Leakage rates of hydrogen-methane gas blends under varying pressure conditions

Integration of hydrogen into the existing natural gas infrastructure is considered a potential pathway that can accelerate the incorporation of hydrogen into the energy sector. While blending renewable hydrogen with natural gas offers advantages such as reduced carbon intensity and the ability to utilize existing infrastructure for hydrogen storage and transportation, there are several concerns, including leakage and associated issues. Understanding the behavior of hydrogen blended with natural gas in the existing infrastructure is crucial to ensure safe and efficient integration. In this study, the leakage rates of mixtures of hydrogen and methane at different molar concentrations (5%, 10%, 20%, and 50% hydrogen) through both precision machined orifices and common pipe fitting threads were investigated. The experiments showed that the leakage rates of these mixtures increased as the hydrogen content increased; however, gas chromatography (GC) analysis showed that hydrogen did not leak preferentially at a greater rate than methane. The results indicate that mixing hydrogen with methane can increase the volume of gas leakage under the same pressure conditions. These findings suggest that mixing hydrogen with natural gas may result in increased volumetric flow rate of gas leaks, but hydrogen alone does not leak preferentially to methane.