Hydrogen in natural gas infrastructure: techno-economic assessment of repurposing existing grids

Renewable hydrogen (H2) blending and H2 transport in existing natural gas (NG) grids are expected to support energy decarbonisation while reducing delivery costs. However, several regulatory (like ATEX Directives) and technological issues concerning the existing infrastructure still need to be addressed. Among the technological barriers, measurement performance is paramount in NG transmission and distribution networks for fiscal, process, monitoring, and safety purposes. Measuring device categories include gas meters, pressure and temperature transmitters, gas chromatographs, trace water humidity sensors, and leak detectors. Researchers involved in the projects "Novel methods of testing for measurement of natural gas and hydrogen mixtures" (THOTH2) and the PNRR “Network for Energy Sustainable Transition” (NEST) are collaborating to identify H2 limits and thresholds for State-of-the-Art (SoA) measuring devices through experimental tests. The paper presents actual data about the devices installed in the Italian NG grids, allowing the definition of the current SoA. The analysis helps estimate the effort and costs necessary to adapt the existing gas network by replacing devices unsuitable for measuring hydrogen and natural gas (H2NG) mixtures. For this reason, the effect of different hydrogen thresholds related to the maintenance of the measurement performance is also presented.