Gas Transmission and Metering (GT&M) are committed to reducing emissions from the operation of the National Transmission System (NTS) and eliminating emissions by 2050. A key technology in this transition is hydrogen as an alternative for carbon fuels in heat, transport, and industrial uses. The NTS currently provides a resilient supply to homes, businesses and industry, and GT&M aim to provide the same capability for hydrogen and hydrogen blends. Natural gas is currently stored within the NTS as linepack which can be utilised during periods of peak energy demand. The energy content of hydrogen is a third of that of methane, which will impact the energy content of linepack. The project will aim to investigate the impact of hydrogen and hydrogen blends on linepack and assess potential solutions to manage linepack in the future.
Benefits
The project will help to identify challenges and opportunities associated with linepack in the energy transition and gain knowledge on potential solutions for further consideration. This will help to inform the hydrogen strategy for NTS.
Learnings
Outcomes
This project has quantified the loss of linepack energy from the NTS when blending hydrogen and for 100% hydrogen, relating to expected blending and Project Union (100% hydrogen). It was previously known that hydrogen has a lower energy density than natural gas, however the actual linepack reduction has now been quantified. Additionally, the project has conducted an assessment of hydrogen storage projects and forecasts and determined how these could support hydrogen linepack in the future. Finally, the project assessed relevant gas transmission regulations and licenses, such as the Gas Transporters License, to determine the applicability to hydrogen transport and any changes we may need to be implemented.
The overall conclusions from the analysis and research undertaken in Work Packages 1 and 2 are:
- Between 2013 and 2018 the NTS contained between 4146 GWhr and 3313 GWhr2 of linepack, therefore applying percentage reductions for 20% and 100% H2 concentrations from Work Package 1 would result in ranges of 3432 – 2743 GWhr and 1099 – 878 GWhr respectively. Therefore, a maximum shortfall of 3268 GWhr.
- Based on the expected demand and production, conversion of existing facilities to hydrogen (i.e., current salt caverns 3 TWh and the depleted hydrocarbon field at Rough 10 TWh) would allow the anticipated storage capacity requirements of 3.4 TWh for 2030 increasing to 9.8 TWh by 2035 to be met. These could satisfy the shortfall in linepack.
Value tracking
Data Point Data Point Definition
Maturity TRL2-3 The project was an impact assessment for hydrogen and linepack. Potential storage solutions were investigated but no concepts were proposed and further work would be required to develop concepts for linepack supplementation and trials/demonstrations towards deployment of solutions.
Opportunity 100% single asset class The project covers the whole NTS but focuses on the gas stored in pipelines
Deployment costs - The project has not developed a solution for deployment.
Innovation cost £195,280 This cost includes model development and modelling scenarios, hydrogen storage technology review, proposal for changes to linepack management including measurement requirements and calculations.
Financial Saving - The project was an impact assessment and technology search and has not resulted in financial savings.
Safety - The project was an impact assessment and technology search and has not resulted in safety improvements.
Environment - The project was an impact assessment and technology search and has not resulted in environmental benefits.
Compliance Supports compliance The project has provided an early indication of linepack requirements for hydrogen, which will affect NGT’s obligations to meet energy demand for customers across the UK.
Skills & Competencies Departmental The project outputs have fed into various teams across NGT including GNCC, SCADA, modelling and Project Union.
Future proof Supports business strategy The GNCC is a critical element for operating the gas network today and will be critical in the safe operation of hydrogen networks in the future.
Lessons Learnt
Technical learnings
· The loss of linepack has been determined for various hydrogen blends and 100% hydrogen. Alongside this, the pressures and velocities were also modelled. As expected, linepack decreases as hydrogen concentration increases in the network. Gas velocity increases with increasing hydrogen, in some cases this is greater than the current allowable velocity on the network. Reassessment of the maximum velocities may be required for hydrogen otherwise gas velocity should be managed accordingly. The impact of limited gas velocity on network management should be investigated.
· Hydrogen storage will be key to supporting hydrogen linepack in the future. Based on the conversion of existing storage facilities to hydrogen, the hydrogen storage requirements could be met. However, more work is required to understand the potential locations of hydrogen storage in the future and how these may integrate with the NTS.
· Relevant codes and standards for natural gas transmission were assessed for hydrogen applicability. It was found that standards such as the Gas Act, Pressure Systems Safety Regulations and Pressure Safety Regulations are not specific to natural gas, however GSMR and the Uniform Network Code will require updating for hydrogen.
· It is expected that more frequent gas measurement will be required and at more locations, however it was not possible to quantify this during this project and has been recommended as further work.
Project delivery learnings
· The original proposal was dependent on the availability of NGT’s internal modelling software. It became apparent early in the project that it would not be possible to share this model with an external supplier, therefore an early change in approach was required. In future projects, there should be more clear expectations set from each stakeholder through more effective communications.
· The change in approach meant the supplier’s internal software was used to carry out the research. Whilst this does not have the extensive capabilities of NGT’s internal model, its simplicity meant scenarios were quicker to run and more scenarios were investigated as a result. For projects which are conducting initial research, this could be a more suitable approach to take followed by refined modelling using NGT internal software.
· A variety of stakeholders were involved with this project from across the lead network, however it was not initially clear who the stakeholders were at the start of the project and what the requirements were throughout. In future projects, there should be a clear stakeholder roadmap to define stakeholders, roles and requirements, and reason for involvement.
