Choice of activity data


For the Tier 1 method, inventory compilers need to obtain national primary production data and knowledge of raw material type used in the country. As discussed in Section, these data may not be publicly available and therefore be difficult to obtain, in particular for small-scale (particularly thermal reduction type) production units in developing countries. Approximate national magnesium production data may be available through industry associations such as the International Magnesium Association. For the Tier 2 method, inventory compilers need to collect primary magnesium production data and data on carbonate raw materials from each company/plant. With the Tier 3 method, activity data consists of direct measured and reported emissions.


For the Tier 1 method, it is good practice to disaggregate production data into segments using SF6, if possible, (e.g., primary production, recycling, billet casting, die casting, gravity casting, etc.) and apply available segment-specific emission factors. Where disaggregated data are not available, more aggregated production data, possibly combining output from several different processes, may be used to provide an estimate. In the absence of SF6 consumption data or magnesium production data, the alternative is to collect annual national data on SF6 sales to the magnesium industry. SF6 producers may be able to provide these data directly, or they may be available from national statistics. It is good practice to consider data on consumption by other industries that use SF6 (e.g., electrical equipment) when estimating the share consumed by the magnesium industry.

With the Tier 3 and 2 methods, the activity data are reported SF6 (and secondary gas product) emissions or SF6 consumption totals from each plant. For the Tier 1 method, national- or individual plant- magnesium production data are necessary. Where there is some direct reporting of SF6 use in a segment, it is good practice to assess the share of production represented by the plants that directly report. For the other plants, it is good practice to use production-based estimates of emissions.

HFC-134a, FK 5-1-12 and decomposition products (e.g., PFCs)

With the Tier 3 method, activity data consists of direct measured and reported emissions. No Tier 1 or 2 method guidance is provided and hence, no activity data are necessary.

Carrier gases

It is good practice in inventory reporting that the chosen activity data for carrier gases are analogous to those of the active compound used. I.e., if CO2 is used as carrier gas for SF6, the activity data of CO2 should reflect that of SF6. If CO2 is used as carrier for HFC-134a or FK 5-1-12, CO2 activity data should reflect HFC-134a or FK 5-112 activity data.

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