Choice of method

Methods are classified according the extent of plant-level data that are available. The Tier 1 method is based on default values and national statistics. Tier 2 is based on plant-level data on production and use of CaC2 in acetylene production for welding applications. The Tier 3 method is based on plant-level data on petroleum coke input (including the carbon content factor (CCF) and carbon oxidation factor (COF) if available; alternatively, country specific Energy Sector values may be used), use of CaC2 in acetylene production for welding applications, and plant-level emission factors where relevant.

Both Tier 2 and Tier 3 are based on plant-level activity data. The choice of method to estimate emissions of CO2 and CH4 depends on national circumstances as shown in Figure 3.5.

CO2 AND CH4 FROM CARBIDE PRODUCTION

Tier 1 method

Emissions from carbide production can be estimated from activity data (AD) on petroleum coke consumption or carbide production, calcium carbide used in the production of acetylene used in welding applications, and default emission factors. Where AD on petroleum coke consumption are used the CCF and COF of the petroleum coke can be obtained from Volume 2, Chapter 1 and the result must be multiplied by 44/12 to convert C to CO2. The basic equation for estimating emissions is:

Equation 3.11 Emissions from carbide production

Where:

ECO2 = emissions of CO2, tonnes

AD = activity data on petroleum coke consumption or carbide production, tonnes raw material used or tonnes carbide produced

EF = CO2 emission factor. There are two options as follows:

When carbide production is used as activity data, EF should be average CO2 emissions per unit of output for carbide production, tonnes CO2/tonne carbide production.

When petroleum coke consumption is used as activity data, EF should be CCF (carbon content factor) multiplied by COF (carbon oxidation factor) multiplied by 44/12 and adjusted to account for the C contained in the product, tonnes CO2/tonne material used

Adjustment factor for SiC = 0.35 ^ Emission factor = 0.65 • CCF • COF • 44/12;

Adjustment factor for CaC2 = 0.67 ^ Emission factor = 0.33 • CCF • COF • 44/12.

Equation 3.11 can also be used to estimate CH4 emissions, where EF is the appropriate emission factor for CH4.

Estimation of emissions from CaC2 needs to include emissions of CO2 indirectly attributable to CaC2 that is used in acetylene production. Equation 3.11 can be applied where AD is the amount of CaC2 used and EF is the emission factor associated with this use. Under the Tier 1 method it is good practice to assume that all CaC2 used in acetylene production gives rise to CO2 emissions.

Tier 2 method

The Tier 2 method uses plant-level data on production of carbide and the amount of C contained in the product. For CaC2, data on the use of CaC2 for the production of acetylene used in welding applications is also required. Emissions from production and use can be estimated with Equation 3.11 using default emission factors. Where acetylene is produced from CaC2 at another location and the quantity of CaC2 used for this purpose is not known, it is good practice to document this fact.

Tier 3 method

The Tier 3 method requires plant-level data on the petroleum coke input along with the CCF and COF if available; alternatively, country specific Energy Sector values for CCF and COF may be used. Plant-level data on the amount of C contained in the product are also required.

In the case of CaC2, data on the use of CaC2 for the production of acetylene used in welding applications are required, as are plant-level emission factors. Where acetylene is produced from CaC2 at another location and the quantity of CaC2 used for this purpose is not known, it is good practice to document this fact. In addition, plant-level emission factors for CH4 need to be collected. Equation 3.11 can be applied to estimate emissions for each plant and total national emissions are the sum of these estimates.

Production data are not used in the calculation but should be collected for reporting purposes. Where acetylene production data cannot be disaggregated by use, national inventory compilers using the Tier 3 method are encouraged to account for any emissions at the point where they arise; for example, emissions from acetylene use in welding applications should be accounted for at the point of use of acetylene using a country specific emission factor. A similar approach should be followed for other uses of acetylene.

Figure 3.5 Decision tree for estimation of CO2 and CH4 emissions from carbide production

Figure 3.5 Decision tree for estimation of CO2 and CH4 emissions from carbide production

Note:

1. "Input data" means raw material consumption data.

2. 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. "Input data" means raw material consumption data.

2. 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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