Advances in metrology for energy-containing gases and emerging demands

Metrological services from National Metrology Institutes related to energy gases have been supported by the programme of key comparisons of the Gas Analysis Working Group of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology since its conception in 1993. Most of the key comparisons have been performed on natural gas composition measurement, which is key to the calculation of natural gas properties, thereby facilitating fiscal metering and the trade in natural gas. In the recent years, non-conventional energy gases and natural gas substitutes, such as refinery gas and biogas have been addressed. The paper gives an overview over the achievements in this area from the first key comparison (CCQM-K1) onward and outlines the current challenges to the metrological community. The ongoing energy transition towards renewable energy gases is at the centre of these challenges. The associated emerging challenges primarily concern the measurement of the concentrations of impurities, such as silicon in biomethane and upgraded biogas, carbon monoxide in hydrogen, and many others. The paper presents the first results of the development of measurement standards and methods for impurities in biogas, biomethane and hydrogen and the implications for the programme of key comparisons.