Gas metrology is fundamental in facilitating the energy transition and assessing climate change mitigating strategies. Corresponding metrological developments can be extremely challenging. For instance, reference materials and standards for reactive gases need to be developed for applications like CCUS, and highly accurate reference measurement methods will be required to comply with the stringent data quality objectives for greenhouse gas monitoring set by the World Meteorological Organization (WMO), as for example for nitrous oxide set as 0.1 nmol/mol in air (0.03 % rel.).
To handle the increasing level of complexity and the stringent accuracy requirements, innovative solutions in gas metrology are called for: The use of artificial intelligence (AI), advanced analytical methods or novel reference gas standards. Optical measurement methods will play an increasingly important role in gas metrology, with two-fold potential: as analytical method and optical standard, e.g., the well-known Standard Reference Photometer for ozone or the optical gas standard for hydrogen chloride.
With both institutes having been exploring the use of optical methods in gas metrology and following a recently signed Memorandum of Understanding signed by VSL and PTB, each one’s individual expertise in reference gas standards and optical methods have been combined to advance gas metrology. This contribution showcases examples from emerging fields in metrology for climate action and environmental monitoring to completed studies where foundations of optical gas metrology were provided jointly in the past. Optical gas standards for reactive gases like hydrogen chloride, purity assessments of reference materials, and new provisions of services to WMO GAW stations. Furthermore, we will outline new applications of optical methods and achievable accuracies, referring to uncertainties down to the sub-permille level. Finally, the applicability of optical gas standards as a complement to reference material-based gas standards, e.g., in combination with low-cost sensor networks, will be addressed.