ANNEX IV U.K. Activity-specific monitoring methodologies related to installations (Article 20(2))

8. PFC emissions from production or processing of primary aluminium as listed in Annex I to Directive 2003/87/EC U.K.

B. Determination of PFC emissions U.K.

Calculation Method A — Slope Method U.K.

The operator shall use the following equations for determining PFC emissions:

CF₄ emissions [t] = AEM × (SEF_CF4/1 000) × Pr_Al

C₂F₆ emissions [t] = CF₄ emissions * F_C2F6

Where:

AEM

=

Anode effect minutes/cell-day;

SEF_CF4

=

Slope emission factor [(kg CF₄/t Al produced)/(anode effect minutes/cell-day)]. Where different cell-types are used, different SEF may be applied as appropriate;

Pr_Al

=

Annual production of primary Aluminium [t];

F_C2F6

=

Weight fraction of C₂F₆ (t C₂F₆/t CF₄).

The anode effect minutes per cell-day shall express the frequency of anode effects (number anode effects/cell-day) multiplied by the average duration of anode effects (anode effect minutes/occurrence):

AEM = frequency × average duration

Emission factor

:

The emission factor for CF₄ (slope emission factor, SEF_CF4) expresses the amount [kg] of CF₄ emitted per tonne of aluminium produced per anode effect minute/cell-day. The emission factor (weight fraction F_C2F6) of C₂F₆ expresses the amount [t] of C₂F₆ emitted proportionate to the amount [t] of CF₄ emitted.

Tier 1

:

The operator shall use technology-specific emission factors from Table 1 of this section of Annex IV.

Tier 2

:

The operator shall use installation-specific emission factors for CF₄ and C₂F₆ established through continuous or intermittent field measurements. For the determination of those emission factors the operator shall use the most recent version of the guidance mentioned under tier 3 of section 4.4.2.4 of the 2006 IPCC Guidelines(1). The operator shall determine each emission factor with a maximum uncertainty of ± 15 %.

The operator shall determine the emission factors at least every three years or earlier where necessary due to relevant changes at the installation. Relevant changes shall include a change in the distribution of anode effect duration, or a change in the control algorithm affecting the mix of the types of anode effects or the nature of the anode effect termination routine.

Table 1:

Technology-specific emission factors related to activity data for the slope method

Technology	Emission factor for CF4 (SEFCF4)[(kg CF4/t Al)/(AE-Mins/cell-day)]	Emission factor for C2F6 (FC2F6)[t C2F6/t CF4]
Centre Worked Prebake (CWPB)	0,143	0,121
Vertical Stud Søderberg (VSS)	0,092	0,053

(1)

International Aluminium Institute; The Aluminium Sector Greenhouse Gas Protocol; October 2006; US Environmental Protection Agency and International Aluminium Institute; Protocol for Measurement of Tetrafluoromethane (CF4) and Hexafluoroethane (C2F6) Emissions from Primary Aluminum Production; April 2008.