Learnings

Outcomes

Key objectives included expanding the QRA model to cover various MOB configurations, conducting building surveys, testing the integrity of materials and fittings, as well as assessing ventilation, pressure testing, commissioning, and electrical safety for hydrogen use in MOBs.

The QRA effectively identified risk differentials between hydrogen and natural gas in MOBs of varying storey heights and riser configurations and demonstrated that hydrogen risks, with mitigation measures, can be brought in line with or below those associated with natural gas.

Building surveys gathered data from MOBs with a variety of building heights, riser configurations, gas uses, construction types and ages that were utilised for analysis in other tasks in this phase of work.

Hydrogen flow performance was analysed across surveyed buildings, revealing that most met pressure limits, though some exceeded velocity constraints. This identified feasibility of capacity for hydrogen transport in risers. Further work has been identified to determine the velocity limit in MOBs.

Ventilation needs were assessed in various MOB areas, confirming existing standards are largely adequate and identifying practical constraints for meter relocation. It demonstrated that additional ventilation measures could be feasibly implemented to meet safety targets.

A thorough compatibility assessment using the H21 methodology showed many existing components are compatible with hydrogen, though some legacy materials and sealants failed. Initial integrity testing with hydrogen confirmed the potential for using existing components, with further tests planned for more detailed insights. The work demonstrated a method for evaluating components under hydrogen exposure, helping fill a key evidence gap. Finite Element Analysis proved that compliant laterals retain structural integrity for over 100 years under hydrogen. It determined current IGEM/G/5 limits are acceptable while highlighting areas where additional stress analysis would be necessary. The task confirmed most existing electrical safety standards and equipment clearances remain valid for hydrogen. It also identified where upgrades to IIC-rated equipment may be needed, particularly in poorly ventilated common areas. Fire testing standards for natural gas were shown to be conservative and applicable to hydrogen, supporting continuity in safety protocols. It validated maintaining current test temperatures and leakage criteria for hydrogen transitions. A review of pressure testing procedures confirmed that existing strength and tightness test procedures can be adapted for hydrogen with minor modifications. The study confirmed that current purging techniques are suitable for hydrogen, with some procedural refinements. It highlighted the importance of full access during purging to avoid hazardous unpurged branches. This Phase of the MOBs project established, using the QRA, that existing gas risers can be converted to hydrogen in 99% of cases given appropriate mitigations are applied to the MOB and IGEM/G/5 compliance can be demonstrated.

Lessons Learnt

This is a feasibility study with further research and live trials required to move the deployment of hydrogen in MOBs to the next TRL. The project has produced recommendations that will be addressed in future projects to validate the case for hydrogen in MOBs.