Hydrogen in natural gas grids: prospects and recommendations about gas flow meters

To inject green hydrogen (H 2 ) into the existing natural gas (NG) infrastructure is one way to decarbonize the European energy system. However, asset readiness is necessary to be successful. Preliminary analysis and experimental results about the compatibility of hydrogen and natural gas mixtures (H2NG) with the actual gas grids make the scientific community confident about the feasibility. Nevertheless, specific technical questions need more research. A significant topic of debate is the impact of H2NG mixtures on the performance of state-of-the-art fiscal measuring devices, which are essential for accurate billing. Identifying and addressing any potential degradation in their metrological performance due to H2NG is critical for decision-making. However, the literature lacks data about the gas meters' technologies currently installed in the NG grids, such as a comprehensive overview of their readiness at different concentrations while data are fragmented among different sources. This paper addresses these gaps by analyzing the main characteristics and categorizing more than 20,000 gas meters installed in THOTH2 project partners’ grids and by summarizing the performance of traditional technologies with H2NG mixtures and pure H2 based on literature review, operators experience and manufacturers knowledge. Based on these insights, recommendations are given to stakeholders on overcoming the identified barriers to facilitate a smooth transition. • H 2 blending and pure H 2 transport in gas grids enables large-scale, long-distance transport with minimal investment. • Gas meters are installed along the network for fiscal and process purposes. • Different gas meter technologies are installed in gas transmission and distribution grids. • Preliminary conclusions on metrological performances and H 2 limits and tolerances are available for each technology. • ATEX (ATmospheres EXplodibles) certification poses a significant legal challenge for hydrogen-natural gas blends.