Decarbonisation of heat by repurposing the UK’s local transmission pipeline system

UK carbon emissions commitments will entail moving away from natural gas for heat. Hydrogen has been proposed as the most practical energy vector capable of delivering low-carbon energy at the scale required.

Repurposing the UK's local transmission system (LTS) of underground pipelines for either hydrogen or carbon dioxide transport requires a robust scientific assessment to ensure that all critical technical, operational and safety challenges have been identified and addressed.

How is HSE helping?

HSE scientists and engineers in partnership with SGN carried out a feasibility study to assess the potential for transporting hydrogen, hydrogen-natural gas blends, or carbon dioxide in sections of the UK's LTS.

Expertise in fluid dynamics, materials science and risk assessment was used to determine where modifications may be required in existing pipeline standards to accommodate the different gas types.

In the case of hydrogen transport, the effects of potential changes in mechanical properties of the steel pipelines on integrity and lifetime were evaluated. Case studies on sections of the LTS pipeline were then used to demonstrate approaches that would be required for safe repurposing for the two gases.

What did we learn?

The project identified the gaps to be addressed to ensure safe pipeline repurposing, covering materials performance, inspection, maintenance, repair, risk assessment, land use planning, procedures and standards. These were presented and evaluated at the LTS workshop organised by SGN in 2020, with attendees from across the industry.

The required activities to move towards pipeline repurposing for hydrogen are now being progressed by a cross-industry IGEM (Institute of Gas Engineers and Managers)-led group to allow the gas networks to decarbonise.

HSE, (2021). Sixth Annual Science Review, pp.51-52.