[ hydrogen blending ] ensure a smooth and safe transition , updating design records , evaluating fitness for service , and producing operating and maintenance procedures are required . Transmission pipelines pose unique challenges for transporting hydrogen and hydrogen blends compared to natural gas . The impacts of hydrogen increase , and in many cases accelerate , with increasing hydrogen blends and operating pressures . Therefore , it is imperative to do comprehensive tests and trials to ensure the blending operations are functional .
Among key assessments needed to determine pipeline integrity and compatibility for hydrogen blending are :
• Checking for levels of fracture toughness : Hydrogen can diffuse into pipeline steel , reducing toughness and ductility and accelerating fatigue crack growth rate . Monitoring toughness reduction and crack growth rate is critical .
• Pipeline composition : The impacts of hydrogen on steel can vary based on the composition and microstructure . Pipeline workmanship and integrity conditions must be evaluated at the proposed operating condition , as hydrogen can cause embrittlement of many other materials used in transmission systems , including highstrength steel alloys , martensitic steels , and nickel alloys .
• Monitoring hydraulic behavior : Hydrogen has a lower energy density and different thermodynamic properties than natural gas , which changes the fluid ’ s hydraulic behavior as the blend increases . Higher gas velocities in piping pose different stress , vibration , and acoustic induction issues .
• Inspect sealing materials : Hydrogen is a much smaller molecule than methane , meaning leaks from stems , joints , and closures are higher .
One compelling case study is the PG & E Hydrogen to Infinity project in Northern California , which intends to study the feasibility of blending hydrogen from a nearby production facility into full-scale pipeline loop and associated equipment mimicking the existing transmission systems that will need to be used . To do this , in collaboration with industry and other partners , they will conduct tests in three major components :
• A full-scale pipeline loop – built and operated as real-world natural gas transmission pipelines are , but completely standalone so that tests can be run safely ;
• Full-scale destructive-testing facilities – constructing facilities to enable equipment compatibility and leak materials and integrity testing , pushed to the point of destruction to help identify safety limitations ; and
• Laboratory testing – advanced research and testing facility control center and digital infrastructure for monitoring and controlling the pipeline and testing equipment .
Looking forward
As the hydrogen blending industry advances – and with proper preparation , communication with stakeholders and testing of pipeline residence – the number and scale of projects will continue to increase significantly as a vital component of the hydrogen economy , driving decarbonization across many industries , businesses , cities , and communities .
About the author
Kim Domptail is GHD ’ s Future Energy Market Lead in US West . She has 15 years of international experience in waste & energy and currently focuses on hydrogen , renewable natural gas and microgrid developments . Achieving net zero by 2050 is one of the greatest imperatives the world is facing , and Kim is proud of her role at GHD where she connects global multi-disciplinary experts to support a wide range of clients that are providing decarbonization solutions or transitioning to net zero .
Hydrogen Tech World | Issue 15 | April 2024 35