics of leakages of a blend are being assessed through extensive modelling.
If a leak occurs, the mixture will only burn if it reaches concentration in air. This point is very similar for both natural gas and for the hydrogen blend. Both natural gas and a blend ignite readily at this point, therefore, both the characteristic smell and the leak detectors used by gas specialists are all designed to identify the presence of gas before this concentration is reached. An important part of the HyDeploy programme is to ensure that this continues to be as effective for the blend as for natural gas.
Only if the HSE is satisfied that this risk is safely managed, will permission be granted to proceed to a live trial.