Aluminium PFC

Methodologies relating to perfluorocarbon (PFC) emissions from electrolysis in the aluminium industry are available at the following categories:

• Default PFC methodology - this category provides a calculation methodology for CF₄ and C₂F₆ emissions using default emissions factors. This category represents the Tier 1 approach under the IPCC guidelines.

• Overvoltage PFC methodology - this category provides a calculation methodology for CF₄ and C₂F₆ emissions based on data describing aluminium production and anode effect minutes per cell day. This methodology represents Tier 2 and 3 approaches for PFC emissions under IPCC guidelines.

• Slope PFC methodology - this category provides a calculation methodology for CF₄ and C₂F₆ emissions based on anode effect overvoltage data. This methodology represents Tier 2 and 3 approaches for PFC emissions under IPCC guidelines.

The Slope and Overvoltage methodologies can be used using either of the following cases:

• IPCC Tier 3 method - If direct measurements of CF₄ and C₂F₆ have been made at smelters, potline or smelter specific correlations between PFC emissions and anode effect parameters (AEM or AEO) can be developed.

• IPCC Tier 2 method - If no direct measurements of CF₄ and C₂F₆ have been made at smelters, default industry coefficients depending on the cells technologies are used.

If anode effect process data is unavailable or incomplete the Default sub-category can be used instead, which calculates emissions based on industry typical values.