Future Energy Networks

This project aims to assess and enhance the hydrogen readiness of ball valves within the (NTS) by conducting maintenance strategy evaluation with material performance analysis. It involves reviewing current valve operations, diagnostics, and OEM maintenance guidance, alongside a literature review of commonly used valve materials to understand their behaviour under hydrogen exposure. The project valve performance testing and finite element analysis of existing valve designs to evaluate structural integrity. Findings from these activities will provide actionable recommendations for updating NGT’s valves maintenance strategies, diagnostic tools, and design standards to support safe and efficient hydrogen service deployment

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.

This Network Innovation Allowance (NIA) project investigated dew point management in hydrogen/natural gas blends, pure hydrogen and carbon dioxide transmission pipelines. In the National Transmission System (NTS), which is currently a natural gas network, the purity of the gas is carefully controlled via the network entry specification. Trace components, such as water, nitrogen oxides, sulphur containing compounds, oxygen and carbon dioxide have strict limits on their allowable levels in the network. This is done in part to ensure the gas delivered to end users meets the requirements of the customer, but also to protect transport and storage systems. Purity specifications are being developed for hydrogen, its blends with natural gas, and for carbon dioxide (CO₂). This project focused specifically on the water content within these gases, in what concentrations it is likely to be acceptable, the conditions at which it may condense in the network, its interactions with other trace components and contaminants and the potential detrimental effect on the network.

Limiting moisture content and ensuring gas dryness is important for several reasons:

• Safety & Efficiency: Hydrogen’s efficiency as a fuel can be compromised by moisture. Water in hydrogen can affect the combustion process, leading to a reduced efficiency for applications like gas turbines.
• Corrosion: If dew points aren’t controlled effectively, liquid can drop out of the gas phase, and this moisture can cause corrosion in pipelines and hydrogen embrittlement. For CO₂ pipelines this moisture can react to produce carbonic acid which can further corrode the pipelines.

The outcomes of the project should provide a clearer insight and strategy on how to effectively manage hydrogen and carbon dryness within the NTS, ensuring that the gas remains within the required specifications for current and future demands.

The project was split into three work packages (WP):

1. WP1 focused on hydrogen and its blends, initially reviewing the equations of state (EoS) that model the dew point temperature at varying water content and hydrogen/methane blend ratios. The impact on the network of liquid water formation in hydrogen was examined, including the interaction with other trace components such as CO₂ and H₂S, in particular the effect on welds and pipeline defects. Finally, a summary of international standards for hydrogen purity highlighted the likely water content limits that could be expected by hydrogen users and thus provided by producers.

2. WP2 focused on CO₂, its phase behaviour and the effect impurities have on this behaviour using the most appropriate equations of state. The detrimental effect of CO₂ and liquid water contained within it on pipelines, fittings and other parts of the network was reviewed.

3. WP3 focused on how the water content specifications could be managed on the network, from the point of view of monitoring and controlling water dew point in the gases. The water content expected from various production techniques were reviewed and a high-level costing for the dehydration process for both CO₂ and hydrogen was made.

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.

This project has been initiated to assess the technical and commercial feasibility of direct hydrogen injection into the gas distribution network at 5% and 20% by volume. It supports the broader Market Frameworks appraisal by providing the evidence needed to evaluate whether both System Entry Models, direct injection and pre-blending are feasible under varying network conditions.

The need for this study was identified through the Hydrogen Blending Implementation Plan, which outlined two technical approaches for hydrogen connections: injecting hydrogen directly into the network or pre-blending it before entry, each with distinct technical and commercial implications. While National Gas has assessed both models for the transmission network, a gap analysis revealed that these findings are not directly transferable to the distribution network.

Evidence for pre-blending was previously completed as part of HyDeploy and the Hydrogen Blending Functional Specification project. It was shown that this approach provides more controlled mixing but may require more complex infrastructure, leading to higher costs for the producer. Although it is assumed Direct Injection may be achievable at lower cost, there are multiple key technical challenges associated with the technique such as the potential for inadequate hydrogen mixing, which could result in non-compliant gas, safety concerns including material integrity and operational constraints e.g. GSMR exclusion zones.

Through literature review, CFD modelling, engineering assessments, and commercial analysis, the study will evaluate the technical and safety, performance, risks, and cost implications of direct injection across a range of scenarios and configurations.

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.

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.

The key subject of HIRSA stage 2 projects is to understand if using hydrogen in the gas network will result in an increased likelihood of ignition from static discharge generated by particulates in flowing gas. Building on stage 2A, stage 2B will provide further experimental testing aimed at determining the absolute difference in electrostatic charge generated, identify whether any external factors impact one gas more than the other, and to control the factors affecting generation of the charge. The outputs of this work should provide the industry with a better understanding of the potential change in ignition risk when switching from Natural Gas to hydrogen and will also highlight relevant mitigations to manage this risk.

This project investigates how hydrogen affects the integrity of welded joints (seam welds and girth welds) in the UK National Transmission System (NTS) pipelines, as part of plans to repurpose existing natural gas infrastructure for hydrogen transport.

Specifically, Work Package 4 integrates results from metallurgical characterisation, historical weld procedures, and fracture toughness testing conducted in high-pressure hydrogen. The study examines pipeline steels of different grades and vintages (including X46, X52, X60, X65 and X80), focusing on weld metal and heat-affected zones (HAZ), which are known to be the most vulnerable regions.

The report combines:

• Detailed metallography and hardness mapping of real NTS welds,
• Post-test fractographic analysis of specimens tested in hydrogen,
• Interpretation of fracture toughness data,
• An overall assessment of risks and uncertainties associated with hydrogen service,
• Recommendations to support safe decision-making for hydrogen repurposing.

This project is looking to address uncertainties surrounding LTS pipeline materials by investigating the effect of the oxide layer on hydrogen permeation rate for steel pipelines. This project will also investigate the formation of an oxide layer inside the pipe at different temperatures, as well as how the microstructure of the pipeline steel and condition of the oxide layer affect permeation for different grades of steel. It is critical this relation is better understood as these uncertainties are currently hindering our ability to fully and accurately assess the repurposing of the LTS. The outcomes of this project have the potential to increase cost-savings and improve confidence in the existing network to carry hydrogen, including blends.