Life Cycle Assessment of gas and future hydrogen pipeline infrastructure in Germany: a comparative study of relevant materials and installation techniques

• - A harmonized ISO 14040/44-compliant LCA framework is developed for gas and future hydrogen pipeline infrastructure under German network conditions. • - Pipeline material choice strongly influences life cycle impacts, with polyethylene pipelines showing substantially lower global warming potential (GWP) than steel pipelines across all technically applicable diameter ranges. • - Installation location is a key driver of construction-related emissions, as open-trench installation in urban areas causes significantly higher impacts due to excavation and surface restoration. • - For small nominal diameters, fugitive methane emissions dominate the total GWP, whereas for medium and large diameters production-related emissions prevail. Gas pipeline networks are a key component of today’s energy infrastructure and are expected to play a crucial role in future hydrogen supply systems. However, the environmental impacts associated with different pipeline materials and installation techniques are still insufficiently quantified in life cycle studies. This study applies a life cycle assessment (LCA) in accordance with ISO 14040 and ISO 14044 to evaluate the environmental impacts of common pipeline materials used in the German gas network, including welded and seamless steel as well as polyethylene materials (PE and PE-X). Three installation techniques are analyzed: open-trench (OT) installation with sand bedding and two trenchless methods, horizontal directional drilling and impact moling. The results show that steel pipelines exhibit the highest environmental burden, particularly in the production phase, while polyethylene pipelines generally achieve lower global warming potential (GWP) where technically applicable. In the construction phase, especially in urban areas, open-trench installation results in substantially higher impacts than trenchless methods due to excavation and surface restoration. For small nominal diameters, fugitive methane emissions dominate the total GWP, whereas for medium and large diameters production-related emissions prevail. The quantified impacts of pipeline production, construction, and end-of-life phases are independent of the transported gas and are therefore transferable to both natural gas and hydrogen infrastructures. However, due to the limited availability of reliable emission factors for hydrogen leakage, the use-phase assessment is currently restricted to natural gas systems. Overall, the findings provide a consistent basis for sustainable network planning and support the transition towards hydrogen-ready gas infrastructures with reduced life cycle impacts.