Hydrogen in Multi-occupancy Buildings Feasibility Study - Final Report

There is a requirement for gas distribution network (GDN) operators to understand the cost, safety, and practicality of converting network pipelines from Natural Gas to Hydrogen in multi-occupancy buildings (MOBs). Previous work undertaken during project ‘MOBs Work Pack 2 Asset Information Review’ considered the requirements for converting MOBs to Hydrogen, and identified gaps in technical evidence. SGN is leading a feasibility project with some applied testing to address the evidence gaps identified.
This report summarises the work which has been undertaken as part of Work Pack 3 – QRA and Testing. This includes the development of Quantitative Risk Assessments (QRAs) for Hydrogen MOBs conversion and an overall impact review of the conversion of MOBs.
Work Pack 3 included the development of a Quantitative Risk Assessment (QRA) for Hydrogen MOBs conversion which should:
• Easily integrate with wider network QRAs (e.g., GB QRA) to help complete understanding of safety across the entire system,
• Take account of the network and end user parts of the system in the building,
• Provide a record of underlying evidential basis or, where this is lacking, the justified assumptions or simplifications made in reviewing existing evidential basis (e.g., can it be assumed that occupants will react to a Hydrogen leak in the same way as Natural Gas?),
• Provide a quantified assessment of risk either in the form of:
     o Absolute risk
     o Comparative risk
     o ALARP (“as low as reasonably practicable”)
• Obtain agreement from HSE on conclusions of QRA.
Work Pack 3 also included a review of the overall impact of conversion of MOBs considering:
• The cost and practicality of converting the MOB stock
• The safety of Hydrogen in MOBs vs alternatives
• This study could draw on feasibility type studies – i.e., feasibility review of the conversion of a limited number of real MOBs
• Overall recommendation for the suitability of Hydrogen versus alternatives with potential split between different categories of building
• Further recommendations for transition NIA to SIF project:
     o Trials
     o Further confirmatory evidential work
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.