Hydrogen injection into natural gas networks offers a pathway to a low-carbon economy while leveraging existing infrastructure, but it presents significant technical and regulatory challenges. Maximum allowable hydrogen fractions differ by country due to safety, supply security, and end-use considerations, requiring gas network operators to accurately monitor hydrogen levels in compliance with national regulations. Pre-normative research identifies key requirements for measurement technologies: sensors must measure up to 30 mol% hydrogen with 0.1 mol% accuracy, respond within one minute, operate up to 100 bar and 55 °C, and support continuous data acquisition. Thousands of sensors will be needed, especially at TSO entry and exit points and DSO pressure-reducing stations, with earlier deployment prioritized for TSOs before 2030.
Currently, gas chromatography (GC) is the only mature technology meeting all requirements, though its high cost is a limitation. Raman spectroscopy could be an alternative if costs decrease, while emerging metal- hydride technologies show promise for high-pressure applications. Lower-TRL technologies like TCD or Speed-of-Sound sensors may become viable with further breakthroughs.
