H21 Phase 2 Technical Summary Report

The H21 Phase 2 research will provide vital evidence both towards the hydrogen village trial and potential town scale pilots, and to the Government, which is aiming to make a decision about the use of hydrogen for home heating by 2026.
The key objectives of the H21 Phase 2 NIC project were to further develop the evidence base supporting conversion of the natural gas distribution network to 100% hydrogen. The key principles of H21 NIC Phase 2 were to:
→ Confirm how we can manage and operate the network safely through an appraisal of existing network equipment, procedures, and network modelling tools.
→ Validate network operations on a purpose-built below 7 barg network, as well as an existing, unoccupied, buried network and provide a platform to publicise and demonstrate a hydrogen network in action.
→ Develop a combined distribution network and downstream Quantitative Risk Assessment (QRA) for 100% hydrogen by further developing the work undertaken on the H21 Phase 1 QRA and the Hy4Heat ‘downstream of ECV’ QRA.
→ Continue to understand how consumers could be engaged with ahead of a conversion. This programme was split into four phases detailed below:
→ Phase 2a – Appraisal of Network 0-7 bar Operations
→ Phase 2b – Unoccupied Network Trials
→ Phase 2c – Combined QRA
→ Phase 2d – Social Sciences
The project, with the support of the HSE’s Science & Research Centre (HSE S&RC) and DNV, successfully undertook a programme of work to review the NGN below 7 barg network operating procedures. The project implemented testing and demonstrations on the Phase 2a Microgrid at DNV Spadeadam and Phase 2b Unoccupied Trial site in South Bank on a repurposed NGN network, to provide and demonstrate the supporting evidence for the required changes to procedures. Details of the outputs of the HSE S&RC procedure review and the evidence collected by DNV from the testing and demonstration projects is provided in detail in this technical summary report.
Due to the differences in gas characteristics between hydrogen and natural gas, changes will be required to some of the operational and maintenance procedures, the evidence of which is provided in this report. The Gas Distribution Networks (GDNs) will need to review the findings from this project when implementing the required changes to their operational and maintenance procedures.