Effect of hydrogen blending on the accuracy of smart gas meters

The exploitation of green hydrogen blending with natural gas (NG) is expected to contribute in lowering greenhouse gas emissions and fostering the share of renewable energy sources (RES). The NG infrastructure, in fact, can act as a storage facility for green hydrogen produced from excess RES, also providing flexibility to the electric system. However, the unbalance of the networks and the raise of protection issues for consumers may occur as a consequence of the potential decay of the metrological performance of gas meters operating with natural gas and hydrogen blends. In this paper, the authors present the results of an experimental campaign aimed at analysing the effect of hydrogen blending on the accuracy of smart domestic gas meters. Experimental tests were performed in the laboratory using air, natural gas and gas-hydrogen blends up to 23%vol. The results show no criticalities occur for diaphragm and ultrasonic gas meters, regardless of the hydrogen content. On the other hand, thermal mass gas meters show good reliability when hydrogen blends are within 2%vol, whereas for higher hydrogen contents, reliability is demonstrated only when they are equipped with a specific new design routine capable to address the gas quality changes.