f H21 Phase 2B: Planned Live Gas Operations

In line with the UK government’s de-carbonisation strategy, Northern Gas Network’s (NGN) H21 project aims to demonstrate the feasibility of converting the existing <7barg gas distribution network to 100% hydrogen. Following progress on Phase 1 of the H21 programme, Phase 2 was proposed to build on the knowledge acquired to provide further quantified safety-based evidence on the suitability of the GB networks to transport 100% hydrogen. Phase 2 consisted of a number of Project Phases. Phase 2b evaluates network operational procedures in use with 100% hydrogen. Conducted on a repurposed part of the natural gas distribution network and identifying which of these are suitable for a 100% hydrogen network and those that may require adjustments. To achieve this, a gas demonstration facility centred around an existing part of the gas network was built at South Bank, Middlesbrough to accommodate operations within low pressure network parameters and typical network components. A Master Test Plan (MTP) for Phase 2 was subsequently developed by NGN in collaboration with the HSE and DNV to address various aspects of existing network procedures and operations including:
♦ Emergency Response and bad practice demonstrations
♦ Finding Leaks
♦ Accessing Leaks
♦ Assessment of repair techniques
♦ Planned live gas operations
♦ Isolation techniques
♦ Commissioning and decommissioning activities
♦ Pressure regulation and maintenance procedures
♦ Pressure and flow validation
Each practical test was derived from one of the above subcategories within the master test plan. This report details the work conducted within the Planned Live Gas Operation remit completed at the NGN H21 testing facility at South Bank. The programme included eight live gas operations undertaken on the buried hydrogen low pressure network within the South Bank test facility, the network contained both metallic and PE mains with different diameters throughout the grid. This allowed operations to be undertaken in conditions mirroring real life as they would be completed out on the network. The objective of these experiments is to prove routine operations that are undertaken on a day-to-day basis on the NG distribution network can be completed on 100% hydrogen networks. This report details the experimental set-up, operation procedures and method statements used in Section 3; the results and main observations in Section 4, followed by interpretation of results and conclusions in Section 5.
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.