We report a pilot study organized within the Consultative Committee for Amount of Substance (CCQM), in which the ozone reference standards of 23 institutes have been compared to one common reference, the BIPM ozone reference standard, in a series of bilateral comparisons carried out between July 2003 and February 2005. The BIPM, which maintains as its reference standard a standard reference photometer (SRP) developed by the National Institute of Standards and Technology (NIST, United States), served as pilot laboratory. A total of 25 instruments were compared to the common reference standard, either directly (16 comparisons) or via a transfer standard (9 comparisons). The comparisons were made over the ozone mole fraction range 0 nmol/mol to 500 nmol/mol.Two reference methods for measuring ozone mole fractions in synthetic air were compared, thanks to the participation of two institutes maintaining a gas-phase titration system with traceability of measurements to primary gas standards of NO and NO2, while the 23 other instruments were based on UV absorption.In the first instance, each comparison was characterized by the two parameters of a linear equation, as well as their related uncertainties, computed with generalized least-squares regression software. Analysis of these results using the Birge ratio indicated an underestimation of the uncertainties associated with the measurement results of some of the ozone standards, particularly the NIST SRPs.As a final result of the pilot study, the difference from the reference value (BIPM-SRP27 measurement result) and its related uncertainty were calculated for each ozone standard at the two nominal ozone mole fractions of 80 nmol/mol and 420 nmol/mol.Main text. To reach the main text of this paper, click on Final Report.The final report has been peer-reviewed and approved for publication by the CCQM.

At the highest metrological level, natural gas standards are commonly prepared gravimetrically as PSMs (primary standard mixtures). This international key comparison is a repeat of CCQM-K1e-g. The mixtures concerned contain nitrogen, carbon dioxide and the alkanes up to butane. The only difference with CCQM-K1e-g is the addition of iso-butane to the list. The results usually agree within 1% (or better) with the key comparison reference value. For ethane, nitrogen and carbon dioxide, the agreement is within 0.5% (or better), and for methane within 0.1% (or better) of the KCRV.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

At the highest metrological level, natural gas standards are commonly prepared gravimetrically as PSMs (Primary Standard Mixtures). This international key comparison is a repeat of CCQM-K1e-g. The mixtures concerned contain nitrogen, carbon dioxide and the alkanes up to butane. The only difference from CCQM-K1e-g is the addition of iso-butane to the list. The agreement of the results in this key comparison is very good. For all parameters, with a few exceptions, the results agree within 0.5% (or better) with the key comparison reference value. For methane, the results are generally within 0.1% (or better) of the KCRV.Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Energy supply utilities release significant amounts of greenhouse gases (GHGs) into the atmosphere. It is essential to accurately estimate GHG emissions with their uncertainties, for reducing GHG emissions and mitigating climate change. GHG emissions can be calculated by an activity-based method (i.e., fuel consumption) and continuous emission measurement (CEM). In this study, GHG emissions such as CO 2 , CH 4 , and N 2 O are estimated for a heat generation utility, which uses bituminous coal as fuel, by applying both the activity-based method and CEM. CO 2 emissions by the activity-based method are 12-19% less than that by the CEM, while N 2 O and CH 4 emissions by the activity-based method are two orders of magnitude and 60% less than those by the CEM, respectively. Comparing GHG emissions (as CO 2 equivalent) from both methods, total GHG emissions by the activity-based methods are 12-27% lower than that by the CEM, as CO 2 and N 2 O emissions are lower than those by the CEM. Results from uncertainty estimation show that uncertainties in the GHG emissions by the activity-based methods range from 3.4% to about 20%, from 67% to 900%, and from about 70% to about 200% for CO 2 , N 2 O, and CH 4 , respectively, while uncertainties in the GHG emissions by the CEM range from 4% to 4.5%. For the activity-based methods, an uncertainty in the Intergovernmental Panel on Climate Change (IPCC) default net calorific value (NCV) is the major uncertainty contributor to CO 2 emissions, while an uncertainty in the IPCC default emission factor is the major uncertainty contributor to CH 4 and N 2 O emissions. For the CEM, an uncertainty in volumetric flow measurement, especially for the distribution of the volumetric flow rate in a stack, is the major uncertainty contributor to all GHG emissions, while uncertainties in concentration measurements contribute a little to uncertainties in the GHG emissions. Implications: Energy supply utilities contribute a significant portion of the global greenhouse gas (GHG) emissions. It is important to accurately estimate GHG emissions with their uncertainties for reducing GHG emissions and mitigating climate change. GHG emissions can be estimated by an activity-based method and by continuous emission measurement (CEM), yet little study has been done to calculate GHG emissions with uncertainty analysis. This study estimates GHG emissions and their uncertainties, and also identifies major uncertainty contributors for each method.

The key comparison CCQM-K65 was intended to compare the capabilities for the preparation and value assignment of gas standards for methyl and ethyl mercaptans in methane, maintained at the participating national metrological institutes: VNIIM (Russia), KRISS (Korea), VSL (Netherlands) and NPL (United Kingdom). The range of the nominal amount of substance fractions of the comparison gas mixtures was 20 µmol/mol to 30 µmol/mol, which is close to regulatory level (in several countries including Russia) for mercaptans in odorated natural gas. This comparison was proposed at the 12th GAWG meeting in October 2004 and was conducted in 2008.Conclusions are as follows: The results of all laboratories are consistent with the reference values. The observed differences between the reference and reported values are within ±0.9% for methyl mercaptan and ±0.75% for ethyl mercaptan relative to the gravimetric values, and do not exceed the appropriate assigned expanded uncertainties. The prepared mixtures were found to be stable during about a year within the uncertainty of the measurements. The gravimetric values were successfully validated with a dynamic method. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).