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New facility for accurate CO2 emissions monitoring

Carbon dioxide (CO2) is the greenhouse gas with the largest contribution to global warming. New initiatives to measure emissions and assess the impact of mitigation policies foresee an increase in the number of in situ monitoring sites, and consequently an increased requirement for CO2 in air calibration standards. A newly developed facility at the BIPM Headquarters will allow National Metrology Institutes around the world to demonstrate consistency of their standards and enable uniformity in emission measurements and calculations.

The facility, described in the Metrologia paper, is based on pressure, volume and temperature measurements of CO2 in air and cryogenically extracted CO2. Use of the facility enables the determination and comparison of amount fraction (concentration) values with those of gas cylinder standards. It can operate over a wide range of CO2 concentrations, from those found in background “clean” air to urban sites. The facility was developed by scientists at the BIPM Headquarters together with visiting scientists from the NIST (USA) and RISE (Sweden).

The system has been tested and validated using a selection of gas standards from laboratories that have demonstrated their expertise in the international comparison CCQM-K120 (2016), including NIST, NPL, NIM, VSL, LNE and the World Meteorological Organization (WMO) Central Calibration Laboratory, NOAA-GML (CCQM-P225 report). The new CO2 facility will be the basis of new on-demand comparison services offered by the BIPM Headquarters starting in 2024 (BIPM.QM-K2) and the planned CO2 in air scale standard comparison (BIPM.QM-K5).