Commission Implementing Regulation (EU) 2018/2066Show full title

B. Determination of PFC emissions U.K.

PFC emissions shall be calculated from the emissions measurable in a duct or stack (‘point source emissions’) as well as fugitive emissions using the collection efficiency of the duct:

PFC emissions (total) = PFC emissions (duct) / collection efficiency

The collection efficiency shall be measured when the installation-specific emission factors are determined. For its determination the most recent version of the guidance mentioned under Tier 3 of section 4.4.2.4 of the 2006 IPCC Guidelines shall be used.

The operator shall calculate emissions of CF₄ and C₂F₆ emitted through a duct or stack using one of the following methods:

(a)

Method A where the anode effect minutes per cell-day are recorded;

(b)

Method B where the anode effect overvoltage is recorded.

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 emission factor shall also take into account emissions related to non-anode effects. 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

Calculation Method B – Overvoltage Method: U.K.

Where the anode effect overvoltage is measured, the operator shall use the following equations for the determination of PFC emissions:

• CF₄ emissions [t] = OVC × (AEO/CE) × Pr_Al × 0,001

• C₂F₆ emissions [t] = CF₄ emissions × F_CF2F6

Where:

OVC

=

Overvoltage coefficient (‘emission factor’) expressed as kg CF₄ per tonne of aluminium produced per mV overvoltage;

AEO

=

Anode effect overvoltage per cell [mV] determined as the integral of (time × voltage above the target voltage) divided by the time (duration) of data collection;

CE

=

Average current efficiency of aluminium production [%];

Pr_Al

=

Annual production of primary Aluminium [t];

F_CF2F6

=

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

The term AEO/CE (Anode effect overvoltage / current efficiency) expresses the time-integrated average anode effect overvoltage [mV overvoltage] per average current efficiency [%].

Emission factor: The emission factor for CF₄ (‘overvoltage coefficient’ OVC) shall express the amount [kg] of CF₄ emitted per tonne of aluminium produced per millivolt overvoltage [mV]. The emission factor of C₂F₆ (weight fraction F_C2F6) shall express the amount [t] of C₂F₆ emitted proportionate to the amount [t] of CF₄ emitted.

Tier 1:: The operator shall apply technology-specific emission factors from Table 2 of this section of Annex IV.

Tier 2: The operator shall use installation-specific emission factors for CF₄ [(kg CF₄ / t Al ) / (mV)] and C₂F₆ [t C₂F₆/ t CF₄] 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. The operator shall determine the emission factors with a maximum uncertainty of ± 15 % each.

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 2

Technology-specific emission factors related to overvoltage activity data.

Technology	Emission factor for CF4[(kg CF4/t Al) / mV]	Emission factor for C2F6[t C2F6/ t CF4]
Centre Worked Prebake (CWPB)	1,16	0,121
Vertical Stud Søderberg (VSS)	N.A.	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.