Opportunities and Challenges in Repurposing Canadian Natural Gas Transmission Pipelines for Hydrogen Service – A Regulatory, Standards, and Technical Exploration

Abstract In decarbonizing Canada’s energy systems, utilizing hydrogen as a low-carbon fuel is growing in interest, and repurposing in-service natural gas transmission pipelines to transport large volumes of hydrogen can be a key solution. Existing intraprovincial natural gas transmission pipelines, such as those in Alberta, can be potential candidates for conversion into hydrogen service in Canada due to factors like steel grades used, pipe hoop stresses, and year of construction. However, all pipelines intended for conversion into hydrogen service must undergo an engineering assessment as outlined in the CSA Z662 to ensure the integrity of the pipeline system and safe operations. While challenges for such conversion exist, discussed in this study, such as high pipe hoop stresses in long-distance interprovincial natural gas transmission pipelines, high specified minimum yield strength, and unavailability of required pipe data, when mitigated, the engineering assessment may determine the pipelines are fit-for-service for hydrogen. This applies not only to line pipe but also to other existing components within the pipeline system that will be exposed to hydrogen, such as gas compressors, meters, fittings, valves, and flanges.