Hydrogen Blending: Direct Injection Feasibility Study

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.