The hydrogen economy can be expected to play a significant role in delivering net zero emissions in the UK by 2050. This will require the production of large volumes of hydrogen[AC1]  and the rapid development of a safe and cost-effective H2 pipeline transmission network. In this context, SGN have been investigating the repurposing of the Local Transmission System (LTS) for hydrogen, hydrogen blends and carbon dioxide (CO2). The first phase of this project, “The Future of the LTS”, was a desktop study to understand the feasibility of repurposing the LTS. The study included a case study for repurposing the decommissioned SGN Granton to Grangemouth pipeline. 
In February 2020, SGN held a workshop in Edinburgh to present the findings, identify gaps and develop a roadmap from the first phase. Strathclyde University (Dr Julia Race) and Pipeline Integrity Engineers (PIE) (Dr Jane Haswell and Dr Andrew Cosham[AC2] ) attended this workshop. One of the topics of discussion during the workshop was the known negative effect that hydrogen can have on the ductility and toughness of line pipe steel, (termed “H2 embrittlement”), which can lead to cracking of the steel. Therefore, in order to make a safety justification for the design of new pipelines and/or the reuse of existing pipelines, guidelines are required to close the gaps in knowledge regarding the effects of hydrogen on pipeline materials.

Benefits

This project will expand the understanding of the capabilities of repurposing LTS pipelines for the storage and transport of hydrogen. A review has been done of all GB LTS pipelines and the material chosen for testing is a good representative of the GB network and it is similar to the Granton to Grangemouth pipeline which SGN has earmarked to be the blueprint for repurposing an LTS pipeline for hydrogen.