Methodological Issues 4621 Choice of method

The IPCC Guidelines outline three methods for calculating CO2 emissions from lead production. The choice of a good practice method depends on national circumstances as shown in the decision tree in Figure 4.15. The Tier 1 method calculates emissions from general emission factors applied to a country's total lead production and is the least accurate. This method is appropriate only when lead production is not a key category. The Tier 2 method uses country specific process material data for both primary and secondary production processes multiplied by the appropriate carbon contents of process materials. The Tier 3 method requires facility-specific measured activity or emissions data.

Figure 4.15

Decision tree for estimation of CO2 emissions from lead production

Decision tree for estimation of CO2 emissions from lead production

Virtualization Flowchart

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

TIER 1 METHOD

The simplest estimation method is to multiply default emission factors by lead production. When the only data available are national lead production statistics, it is good practice to use default emission factors. Equation 4.32 calculates total carbon dioxide emissions from lead production by summing emissions by source and accounting for emissions from secondary feedstock pre-treatment. If it is not possible to differentiate the type of production process, the default emission factor should be used. The default emission factor assumes a that 80 percent of production (including both primary and secondary) is smelted using an Imperial Smelting Furnaces or blast furnaces, while the remaining 20 percent is smelted using the direct smelting method in the Kivcet, Ausmelt, and Queneau-Schumann-Lurgi furnaces. This assumption is consistent with global lead production data (Sjardin, 2003).

Equation 4.32 CO2 EMISSIONS FROM LEAD PRODUCTION

Where:

ECO2 = CO2 emissions from lead production, tonnes DS = quantity of lead produced by Direct Smelting, tonnes

EFds = emission factor for Direct Smelting, tonne CO2/tonne lead product ISF = quantity of lead produced from the Imperial Smelting Furnace, tonnes EFisf = emission factor for Imperial Smelting Furnace, tonne CO2/tonne lead product S = quantity of lead produced from secondary materials, tonnes EFS = emission factor for secondary materials, tonne CO2/tonne lead product The CO2 emission factors used in Equation 4.32 are shown in Table 4.21. TIER 2 METHOD

The Tier 2 method recognizes that there are substantial differences in carbon dioxide emissions for lead production depending on the production methodology and the source of the raw materials, either from secondary sources such as recycled batteries, or, from primary production from ores. Secondary lead sources may be pre-treated to remove impurities resulting in carbon dioxide emissions. Emissions can be calculated using country specific emission factors based on the use of reducing agents, furnace types and other process materials of interest. Factors can be developed based on carbon contents applicable to those materials. Table 4.22 provides carbon contents that can be used to derive country-specific factors. These data may be available from governmental agencies responsible for manufacturing or energy statistics, business or industry trade associations, or individual lead companies. Tier 2 is more accurate than Tier 1 because it takes into account the materials and the variety of furnace types used in the lead sector that contribute to CO2 emissions for a particular country rather than assuming worldwide industry-wide practices.

TIER 3 METHOD

If actual directly measured CO2 emissions data are available from lead facilities, these data can be aggregated and used directly to account for national emissions using the Tier 3 method. Total national emissions will equal the sum of emissions reported from each facility. If facility emissions are not available, emissions should be calculated from plant-specific data for individual reducing agents and other process materials. To achieve a higher level of accuracy than Tier 2, it is good practice to develop emissions estimates at the plant-level because plants can differ substantially in their technology, specifically furnace technology. These data may be available from governmental agencies responsible for manufacturing or energy statistics, or from business or industry trade associations, but is preferably aggregated from data furnished by individual lead facilities.

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