Results of the 2014 Anode Effect Survey - World Aluminium · An anode effect is a process upset...

International Aluminium Institute | www.world-aluminium.org

International Aluminium Institute

Results of the 2014

Anode Effect

Survey Report on the Aluminium Industry’s Global

Perfluorocarbon Gases Emissions Reduction

Programme


Table of Contents Global Aluminium Industry PFC Emissions Reduction Performance 2014 ............................. 4

Industry Trends ..................................................................................................................... 5

2014 Anode Effect Survey ..................................................................................................... 6

Participation Rate .............................................................................................................. 7

Data Requested ................................................................................................................ 8

2014 Survey Results ......................................................................................................... 8

Global Emissions Estimations ..............................................................................................11

Methodology .....................................................................................................................11

Accounting for China ........................................................................................................11

2014 Global Aluminium Industry PFC Emissions ..............................................................12

Uncertainties ........................................................................................................................14

Benchmark Data...................................................................................................................15

Appendix A – Facility Emissions Calculation Methodologies.................................................17

Slope Method ...................................................................................................................17

Overvoltage Method .........................................................................................................18

Global Warming Potentials ...............................................................................................19

Tables

Table 1 – Aluminium smelting technology categories ............................................................ 6

Table 2 - 2014 Anode Effect Survey participation by technology ........................................... 7

Table 3 – Perfluorocarbon emission results from facility data reporting to the 2014 Anode Effect

Survey ........................................................................................................................... 9

Table 4 – Production weighted mean PFC emissions per unit production of reporting entities,

2006-2014 ....................................................................................................................10

Table 5 – Total global 2014 PFC emissions .........................................................................12

Table 6 - Slope and overvoltage coefficients by technology, including uncertainty ...............18


Figures

Figure 1 –Location of primary aluminium production, 1990 & 2006-2014 .............................. 5

Figure 2 – Primary aluminium smelting technology mix, 1990-2014 ...................................... 5

Figure 3 – Median PFC emission rates (as CO2e) of reporting entities, per technology, 2006-

2014 .............................................................................................................................10

Figure 4 – PFC emissions (as CO2e) per tonne of aluminium production, 2006-2014 ..........13

Figure 5 – Absolute PFC emissions (as CO2e) and primary aluminium production, 1990-2014

.....................................................................................................................................13

Figure 6 – PFC emissions (as CO2e per tonne Al) performance of reporters, benchmarked as

cumulative fraction within technologies, 2014 ...............................................................15

Figure 7 - PFC emissions performance of reporters (t CO2e/t Al), benchmarked as cumulative

production within technologies, 1990 & 2014 ................................................................16

4


Global Aluminium Industry PFC Emissions Reduction Performance

2014

Global aluminium industry perfluorocarbon (PFC) emissions intensity (as CO2e per tonne of

production) has been reduced by more than 35% since 2006, almost 90% since 1990.

With primary aluminium production having grown by over 170% over the same period,

absolute emissions of PFCs by the aluminium industry have been reduced from approximate

100 million tonnes of CO2e in 1990 to 34 million tonnes in 2014.

The International Aluminium Institute (IAI) has collected anode effect data directly from primary

aluminium producers for the purposes of calculating sectoral PFC emission inventories for

over a decade, with annual surveys carried out since 2000.

The 2014 Anode Effect Survey generated data from 200 reporting entities (smelters & potlines)

representing 21 million tonnes of primary aluminium production, with emissions from the

remaining 32 million tonnes of global primary aluminium production (the majority in China),

modelled using historic, sampled or technology average data.

This survey report outlines year 2014 data collection and analysis methodologies and global

results. IAI uses global warming potential (GWP) values for perfluorocarbon gases as

published in the IPCC Fourth Assessment Report (2007)

Current and historic PFC emissions data can also be found on the International Aluminium

Institute’s website http://www.world-aluminium.org/statistics/perflurocarbon-pfc-

emissions/#data. As in this report, separate company or country PFC emissions data is not

published, but rather is aggregated by production technology

http://www.world-aluminium.org/statistics/perflurocarbon-pfc-emissions/#data

http://www.world-aluminium.org/statistics/perflurocarbon-pfc-emissions/#data

5


Industry Trends

Growth in primary aluminium production continues to be driven by China and the GCC

countries. In 2014, global primary aluminium production reached 53 million tonnes, to which

that China has contributed over 50%.

Figure 1 –Location of primary aluminium production, 1990 & 2006-2014 (SOURCE: IAI,CNIA,CRU)

Figure 2 – Primary aluminium smelting technology mix, 1990-2014 (SOURCE: IAI,CNIA,CRU)

0

5

10

15

20

25

30

35

40

45

50

55

1990 2006 2007 2008 2009 2010 2011 2012 2013 2014

Pri

mary

Alu

min

ium

Pro

du

cti

on

(millio

n t

on

nes)

China

GCC

Other Asia

Africa

Oceania

South America

CIS

Europe

North America

0

10

20

30

40

50

60

19

90

19

95

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

20

12

20

13

20

14

An

nu

al

Pri

mary

Alu

min

ium

Pro

du

cti

on

(m

illio

n t

on

nes)

HSS

VSS

SWPB

PFPB

CWPB

6


2014 Anode Effect Survey

Perfluorocarbons, or PFCs, are a group of potent greenhouse gases with long atmospheric

lifetimes (in the tens of thousands of years), of which the greatest volume is emitted from

industrial processes. PFCs can be produced in the primary aluminium electrochemical

smelting process, during events referred to as anode effects.

An anode effect is a process upset condition, where an insufficient amount of alumina (Al2O3),

the raw material for primary aluminium production, is dissolved in the electrolyte bath,

contained in the electrolytic cells (or pots) within a smelter reduction line (potline). This causes

the voltage in the pot to be elevated above the normal operating range, resulting in the

emission of gases containing the PFCs tetrafluoromethane (CF4) and hexafluoroethane

(C2F6).

Data on anode effects generated by process monitoring systems allows one to calculate such

emissions. The International Aluminium Institute has collected anode effect data directly from

primary aluminium producers for the purposes of calculating sectoral PFC emission

inventories for over a decade, with annual surveys carried out since 2000.

The IAI Anode Effect Survey requests data from all aluminium smelting facilities around the

world, via IAI member companies (http://www.world-aluminium.org/about/members/), direct

correspondence with non-member producers and regional industry associations. Facilities

are requested, where possible, to report by potline, and to separate data from different

technologies within a single plant. As well as anode effect process data, reporters are also

asked for information that allows for quality control (by comparison against other facilities and

within reporters’ data over time) and for the IAI to take a snapshot and monitor over time the

adoption of anode effect mitigation technologies such as prediction and automatic termination

software. The reporting form and guidelines (PFC001) can be found from the IAI website

(http://www.world-aluminium.org/media/filer_public/2013/01/15/pfc001.pdf).

BROAD TECHNOLOGY

CATEGORY

TECHNOLOGY

CATEGORY

ALUMINA FEED

CONFIGURATION ACRONYM

Prebake

(anodes pre-baked)

Centre Worked Bar broken centre feed CWPB

Point centre feed PFPB

Side Worked Manual side feed SWPB

Søderberg

(anodes baked in-situ)

Vertical Stud Manual side feed

Point feed VSS

Horizontal Stud Manual side feed HSS

Table 1 – Aluminium smelting technology categories

http://www.world-aluminium.org/About+IAI/Links

http://www.world-aluminium.org/media/filer_public/2013/01/15/pfc001.pdf

7


Participation Rate

2014 survey results remain 100% data coverage from SWPB, VSS and HSS technology .On

average, these technologies produce more emissions per tonne of aluminium produced than

the CWPB and PFPB categories. Quite a few potlines using VSS and HSS were closed in

2014.

As the aluminium production in China represents an increasing proportion of the industry and

non-reported data are predominantly from China, the overall reporting rate shown in Figure 5

continues to decrease (40% in 2013). Outside China, about 4 million tonnes of production

(less than 10% of worldwide production), do not report data to the IAI.

TECHNOLOGY

2014 primary

aluminium production

(1,000 tonnes)

2014 production

represented in survey

(1,000 tonnes)

2014

participation rate

by production

CWPB 3,584 1,967 55%

PFPB

(Rest of World) 18,361 15,177 83 %

33% PFPB

(China) 27,517 0 0 %

SWPB 539 539 100 %

VSS 3,024 3,024 100 %

HSS 102 102 100 %

All Technologies

(excluding China) 25,610 20,809 78 %

All Technologies

(Including China) 53127 20,809 39 %

Table 2 - 2014 Anode Effect Survey participation by technology

Note: any inconsistencies due to rounding

The high coverage of the survey data outside China (with respect to both metal production

and emissions) and of the higher emitting technologies, combined with the fact that actual

measurements and secondary information, means that the IAI is able to develop estimates of

PFC emissions from the global aluminium industry, with some degree of accuracy.

8


Data Requested

Annual (1 January – 31 December 2014) data required include:

Annual primary aluminium metal production (MP), the mass of molten metal (in

metric tonnes) tapped from pots in reporting period;

Anode effect frequency (AEF), the average number of anode effects occurring per

cell day over the reporting period;

Anode effect duration (AED), the average time (in minutes) of each anode effect over

the reporting period;

Anode Effect Overvoltage (AEO), the average cell voltage (in millivolts) above the

target operating voltage, when on anode effect, over the reporting period.

Overvoltage is specifically requested from operators employing Rio Tinto Alcan AP-18 or AP-

3x PFPB technologies and SWPB facilities using control technology that records overvoltage

rather than anode effect duration. These anode effect performance data allow for the

calculation, by the Intergovernmental Panel on Climate Change (IPCC) Tier 2 or Tier 3

methodologyF

1F, of facilities’ total annual tetrafluoromethane (CF4) and hexafluoroethane (C2F6)

emissions, and hence tonnes of CO2 equivalent (CO2e) emitted per tonne of aluminium

produced.

It should be noted that the IPCC Tier 1 methodology of multiplying metal production by a

technology-specific coefficient to estimate PFC emissions is not good practice, as the results

are not derived from process data and consequently have a very high uncertainty attached to

them. IAI does not use the Tier 1 methodology in any of its PFC emissions calculations.

2014 Survey Results

Anode effect data was collected from 200 reporting entities (smelters & potlines) representing

21 million tonnes of primary aluminium production. Results are summarised in Error!

Reference source not found. below.

Facilities that have made PFC measurements by which Tier 3 calculation of PFC emissions is

possible account for 46% of the total reported CF4 emissions from survey participants. It

should be noted that Tier 3 calculations typically carry an uncertainty of +/- 15%, with well

controlled systems down to +/- 12%, while uncertainty in Tier 2 calculations can be as high as

+/- 50%."

1 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Primary Aluminium Production,

Chapter 3,Section 4.4, http://www.ipcc-

nggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_4_Ch4_Metal_Industry.pdf.

http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_4_Ch4_Metal_Industry.pdf

http://www.ipcc-nggip.iges.or.jp/public/2006gl/pdf/3_Volume3/V3_4_Ch4_Metal_Industry.pdf

9


Technology IPCC

Tier

No. of

reporting

entities

Reported

production

(kt Al)

Total CF4

emissions

(Gg CF4)

Total C2F6

emissions

(Gg C2F6)

Median CF4

intensity

(kg CF4/

t Al)

Median

C2F6

intensity

(kg C2F6/

t Al)

Mean C2F6:

CF4 weight

ratio

IPCC 4th GWP

Total PFC

emissions2

(kt CO2e)

Median PFC

intensity

(t CO2e/

t Al)

Mean PFC

intensity

(t CO2e/

t Al)

CWPB 2 2 418 0.010 0.001

0.025 0.003 0.13 387 0.22 0.20 3 3 1,548 0.034 0.004

PFPB

2 Slope 63 5,431 0.166 0.020

0.021 0.002 0.12 4,254 0.19 0.28 3 Slope 28 5,607 0.124 0.023

2 OV 18 2,656 0.101 0.012

3 OV 6 1,484 0.082 0.007

SWPB 2 2 43 0.018 0.005

0.303 0.131 0.25 2,668 3.84 4.95 3 3 496 0.237 0.060

VSS 2 60 2,431 0.340 0.018

0.124 0.007 0.14 3,815 1.00 1.26 3 8 593 0.082 0.039

HSS 2 5 66 0.013 0.001

0.188 0.016 0.10 269 1.58 2.65 3 2 36 0.018 0.002

ALL - 200 20,809 1.225 0.192 - - 0.16 11,394 - 0.55

Table 3 – Perfluorocarbon emission results from facility data reporting to the 2014 Anode Effect Survey Note: any inconsistencies due to rounding

2 Carbon dioxide equivalent (CO2e) emissions for survey participants are calculated by multiplying the total tonnes of each PFC component gas by the Global Warming

Potential (GWP) values reported in the IPCC 4th Assessment Report (i.e. 7,390 for CF4 and 12,200 for C2F6).

10


The range of anode effect and PFC emissions performance within technologies is explored

further in the “Benchmark Data” section below. Changes in median emission performance (in

t CO2e/t Al) within technologies between 2006 and 2014 are shown in Figure 5.

Figure 3 – Median PFC emission rates (as CO2e) of reporting entities, per technology, 2006-2014

Reported average (production weighted mean) PFC emissions (as CO2e) per tonne of

production have been reduced by 46% between 2006 and 2014 (CF4 by 49%, C2F6 by 36%).

Reporting

production

(kt Al)

Reporting

rate by

production

CF4 emission

factor

(kg CF4/t Al)

C2F6 emission

factor

(kg C2F6/t Al)

Total PFC

emission

factor

(t CO2e/t Al)

IPCC 4th GWP

2014 20,809 39% 0.059 0.009 0.55

2013 20,135 40% 0.063 0.007 0.55

2012 21,006 44% 0.069 0.008 0.61

2011 22,413 51 % 0.079 0.009 0.68

2010 21,774 53 % 0.071 0.009 0.63

2009 22,184 60 % 0.069 0.008 0.61

2008 24,741 63 % 0.089 0.010 0.78

2007 23,903 63 % 0.106 0.013 0.95

2006 23,177 68 % 0.116 0.014 1.03

Table 4 – Production weighted mean PFC emissions per unit production of reporting entities, 2006-2014

0 1 2 3 4 5 6 7 8 9 10

2006

2007

2008

2009

2010

2011

2012

2013

2014

t CO2e/t Al

SWPB VSS HSS CWPB PFPB

11


Global Emissions Estimations

Methodology

A more realistic picture of the global aluminium industry’s PFC emissions inventory should

include some estimate of the non-reporting industry year on year. In fact, the IAI voluntary

objective is an objective for the industry as a whole, not just IAI membership or reporting

companies and so is based on such a global estimate.

The IAI uses median PFC emissions performance per technology (as shown in Error!

Reference source not found. above) applied to non-reporting production by technology in

order to calculate the global PFC emissions inventory from aluminium production.

Non-reporting aluminium production tonnage data is taken from three sources. The majority

(China 2014 primary aluminium production of 27,517,400 metric tonnes) is reported by the

China Nonferrous Metals Industry Association (CNIA). Around 1.7 million tonnes of production

is from other IAI surveys – primarily IAI Form 100 “Primary Aluminium Production”

(http://www.world-aluminium.org/media/filer_public/2013/01/15/iai_form_100.pdf). Finally,

just under 2 million metric tonnes of production data is kindly provided by the CRU Group

(www.crugroup.com), for facilities where there is no direct IAI data collection.

Accounting for China

Recent (2008-2013) PFC emissions measurements at 27 PFPB facilities in China have yielded

a median emission factor of 0.80 tonnes CO2e per tonne of aluminium produced (CF4 median

0.100 kg/t Al; C2F6:CF4 weight fraction 0.046), compared with a PFPB survey reporter median

performance of 0.20 tonnes CO2e per tonne of aluminium (0.023 kg CF4/t Al; C2F6:CF4

weight ratio = 0.12).

This China-specific value (0.80 t CO2e/t Al) is applied to the 2014 Chinese non-reporting

PFPB cohort, in place of the IAI PFPB survey median, and has also been applied to historical

Chinese non-reporting production, to derive a time series that more accurately reflects

Chinese smelter performance and global emissions than one based on rest-of-world

averages, albeit one that remains static over time.

http://www.world-aluminium.org/media/filer_public/2013/01/15/iai_form_100.pdf

http://www.crugroup.com/

12


2014 Global Aluminium Industry PFC Emissions

Summing the emissions and production data from reporting and non-reporting facilities and

then dividing total global PFC emissions (t CO2e) by total global production (t Al), gives a

production weighted average 2014 PFC emissions performance for the global aluminium

industry of 0.64 tonnes of CO2e per tonne of primary aluminium produced, as outlined in Table

5 – Total global 2014 PFC emissions

Total PFC

emissions

(1,000 t CO2e)

Total aluminium

production

(1,000 tonnes)

PFC emission

factor

(t CO2e/t Al)

IPCC 4th GWP

Reported 11,394 20,809 0.55

Calculated from non-reporters 22,584 31,144 0.73

TOTAL GLOBAL 33,978 53,127 0.64

Table 5 – Total global 2014 PFC emissions

Note: any inconsistencies due to rounding

Global PFC emissions (as CO2e) per tonne of production have been reduced by 32% since

2006, by 87% since 1990 -- on course to meet the IAI voluntary objective of a 50% reduction

by 2020 on a 2006 baseline.

With PFC emissions per tonne cut by almost 90% since 1990 and primary aluminium

production having grown by 172% over the same period, absolute emissions of PFCs by the

aluminium industry have been reduced from approximate 100 million tonnes of CO2e in 1990

to 34 million tonnes in 2014, a fall of 66%.

13


Figure 4 – PFC emissions (as CO2e) per tonne of aluminium production, 2006-2014

Figure 5 – Absolute PFC emissions (as CO2e) and primary aluminium production, 1990-2014

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

PF

C E

mis

sio

ns (

t C

O2

e/t A

l)

0

20

40

60

80

100

120Annual Primary Aluminium Production (Mt Al)

Total Annual PFC Emissions (Mt CO2e)

14


Uncertainties

Understanding sources and magnitude of uncertainty in the calculation of global industry PFC

emissions is important, not only in terms of the current emissions inventory and its relationship

to top-down measurements of PFCs in the atmosphere, but also with respect to quantifying

the industry’s performance over time.

Given that the 2014 data presented above indicates a significant reduction in total PFC

emissions (as CO2e) since 1990, it is necessary to consider the uncertainties inherent in the

1990 baseline number and the 2014 performance number and to quantify the probability that

the reduction has been made.

Potential significant sources of uncertainty include:

the application of average industry IPCC Tier 2 calculation factors,

use of Tier 2 factors for calculating PFC emissions for survey participants where

suitable facility specific measurements are not available, and,

estimate of PFC emissions for producers that do not participate in the anode effect

survey.

Uncertainty arises from the use of IPCC Tier 2 average industry factors due to the uncertainty

in the mean slope and overvoltage coefficients. Additional PFC measurements will reduce

the uncertainty of the mean coefficient values. However, for all technology groups there is

considerable variance in the individual values of slope and overvoltage coefficients, from

which the means are calculated. For this reason, calculations of PFC emissions with Tier 2

coefficients will be more uncertain than calculations made with Tier 3 coefficients, calculated

from PFC measurements made using good measurement practices. Calculations of PFC

emissions for non-reporters is even more uncertain where, due to lack of availability of anode

effect performance, the median emission factors of reporters per technology is applied to non-

reporters.

15


Benchmark Data

The IAI Anode Effect Survey provides respondents with valuable benchmark information,

allowing producers to judge their performance relative to others operating with similar

technology. Calculated PFC emissions benchmark data is presented in this section in the

form of both cumulative probability and cumulative production graphs.

The vertical axes show the cumulative fraction of reporting facilities that perform at or below

the level chosen on the vertical axis. For facilities reporting data from multiple potlines, a data

point is shown for each potline.

To illustrate how the graph in Figure is interpreted consider, for example, the 0.5 point on the

vertical axis, at which the HSS data point is 1.58 t CO2e/t Al. The interpretation is that 50% of

all potlines/facilities reporting HSS anode effect data operate at or below 1.58 t CO2e/t Al. At

1.0 on the vertical axis the HSS point is 7.67 t CO2e/t Al. The interpretation is that all HSS

facilities reported anode effect data that reflected PFC emissions performance at or below

7.67 t CO2e/t Al or, in other words, the maximum value calculated for HSS operators in 2014

was 7.67 t CO2e/t Al.

Figure 6 – PFC emissions (as CO2e per tonne Al) performance of reporters, benchmarked as cumulative

fraction within technologies, 2014

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Cu

mu

lati

ve

Fra

cti

on

of

Re

po

rtin

g E

nti

tie

s

PFC Emission Factor (t CO2e/t Al)

CWPB & PFPB SWPB HSS VSS

Note: SWPB 100th

percentile outliers is at

11.5 t CO2e/t Al.

16


Taking the 1990 reporting cohort and plotting it against 2014 data shows improvement both from existing facilities over this time but also,

importantly, the positive contribution of new (predominantly PFPB) capacity added since 1990.

Figure 7 - PFC emissions performance of reporters (t CO2e/t Al), benchmarked as cumulative production within technologies, 1990 & 2014

0

5

10

15

20

25

30

35

40

45

0 5 10 15 20

PFC

Em

issi

on

s (t

CO

2-e

q/t

on

ne

Al)

Cumulative Aluminium Production of Reporting Facilities (Million tonnes)

PFPB&CWPB

SWPB

HSS

VSS

20141990

17


Appendix A – Facility Emissions Calculation Methodologies

Slope Method

The basic equations for calculation of PFC emission rates from facilities reporting anode effect

frequency and duration are:

𝐸𝐶𝐹4= 𝑆𝐶𝐹4

× (𝐴𝐸𝐹 × 𝐴𝐸𝐷) × 𝑀𝑃

and

𝐸𝐶2𝐹6= 𝐸𝐶𝐹4

× 𝐹𝐶2𝐹6/𝐶𝐹4

where

𝐸𝐶𝐹4= kilograms of 𝐶𝐹4emitted

𝐸𝐶2𝐹6= kilograms of 𝐶2𝐹6emitted

𝑆𝐶𝐹4= slope coefficient for 𝐶𝐹4

𝐹𝐶2𝐹6/𝐶𝐹4= weight fraction of 𝐶2𝐹6 to 𝐶𝐹4

While AEF and AED are reported data, the slope coefficient for CF4 can be either “facility

specific” (IPCC Tier 3 methodology), or “technology specific” (IPCC Tier 2 methodology). The

first of these options, Tier 3, is the more certain method for calculating emissions and involves

use of a slope coefficient (and weight fraction) derived from direct measurement of PFC

emissions at the facility. The Tier 2 method involves the use of slope coefficients that are an

average of measurement data available in 2005 taken from facilities around the world within

technology classes.

18


Table 6 - Slope and overvoltage coefficients by technology, including uncertainty (Source: IPCC, 2006)

Participants in the Anode Effect Survey are asked to report if a facility-specific direct

measurement of PFC emissions had been made and if a Tier 3 slope coefficient and weight

fraction are available for calculating PFC emissions from the smelter. The remainder of the

PFC emissions data are calculated using IPCC Tier 2 methodology with industry average

coefficients.

Overvoltage Method

For smelters that report overvoltage data, the following equations are employed:

𝐸𝐶𝐹4= 𝑂𝑉𝐶 ×

𝐴𝐸𝑂

𝐶𝐸100⁄

× 𝑀𝑃

and

𝐸𝐶2𝐹6= 𝐸𝐶𝐹4

× 𝐹𝐶2𝐹6/𝐶𝐹4

where

𝐸𝐶𝐹4= kilograms of 𝐶𝐹4𝑒𝑚𝑖𝑡𝑡𝑒𝑑

𝐸𝐶2𝐹6= kilograms of 𝐶2𝐹6𝑒𝑚𝑖𝑡𝑡𝑒𝑑

𝑂𝑉𝐶 = overvoltage coefficient for 𝐶𝐹4

𝐶𝐸 = current efficiency, expressed as %

𝐹𝐶2𝐹6/𝐶𝐹4= weight fraction of 𝐶2𝐹6 to 𝐶𝐹4

19


Again, a Tier 3 methodology applies a facility specific overvoltage coefficient and weight

fraction, derived from on site PFC measurements and anode effect data and reported as part

of the Survey return. Tier 2 calculations apply technology specific, average coefficients, which

are outlined in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.

Global Warming Potentials

Carbon dioxide equivalent (CO2e) emissions for survey participants are calculated by

multiplying the total tonnes of each PFC component gas by the Global Warming Potential

(GWP) values reported in the IPCC Fourth Assessment ReportF

3:

𝐸𝐶𝑂2𝑒 = (𝐸𝐶𝐹4× 7390) + (𝐸𝐶2𝐹6

× 12200)

For benchmarking purposes (that is to say, comparing emissions performance between

facilities of the same technology but with different levels of production), total (or “absolute”)

CO2e emissions are divided by relevant aluminium production, to give an emission factor in

tonnes of CO2e per tonne of aluminium produced:

𝐸𝐹𝐶𝑂2𝑒 =𝐸𝐶𝑂2𝑒

𝑀𝑃

3 The latest data published by IPCC in the Fourth Assessment Report reports the CF4 GWP as 7,390

and the C2F6 GWP as 12,200.

Published by:

INTERNATIONAL ALUMINIUM INSTITUTE

10 Charles II Street

London

SW1Y 4AA

United Kingdom

Tel: + 44 (0) 20 7930 0528

Fax: + 44 (0) 20 7321 0183

Email: [email protected]

© International Aluminium Institute

A company limited by guarantee. Registered in London no. 1052007

mailto:[email protected]

Results of the 2014 Anode Effect Survey - World Aluminium · An anode effect is a process upset...

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