Net zero and the energy system transition
Hydrogen device trials
In order to support UK ambitions for hydrogen blending and the development of a hydrogen economy National Gas will need to install new gas chromatographs with the capability to measure hydrogen up to 20% in a natural gas blend. At present hydrogen is not measured anywhere on the National Transmission System (NTS) and therefore there are no proven in-use devices and limited experience within the company to allow effective decision making in deploying these assets in the move towards net zero.
In order to make informed decisions ahead of chromatograph fleet upgrade and to allow for a wide selection of reliable device choices when it comes to that upgrade National Gas require the testing of available devices to analyse their performance and thus suitability for NTS installation. This project will employ a trusted testing house to obtain (through loaning) blend-ready chromatographs from suppliers and then to rigorously examine the performance of those devices. These devices could be tested at the testing house’s site or at the instrument vendor’s site.
Net Zero Impact on Wider Network Contents
This project aims to explore the impact of hydrogen blends (in natural gas) 100% hydrogen and carbon dioxide on contaminants (arisings) likely to be found in gas transmission pipelines (e.g. Naturally Occurring Radioactive Materials (NORMs) dusts mill scale welding slag glycols water BTEX methanol heavy metals sulphur compounds pyrophorics as well as rotating machinery lube/seal oils and valve sealants etc).
The project will aim to understand the current composition and characteristics of any contaminants the impact of hydrogen and carbon dioxide on the behaviour/composition/presence of contaminants establish how long methane related contaminants will persist on the network (for repurposed pipelines) the potential for contaminants to cause pipeline gas to go ‘off-spec’ and the implications of contaminant interactions on National Transmission System (NTS) operation/integrity.
Sector Size Assessment
This project will deliver a series of reports and presentations which reflect the need to minimise disruption during any conversion taking into account customer needs and the wider supply chain not just the needs of the GDN.
Carbon Networks Phase 2
The UK Government has identified Carbon Capture Utilisation and Storage (CCUS) as a critical enabler of industrial decarbonisation committing £20 billion to early deployment and targeting 20-30 MtCO₂ stored annually by 2030. Much of the UK’s industrial emissions are geographically concentrated opening the door to targeted CCUS clusters that can deliver outsized impact. GDNs are well positioned to play a meaningful role in this emerging ecosystem.
In Carbon Networks Phase 1 Blunomy assessed the strategic fit between CCUS and the GDN business model. The study identified a range of potential roles including local CO₂ collection participation in transport and storage networks and support for blue hydrogen and CO₂ utilisation initiatives – and it highlighted the importance of early positioning to shape regulatory and commercial pathways.
Phase 2 aims to build on this foundation and move from conceptual framing to actionable insight. Blunomy in the next stage will explore specific industrial opportunities within SGN’s and WWU’s footprint engage with project developers and clusters and outline potential pilot activities. Alongside this the work will assess how CCUS participation aligns with SGN’s broader priorities and the implications for regulatory engagement and investment planning.
Fatigue Rig Destructive Testing
High pressure steel pipelines are essential in enabling a safe natural gas transportation network an overly engineered solution tried and tested over several decades proving the NTS to be a robust nationwide asset. The National Transmission System is used to flow gas every day to keep the lights on and our homes heated by connecting large scale industry cities and towns where the network is dynamic allowing for flexibility and adaptability to various flow demand scenarios. This is done so by utilising over 5000 miles of varying grades and differing sizes of pipelines where the gas can flow build line pack for high energy demand areas and provide a mass energy storage solution.
The NTS is used to limit gas loss manage flow direction facilitate maintenance repair modification testing and commissioning to enable safe and effective start-up and shutdown of our pipelines. We now must further evidence pipeline steel material integrity when subjected to high pressure hydrogen gas this can be done by expanding upon the existing fatigue rig standalone testing at DNV Spadeadam.
Although some pipelines materials that we use today have seen blends and 100% hydrogen within the HYNTS Phase 1 test facility what we have not done is post hydrogen fatigue cycling non destructive testing of materials that have been subject to prolonged high pressure hydrogen. One of the welds that make up the fatigue rig has a known weld defect within it NGT aims to have the welds and the weld defect analysed through various methods of testing such as magnetic particle inspection followed by if necessary standard ultrasonic testing.
In 2022 small scale mechanical characteristic tests were conducted to characterise the mechanical properties of the materials used within the construction of the fatigue rig this testing commenced outputting a standard mechanical property data set the new end of test data post hydrogen exposure will be compared to the original data set from 2022 at the end of fatigue cycling. Testing will establish the effect of trapped hydrogen on ‘standard’ mechanical properties measured To facilitate this DNV will remove all girth welds selected seam welds and fitting welds and store them at low temperature to mitigate loss of hydrogen from within the trap sites..
A technical note will be prepared comparing the results of the weld inspections (internal and external inspections). The note will be used to confirm defect removal for metallographic examination.
A technical report will be prepared summarising the macro and microscopic examinations undertaken confirming defect size (to that reported by UT) and whether the defect was an original feature else created due to the pressure cycle duty of the test vessel and the hydrogen environment.
Understanding the value of remote detectors
The statistical ‘value’ (i.e. risk reduction and cost) of remote hydrogen detectors has been determined through statistical based projects as part of the hydrogen heating programme (HHP). The cost has been shown to outweigh the risk however given hydrogen is not a mature heating solution the cost can be justified in response to risk appetite from key stakeholders such as consumers. This risk appetite is assumed. There is currently no analysis (qualitative or quantitative) into consumers attitudes towards the ‘value’ of remote detectors. This project will begin to explore the perception of risk reduction from remote detectors to be used to compliment the statistical based analysis to paint a fuller picture towards the utilisation and crucially the value of remote detectors.
Welding Residual Stress Measurements and Analysis for Gas Pipelines
This project concerns the research into welding residual stress values and the effect that they have on the overall pipework repurposing assessment route described in relevant hydrogen standards. Currently overly conservative values need to be applied for welding residual stresses in any repurposing assessment. This project aims to build evidence on actual and modelled residual stresses seen within the pipelines industries with a focus on natural gas pipelines. As the welding residual stress is a critical aspect of the fracture mechanics assessment any improvements which can be gained would have an overall positive impact on the assessment results.
Accuracy of electronic volume conversion systems when metering blends of hydrogen and natural gas
This project focuses on ensuring accurate volume conversion within gas metering processes as hydrogen is blended into the natural gas network across Great Britain. Accurate measurement is essential for fair billing and maintaining customer trust during the energy transition. The project will study real world metering installations assess potential errors caused by hydrogen blending and develop practical mitigation strategies. Findings will inform updates to industry guidance (IGEM/GM/5) supporting regulatory compliance and operational integrity.
HyProximity
This project aims to develop a robust evidence-based framework to support the introduction of standardised separation distance tables for 100% hydrogen similar in format and function to those in IGEM/TD/3 for natural gas and hydrogen blends. This will address a gap in current standards for hydrogen. The Institute of Gas Engineers and Managers (IGEM) are providing resource to support the project and to update any necessary standards.
Hybrid Heat Systems (HHS) Acceleration Route
Project will deliver strategic analysis and recommendations to support the accelerated adoption of Hybrid Heat Systems (HHS) in GB. This includes assessing technology options commercial models stakeholder perspectives and system integration pathways. The work will result in actionable insights clear positioning of HHS within the wider decarbonisation strategy.
Hydrogen Blending Implementation Programme Phase 2B
Following the successful completion of Blending Implementation Plan (BIP) Phase 1 (Planning) in 2023 and BIP Phase 2A (Design) in 2025 the gas networks have engaged KPMG to proceed with the next phase of the programme BIP Phase 2B (Delivery).
Running from February 2026 to November 2026 and focusing on Market Frameworks impacts Phase 2B is required to build on the consensus achieved in Phase 2A and close out all implementation areas that require joint-decision making by the networks. These decisions pertain to detailed design of the application window and industry governance. The outcomes of Phase 2B will create a clear and consistent pathway for individual networks to support the application window and connections process alongside addressing common areas of industry governance based on collective decision making to meet timelines of future HAR.
Hydrogen-Enhanced Biomethane for Energy System Resilience
Biomethane from Anaerobic Digestion is currently injected into Gas Distribution Networks as a renewable alternative to fossil-fuel based natural gas.
AD plants currently supply largely constant flows whilst gas demand fluctuates daily and seasonally creating supply-demand imbalances which increase system balancing requirements.
Flexible locally produced biomethane could help GDNs manage system balance by increasing injection during demand peaks or cold spells.
This project will use biomethanisation injecting hydrogen to convert additional CO₂ within digesters to boost biomethane output dynamically supporting network balancing and Net-Zero ambitions.
Operational and regulatory frameworks will also be assessed to enable wider adoption of dynamic injection.
Catalysing Biomethane Growth in the UK
This project constitutes a UK-wide strategic assessment of the policy and regulatory frameworks governing biomethane production and grid injection with the objective of identifying how these frameworks can be updated to unlock growth. The review will examine the current policy landscape support mechanisms and regulatory arrangements affecting biomethane development including uncertainties associated with existing schemes and fragmented governance structures.
Hydrogen Condition and Test Effects (HCATE): NIA project funding
The Hydrogen Condition and Test Effect (HCATE) project will investigate the effect of moisture on fatigue crack growth rate (FCGR) and the influence of loading rate on fracture toughness of API 5L X52 pipeline steel in hydrogen environments. The project will generate experimental data to improve understanding of how environmental conditions influence crack propagation behaviour and fracture resistance in pipeline steels.
Laboratory-scale testing will be conducted on representative pipeline material in air and pressurised gaseous hydrogen environments including hydrogen saturated with water and hydrogen containing trace oxygen. These conditions are intended to simulate environmental conditions that may be present within pipeline systems.
Complementary fracture toughness testing will also be conducted at different loading rates to evaluate the influence of loading conditions on fracture resistance. The results will support the development of improved pipeline integrity assessments and contribute to the evidence base required for the safe repurposing of the UK Local Transmission System (LTS) for hydrogen transport.
Hydrogen Fracture Surfaces Assessment
The LTS Futures project aims to understand how the local transmission system (LTS) could be repurposed from Natural Gas to hydrogen. The project encompasses several elements which will feed into a blueprint methodology for repurposing the LTS to hydrogen. During one of the work elements LTS Futures conducted full-scale testing of pipeline defects and small-bore connections exposed to hydrogen. Testing was conducted until failure to provide information for hydrogen pipeline design standards and operational procedures. This project will undertake further detailed analysis of the fracture surfaces to provide a visual confirmation of hydrogen diffusion into the pipeline microstructure and if this contributed to failure.
Hazardous Areas Impact Mitigation (HAIM) Phase 3
NIA_NGN_346 demonstrated that in a 100% hydrogen conversion scenario hazardous areas of some above ground installations (AGIs) on the network would extend far beyond their current site boundaries. The Hazardous Area Impact Mitigation (HAIM) work programme was set up to investigate these findings and develop potential mitigations. Results highlighted discrepancies between the calculated values from the IGEM/SR/25 hydrogen supplement and empirical test measurements as well as revealed the compound impact of rounding on calculated hazardous zones.
HAIM 3 will propose two methods to reduce the specified zones from AGIs based on the evidence to date:
- Refine the IGEM/SR/25 supplement based on evidence from the HAIM results.
- Use the knowledge gained during the HAIM works to adapt AGI vents and sites to reduce plume sizes and hence exclusion zones. This is independent of any changes to IGEM/SR/25 and can be applied in parallel.
Both methods independently act to reduce the specified zones surrounding vent pipes in AGIs.
Additional evidence gaps around hydrogen/Natural Gas blends up to 20% will be examined by replicating the phase 2 workshop tests for blends. During the project additional opportunities will be sought to collaborate and share knowledge with any third-party studies of large-scale gas releases.
Biomethane HP storage injection
To investigate the potential to use high pressure storage assets to directly inject biomethane.
Network Blending Blueprint
The Technical Blueprint Project forms a critical enabling phase of Cadent’s Hydrogen Blending Implementation Programme. Its purpose is to translate existing high level hydrogen blending evidence into a detailed network specific asset level and operationally deliverable blueprint that defines what is required for the gas network to safely and compliantly accommodate hydrogen blends of up to 20% by volume once regulatory approval is granted.
While previous industry projects have established that hydrogen blending is feasible in principle many technical operational and cost decisions remain at an asset process system and people level. These gaps currently prevent informed investment decisions and cannot be addressed through business‑as‑usual activity. This project addresses that gap by undertaking structured technical validation impact refinement and mitigation definition across Cadent’s network with a particular focus on the North West and East Midlands as pilot regions.
The project will coordinate specialist technical suppliers to validate prior hydrogen impact assessments against the most up‑to‑date safety evidence identify and close remaining evidence gaps and determine clear final mitigation positions for all affected assets and operational activities. Outputs will be consolidated into a single integrated technical blueprint providing a sequenced and costed set of actions required to achieve “blend readiness”. Areas confirmed as having no impact will also be explicitly documented to avoid unnecessary future intervention and cost.
The Technical Blueprint will provide Cadent and wider GB networks with a robust evidence‑based foundation to support future regulatory submissions funding reopeners and implementation planning. Learning generated will be transferable across gas distribution networks supporting a coordinated cost‑effective and safe transition toward hydrogen blending while reducing long‑term consumer risk and avoiding premature or inefficient investment.
Air Ingress in a Live Environment
Using Cartrefi Hydrogen Home as a test case this project will enable remote monitoring of air ingress phenomena within the home. The system will be used to characterise the current behaviour of the house and to investigate generic air ingress dynamics in a representative domestic hydrogen installation.
Project Evergreen
This project will develop understanding of how the GB gas network would operate in a system aligned to Future Energy Scenarios (FES) 2025 scenarios for 2050.