Choice of method

TIER 1 METHOD

The Tier 1 method should be used (Equation 2.10) where data are not available on glass manufactured by process or the carbonates used in glass manufacturing. Tier 1 applies a default emission factor and cullet ratio to national-level glass production statistics. The uncertainty associated with this method may be considerably higher than the uncertainty associated with the Tier 2 and Tier 3 methods.

Equation 2.10 Tier 1: Emissions based on glass production

Where:

CO2 Emissions = emissions of CO2 from glass production, tonnes Mg = mass of glass produced, tonnes

EF = default emission factor for manufacturing of glass, tonnes CO2/tonne glass CR = cullet ratio for process (either national average or default), fraction TIER 2 METHOD

Tier 2 is a refinement of Tier 1. Instead of collecting national statistics on total glass production, emissions are estimated based on the different glass manufacturing processes undertaken in the country. As discussed below, different glass manufacturing processes (e.g., float glass, container glass, fibre glass, etc) typically use different types and ratios of raw materials. The Tier 2 method applies default emission factors to each glass manufacturing process. The emission estimate must, however, be corrected for the fact that a portion of recycled glass (cullet) may also be supplied to the furnace (Equation 2.11).

Equation 2.11

Tier 2: Emissions based on glass manufacturing process

Where:

CO2 Emissions = emissions of CO2 from glass production, tonnes Mgi = mass of melted glass of type i (e.g., float, container, fibre glass, etc.), tonnes EFi = emission factor for manufacturing of glass of type i, tonnes CO2/tonne glass melted CRi = cullet ratio for manufacturing of glass of type i, fraction TIER 3 METHOD

The Tier 3 methodology is based on accounting for the carbonate input to the glass melting furnace (Equation 2.12).

Equation 2.12 Tier 3: Emissions based on carbonate inputs

Where:

CO2 Emissions = emissions of CO2 from glass production, tonnes

EFi = emissions factor for the particular carbonate i, tonnes CO2/tonne carbonate (see Table 2.1)

Mi = weight or mass of the carbonate i consumed (mined), tonnes

Fj = fraction calcination achieved for the carbonate i, fraction

Where the fraction calcination achieved for the particulate carbonate is not known, it can be assumed that the fraction calcination is equal to 1.00.

Figure 2.3 Decision tree for estimation of CO2 emissions from glass production

Figure 2.3 Decision tree for estimation of CO2 emissions from glass production

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.

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