# Commission Regulation (EU) No 601/2012 of 21 June 2012 on the monitoring and reporting of greenhouse gas emissions pursuant to Directive 2003/87/EC of the European Parliament and of the Council (Text with EEA relevance) (repealed), Division Calculation Method B —: Overvoltage Method

Extent: E+W+S+N.I.

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) × PrAl × 0,001
C2F6 emissions [t] = CF4 emissions × FC2F6
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 [%];
PrAl Annual production of primary Aluminium [t];
FC2F6 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 FC2F6) 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

---
Source: https://www.legislation.gov.uk/eur/2012/601/annex/IV/division/8/division/B/division/2 (the official version)
Page: https://openlegislation.uk/eu-regulation-2012-601/annex-IV/division-8/division-B/division-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.