‘ANNEX XXIV

Activity-specific guidelines for the production or processing of primary aluminium as listed in Annex I to Directive 2003/87/EC

1. BOUNDARIES AND COMPLETENESS

The activity-specific guidelines in this Annex shall be applied for emissions from installations for the production or processing of primary aluminium as listed in Annex I to Directive 2003/87/EC.

This Annex includes guidelines for monitoring emissions from the production of electrodes for primary aluminium smelting, which is also applicable for stand-alone plants for the production of such electrodes.

2. DETERMINATION OF GREENHOUSE GAS EMISSIONS

In installations for the production or processing of primary aluminium emission sources and source streams for greenhouse gas emissions include:

— fuels for the production of heat or steam,

— anode production (CO2),

— reduction of Al2O3 during electrolysis (CO2) which is related to electrode consumption,

— use of soda ash or other carbonates for waste gas scrubbing (CO2),

— anode effects (PFCs) including fugitive emissions of PFCs.

2.1. CALCULATION OF CO2 EMISSIONS

2.1.1. COMBUSTION EMISSIONS

Emissions from combustion of fuels, including flue gas scrubbing, shall be monitored and reported in accordance with Annex II, unless they are included in a mass balance pursuant to Section 2.1.2.

2.1.2. MASS BALANCE

Process emissions from anode production and consumption shall be calculated by using a mass-balance approach. The mass-balance approach shall consider all carbon in inputs, stocks, products and other exports from the mixing, forming, baking and recycling of anodes as well as from the electrode consumption in electrolysis. Where pre-baked anodes are used, either separate mass balances for production and consumption may be applied, or one common mass balance taking into account both production and consumption of electrodes. In the case of Søderberg cells, the operator shall use one common mass balance. The mass balance shall determine the level of emissions of greenhouse gases over the reporting period, using the following equation independently of whether a common mass balance or separate mass balances are used:

CO2 emissions [t CO2] = (input – products – export – stock changes) * conversion factor CO2/C

With:

— input [t C]: all carbon entering the boundaries of the mass balance, e.g. pitch, coke, packing coke or purchased anodes,

— products [t C]: all carbon in products and materials, including by-products and waste, leaving the boundaries of the mass balance, e.g. sold anodes,

— export [t C]: carbon exported from the boundaries of the mass balance, e.g. discharged to sewer, deposited into landfill or through losses. Export does not include the release of greenhouse gases into the atmosphere,

— stock changes [t C]: stock increases of carbon within the boundaries of the mass balance.

The calculation shall then be as follows:

CO2 emissions [t CO2] = (Σ (activity datainput * carbon contentinput) – Σ (activity dataproducts * carbon contentproducts) – Σ (activity dataexport * carbon contentexport) – Σ (activity datastock changes * carbon contentstock changes)) * 3,664

With:

(a) activity data

The operator shall analyse and report the mass flows into and from the installation and respective stock changes for all relevant fuels and materials (e.g. pitch, coke or packing coke) separately. Where the carbon content of a mass flow is usually related to energy content (fuels), the operator may determine and use the carbon content related to the energy content [t C/TJ] of the respective mass flow for the calculation of the mass balance.

Tier 1

Activity data over the reporting period are determined with a maximum uncertainty of less than ± 7,5 %.

Tier 2

Activity data over the reporting period are determined with a maximum uncertainty of less than ± 5 %.

Tier 3

Activity data over the reporting period are determined with a maximum uncertainty of less than ± 2,5 %.

Tier 4

Activity data over the reporting period are determined with a maximum uncertainty of less than ± 1,5 %.

(b) carbon content

Tier 1

The carbon content of input or output streams is derived from reference emission factors for fuels or materials named in Section 11 of Annex I or in other activity-specific Annexes to these Guidelines. The carbon content is derived as follows:

C content [t/t or TJ] = Emission factor [t CO2/t or TJ]/3,664 [t CO2/t C]

Tier 2

The operator applies country-specific carbon content for the respective fuel or material as reported by the respective Member State in its latest national inventory submitted to the Secretariat of the United Nations Framework Convention on Climate Change.

Tier 3

The carbon content of input or output stream shall be derived following the provisions of Section 13 of Annex I in respect to representative sampling of fuels, products and by-products, the determination of their carbon contents and biomass fraction.

The carbon content can be derived from direct analysis as well as from indirect analysis, i.e. by subtracting the measured content of known constituents (such as sulphur, hydrogen and ash) from the total amount, as appropriate and subject to the approval of the competent authority.

2.2. MEASUREMENT OF CO2 EMISSIONS

The measurement guidelines contained in Annexes I and XII shall be applied.

3. DETERMINATION OF PFC EMISSIONS

PFC-Emissions from primary aluminium production shall include CF4 and C2F6 emissions expressed as CO2-equivalents:

PFC emissions [t CO2(e)] = CF4-emissions [t CO2(e)] + C2F6-emissions [t CO2(e)]

Carbon dioxide equivalents (t CO2(e)) shall be calculated using Global Warming Potential values provided in the Intergovernmental Panel on Climate Change’s Second Assessment Report (1995 IPCC GWP value). These are:

GWPCF4 = 6 500 t CO2(e)/t CF4

GWPC2F6 = 9 200 t CO2(e)/t C2F6

Total PFC emissions are calculated from the emissions which are measurable in a duct or stack (‘point source emissions’) plus the fugitive emissions using the collection efficiency of the duct:

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

The collection efficiency is 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.

Emissions of CF4 and C2F6 emitted through a duct or stack shall be calculated by one of the following two approaches, depending on the control technologies used. Calculation method A is used where the anode effect minutes per cell-day are recorded, calculation method B shall be used where the anode effect overvoltage is recorded.

Calculation Method A – Slope Method

Where the anode effect minutes per cell-day are measured, the following equations shall be used for determining PFC emissions:

CF4 emissions [t CO2(e)] = AEM × (SEFCF4 /1 000) × PrAl × GWPCF4

C2F6-emissions [t CO2(e)] = CF4 emissions * FC2F6 * GWPC2F6

With:

AEM … Anode effect minutes/cell-day

SEFCF4 … (1) Slope emission factor [(kg CF4/t Al produced)/(anode effect minutes/cell-day)]

PrAl … Annual production of primary Aluminium [t]

FC2F6 … Weight fraction of C2F6 (t C2F6/t CF4)

With

Activity data

(a) Primary Aluminium production

Tier 1

The primary aluminium production over the reporting period is determined with a maximum uncertainty of less than ± 2,5 %.

Tier 2

The primary aluminium production over the reporting period is determined with a maximum uncertainty of less than ± 1,5 %.

(b) Anode effect minutes (AEM)

The Anode effect minutes per cell-day expresses the frequency of anode effects [number of anode effects/cell-day] multiplied by the average duration of anode effects [anode effect minutes/occurrence]:

AEM = frequency × average duration

Tier 1

Frequency and average duration of anode effects over the reporting period are determined with a maximum uncertainty of less than ± 2,5 %.

Tier 2

Frequency and average duration of anode effects over the reporting period are determined with a maximum uncertainty of less than ± 1,5 %.

Emission factor

The emission factor for CF4 (slope emission factor SEFCF4 ) expresses the amount [kg] of CF4 emitted per ton of aluminium produced per anode effect minute/cell-day. The emission factor (weight fraction FC2F6 ) of C2F6 expresses the amount [t] of C2F6 emitted as proportionate to the amount [t] of CF4 emitted.

Tier 1

Technology specific emission factors from Table 1 are used.

Table 1

Technology specific emission factors related to the slope method

Technology Emission Factor for CF4 (SEFCF4 ) [(kg CF4/t Al)/(AE-Minutes/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

Tier 2

Installation-specific emission factors for CF4 and C2F6 established through continuous or intermittent field measurements are used. For the determination of these emission factors the most recent version of the guidance mentioned under Tier 3 of Section 4.4.2.4 of the 2006 IPCC Guidelines (2) shall be used. The emission factors are to be determined with a maximum uncertainty of ± 15 % each.

The emission factors shall be established at least every 3 years or earlier if necessary due to relevant changes at the installation. Relevant changes include a change in the distribution of anode effect duration, or a change in the control algorithm affecting the mix of types of anode effects or the nature of the anode effect termination routine.

Calculation Method B – Overvoltage Method

Where the anode effect overvoltage is measured, the following equations shall be used for determining PFC emissions:

CF4 emissions [t CO2(e)] = OVC × (AEO/CE) × PrAl × GWPCF4 × 0,001

C2F6 emissions [t CO2-eq] = CF4 emissions × FC2F6 × GWPC2F6

with

OVC … Overvoltage coefficient (‘emission factor’) expressed as kg CF4 per tonne 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)

Activity data

(a) Primary Aluminium Production

Tier 1

The primary aluminium production over the reporting period is determined with a maximum uncertainty of less than ± 2,5 %.

Tier 2

The primary aluminium production over the reporting period is determined with a maximum uncertainty of less than ± 1,5 %.

(b) Anode effect overvoltage

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

Tier 1

Anode effect overvoltage as well as current efficiency over the reporting period are each determined with a maximum uncertainty of less than ± 2,5 %.

Tier 2

Anode effect overvoltage as well as current efficiency over the reporting period are each determined with a maximum uncertainty of less than ± 1,5 %.

Emission factor

The emission factor for CF4 (‘overvoltage coefficient’ OVC) expresses the amount [kg] of CF4 emitted per t aluminium produced per millivolt overvoltage [mV]. The emission factor of C2F6 (weight fraction FC2F6 ) expresses the amount [t] of C2F6 emitted as proportionate to the amount [t] of CF4 emitted.

Tier 1

Technology specific emission factors as laid down under Table 2 are used:

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

Tier 2

Installation-specific emission factors for CF4 [(kg CF4/t Al)/mV] and C2F6 [t C2F6/t CF4] established through continuous or intermittent field measurements are used. For the determination of these emission factors the most recent version of the guidance mentioned under Tier 3 of Section 4.4.2.4 of the 2006 IPCC Guidelines (2) shall be used. The emission factors are to be determined with a maximum uncertainty of ± 15 % each.

The emission factors shall be established at least every 3 years or earlier if necessary due to relevant changes at the installation. Relevant changes include a change in the distribution of anode effect duration or a change in the control algorithm affecting the mix of types of anode effects or the nature of the anode effect termination routine.