The transition from methane to hydrogen in the NTS presents several challenges and considerations. Hydrogen’s lower ignition energy, wider flammability range, and lower density compared to methane necessitate a careful reassessment of current purge practices. Implementing an optimal purging method becomes crucial to economically remove methane from the network during the transition. Defining acceptance criteria and determining the endpoints purge for hydrogen are essential steps to ensure safety and efficiency. Additionally, addressing the skills gap and training requirements is imperative for personnel involved in handling hydrogen, emphasising the need for specialised training programs to facilitate a smooth and secure transition.
Benefits
An understanding of how hydrogen will impact current purging tools, equipment and practices
- Identify changes required to adapt existing policies, safety processes, standards, and procedures to accommodate hydrogen
- Inform NGT future training program
- Inform Project Union conversion strategy
- Set the scene for further demonstration work to confirm the ability to safely purge hydrogen-containing equipment.
Learnings
Outcomes
Value tracking Data Point Data Point Definition
Maturity TRL2-3 Concept stage for purging procedures for transitioning from methane to hydrogen
Opportunity 100% or multiple asset class The project can be applied to Pipeline, Branched pipework, Stub/dead end pipework, Above Ground Installations AGIs
Deployment costs - Estimates of unit costs provided to inform deployment costs, based upon extent of NGT usage. Case study example provided
Innovation cost £ 239,693.33 The cost includes desktop-based work and site visits.
Financial Savings - Case by case dependent
Safety - Detailed the impact of hydrogen on NTS purging practices E.g. flammability mixtures in the pipeline NTS safety case evidence to HSE.
Environment - GHG considerations of hydrogen relative to methane leakage /emissions
Compliance Support compliance Guidelines & procedures reviewed
Skills & Competencies Individuals Skills gap analysis and training requirements detailed
Future proof Supports business strategy The project will help enable hydrogen in the NTS and support the energy transition.
The net benefits delivered so far are identification of a feasible and safe purging approach for a hydrogen transmission network, examples of providers for novel technology and a plan to address remaining gaps.
With forecast benefits to be delivered in other projects and follow on work, including detailed design and completion of the proposed test plan, to validate and verify the findings and refine the proposed approach. Gaps are further addressed in other ongoing projects, such as NGT Hydrogen Flares Design for NTS
Lessons Learnt
Throughout the project, the DNV team recognised the merits of early engagement with the NGT steering group to obtain their expectations from the related portions of scope. Future early stakeholder engagement would bear fruit in aligning on scope and streamline comments and report revisions.
The project successfully reviewed current purging practices and recommended updates to technical aspects, such as rider sizes and the required minimum purging velocities. It also provided insights into how nitrogen can be sourced and used efficiently. The research conducted was highly effective in informing the proposed approach and identifying gaps in best practices and current academic literature, which should be addressed in future projects.
