Climate MRV for Africa Phase 2 Development of National GHG ...2017/11/23 · Aluminium Production and Global CO 2 Emissions The smelting of aluminium is an energy intensive process

Climate MRV for Africa – Phase 2

Development of National GHG Inventory

Aluminium Production (IPPU)

Climate MRV for Africa

Project of the European Commission

DG Climate Action

EuropeAid/136245/DH/SER/MULTI

Laura Lahti, Key Expert

January 2017

Lead partner

Essentials of Aluminium: Uses

Packaging

Cars and

Transportation

Powerlines

Construction

Household objects

http://www.sunhomecans.com/blog/uses-of-

aluminum-metal/

http://www.coolcarsandgirls.com/2013/08/metals

-used-in-sports-cars-and-for-what.html

http://www.alupro.org.uk/

http://likesuccess.com/img464919

5

Aluminium Production

Primary aluminium is produced

exclusively by the Hall-Heroult

electrolytic process.

During the production, CO2 and the

PFCs (CF4 and C2F6) are emitted to

the atmosphere.

Source: World Aluminium


Techniques

Different technologies of

electrolytic cells used in

aluminium production:

Centre-Worked Prebake

(CWPB)

Side-Worked Prebake

(SWPB)

Horizontal Stud Søderberg

(HSS)

Vertical Stud Søderberg

(VSS).

http://www.coolcarsandgirls.com/2013/08/metals

-used-in-sports-cars-and-for-what.html

Source: Dakota Classification Company, Ammonia Process

GHG Emissions Sources from Aluminium

Production

2Al2O3 + 3C 4Al + 3CO2

Aluminium Production and Global CO2

Emissions

The smelting of aluminium is an energy intensive process (80% of

smelting GHG emissions are indirect)

The remaining CO2 come from direct emissions (IPPU)

Source: CRU (2012), Indirect CO2 Emissions and the Aluminium Industry in Member States of the EU ETS

Inventory Methods

Emissions Potential for the

Category

Emission factor of 1.6 tonnes of CO2 per tonne of

aluminium for plants using prebaked anodes;

Emission factors of up to 1.6 kg of CF4 (GWP 6,500)

and up to 0.4 kg of C2F6 (GWP 9,200) per tonne of

aluminium for plants using prebaked anodes

• In 2014 PFC emissions ranged from 4.95 t CO2e/ per ton of aluminium for SWPB

smelters to as low as 140 kg CO2 for CWPB technology

1 million tonnes of aluminium produced leads to up to

15,680,000 tCO2e of direct emissions

Ammonia Production Inventory

Methods in Georgia The most recent inventory provided PFC emissions

from aluminium production for 2005.

Emissions of 145 tonnes CF4 and 15 tonnes C2F6

were reported, equivalent to 1,080,500 tonnes of

CO2-equivalent (2.5 % of total IPPU emissions).

Aluminium Production Inventory

Methods in Egypt

Cement (CO2) 40%

Ozone Depleting Substances (ODS Substitutes, HFC's

& PFC's) 37%

Nitric Acid Production, (N2O)

12%

Ammonia not used in Urea (CO2)

5%

Iron and Steel, (CO2)

4%

Aliminium Production, (PFC's)

2%

Lime (CO2) 0%

Aluminium Production Emissions in

Egypt in 2005

90% of aluminium goes

into products with long life

times

Africa produced 143,000

metric tonnes of

aluminium in 2016

(approx 3 % of global

production)

Source: Egypt Third National Communication (2016)

GHG emissions from surveyed industrial sectors

emissions, 2005 in CO2equivalent/year

Decision Tree for CO2 Emissions from


Source: IPCC 2006 Vol. 3, Ch. 4, Fig. 4.11

Tier 1 Method for CO2 emissions

IPCC 2006: Tier 1 Method for CO2

emissions

Source: IPCC 2006 Vol. 3, Ch. 4, Eq. 4.20

To calculate CO2 emissions, the Tier 1 method uses broad

characterizations of the electrolytic cell technology (Prebake or

Soderberg) to generate an estimate of CO2 emissions from aluminium

production.

Tier 1 Method for CO2 Emission Factor

Default emission factors for Prebake and Soderberg technologies are

based on International Aluminium Institute global survey data.

Considering the uncertainty of Tier 1 method, it is considered good

practice to use higher tier methods of CO2 if primary aluminium is

considered a key category.

Source: IPCC 2006 Vol. 3, Ch. 4, Table. 4.10

Tier 2 and 3 Methods for CO2

emissions: Prebake cells

Tier 2 and Tier 3 method for CO2 emissions

for Prebake cells (CWPB and SWPB)


Choice of method depends on data availability. Data specifications for each

method:

Tier 2: Based on default values for some of the components

Tier 3: Requires specific operating facility data for all the components

Tier 2/3 hybrid: when data on ash or sulphur content are not available for

each smelter

Two other sources of CO2 emissions are associated with anode baking

furnaces:

1. Combustion of volatile matter released during the baking operation

2. Combustion of baking furnace packing material (coke).




Two other sources of CO2 emissions are associated with anode baking

furnaces.

1. Combustion of volatile matter released during the baking operation

2. Combustion of baking furnace packing material (coke).




The following parameters are the most significant factors in Eq. 4.21:

Metal production

Net anode consumption for Prebake technology

Other parameters in the equation make minor adjustment for the non-carbon

components of the anode, without significant effects.

Tier Method 2:

o Based on default values (listed in the guidelines)

Tier Method 3:

o Based on the use of specific operating facility data for the minor

components, as well.

o Improves accuracy no more than 5%

Facilities using prebake cells refer to carbon consumed per tonne of aluminium

as ‘net anode or net carbon consumption’, and those using Soderberg cells

refer to it as ‘anode paste consumption’.

Tier 2 and Tier 3 Method for CO2 Emission

Factor for Prebake cells (CWPB and SWPB)

Source: IPCC 2006 Vol. 3, Ch. 4, Table 4.11









Tier 2 and 3 Methods for CO2

emissions: Soderberg cells

Tier 2 and Tier 3 Method for CO2 Emissions

for Soderberg cells (VSS and HSS)

Eco2=CO2 emissions form paste

consumption, tonnes CO2

Ashp = ash content in pitch, wt %

MP= total metal production, tonnes Al Hp = hydrogen content in pitch, wt %

PC= paste consumption, tonnes/tonne Al Sc = sulphur content in calcined coke, wt %

CSM = emissions of cyclohexane soluble

matter, kg/tonne Al

Ashc = ash content in calcined coke, wt %

BC = binder content in paste, wt % CD = carbon in skimmed dust from Soderberg

cells, tonnes C/tonne Al

Sp =sulphur content in pitch, wt % 44/12 = CO2 molecular mass : carbon atomic

mass ration, dimensionless Source: IPCC 2006 Vol. 3, Ch. 4, Eq. 4.24

The following parameters are the most significant factors in the equation:

Metal production

Paste consumption

The other terms make small corrections based on impurities and minor

differences in the carbon content of the paste materials.

Tier Method 2:

o Based on default values listed in the guidelines

Tier Method 3:

o Based on the use of specific operating facility data for the minor

components, as well.

o Improves accuracy no more than 5%


Factor for Soderberg cells (VSS and HSS)



Factor for Soderberg cells (VSS and HSS)

Uncertainty in CO2 Emissions Estimates

Source of uncertainty Range How to mitigate

Tier 1

• Net carbon consumed for Prebake

technologies and paste consumption

for Soderberg cells.

• ±10%

Move from Tier 1

to Tier 2 methods

Tier 2 and Tier 3

• Carbon anode, paste consumption

and aluminium production

• ±2-5%

N/A

PFC emissions

Aluminium Production and Global GHG

Emissions

Source: Cyclope for Aluwatch (2015), Aluminium and GHG Emissions: are producers playing the same game?

Total PFCs

emissions from

Aluminium

production

worldwide in

2014:

Less than

34,000,000 tCO2e

Global PFC emissions and intensity (1998-2014)

The global

primary aluminium

industry was

estimated to be

responsible for

1% of global

GHG emissions

in 2008

PFCs have been

reduced from

approximate 100 million

tonnes of CO2e in 1990

to 35 million tonnes in

2015, a fall of 64%.

Aluminium Production and Global GHG

Emissions

Source: World Aluminium (206), Report on the Aluminium Industry’s Global

Perfluorocarbon Gases Emissions

Source: Dakota Classification Company, Ammonia Process

PFC Emissions Sources from Aluminium

Production

Source: Cyclope for Aluwatch (2015), Aluminium and GHG Emissions: are producers playing the same game?

Decision Tree for PFC Emissions

Source: IPCC 2006 Vol. 3, Ch. 4, Fig. 4.12

Tier Method 1 for PFC emissions

IPCC 2006: Tier 1 Method for PFC

emissions Tier 1 method uses technology-based default emission factors for the four main

production technology types (CWPB, SWPB, VSS and HSS).

It is considered good practice to use Tier 1 method, when PFCs from primary

aluminium is not a key category and when pertinent process data are not

available form operating facilities.


Tier 1 Method for PFC Emission Factor

Tier Method 2 and 3 for PFC

emissions

The mechanism that produces CF4 and C2F6 are similar, such that the two

gases are considered together when estimating PFC emissions.

With an established relationship between anode effect process data and PFC

emissions, process data collected on an on-going basis can be used to

calculate PFC emissions in lieu of direct measurement of PFCs. Choice of

method depends on the process control technology in use:

Recording of anode effect minutes per cell day,

Recording of overvoltage data.

Slope and overvoltage coefficient are based on direct measurements of PFC:

Tier 2 makes use of an average coefficient from measurements at

numerous facilities

Tier 3 is based on measurements at the individual facility

Tier 2 and Tier 3 method for PFC

emissions


emissions


Use Equation 4.26 when anode effect minutes per cell day are

recorded

Use Equation 4.27 when overvoltage data are recorded.


emissions


Use Equation 4.26 when anode effect minutes per cell day are recorded

Use Equation 4.27 when overvoltage data are recorded.


Tier 2 method is based on:

Technology specific slope

Overvoltage coefficients for the applicable reduction cell and process

control technology.

Source: IPCC 2006 Vol. 3, Ch. 4, Table. 4.16

The Tier 3 method is based on a facility specific slope or anode effect

overvoltage PFC coefficient. This coefficient characterizes the

relationship between:

Facility anode effect performance, and

Measured PFC emissions from periodic or continuous

measurements

These must be consistent with established measurement

practices (U.S. EPA and IAI, 2003) and the International

Aluminium Institute GHG Protocol (IAI, 2005a).

Countries can use a combination of Tier 2 and Tier 3 depending on

the type of data available from individual facilities.


Uncertainty in PFC Emissions Estimates

Source of uncertainty Range How to mitigate

Tier 1

• Large variability in anode

effect performance among

operators using similar

production technology

• By factors of 10

depending on the

anode effect

performance

• Move from Tier 1 to

Tier 2 methods

Tier 2 and Tier 3

• Cell technology type on

whether using Tier 3 over Tier

2

• For Tier 3, not making facility

specific PFC measurements

• ±6% CWPB and

±44% HSS

• ±15%

• Use data obtained

from facility

measurements

• Properly establish

PFC

measurements

(USEPA/IAI, 2003)

CO2 PFC

Tier 1 Production statistics available

Use capacity data as a check on production statistics

Tier 2 & Tier 3

All aluminium smelters have to collect data

to support the methods

Utilize anode effect minutes per cell

day or anode effect overvoltage, and

aluminium production data

Soderberg smelters collect anode paste

consumption data

Individual aluminium companies or

industry groups, national

aluminium associations or the

International Aluminium Institute,

should be consulted to ensure that

the data are

available and in a useable format for

inventory estimation

Prebake smelters record baked anode

consumption

Both methodologies use the same

equation for calculation of CO2 emissions,

however, the Tier 3 method uses facility

specific composition data for anode

materials and Tier 2 method uses industry

average anode composition data

Method Activity Data for CO2 and PFC

Recommendation 1: Maintain records of all the necessary activity

data to support calculations of emissions factors.

Recommendation 2: Compare the facility CO2 and PFC emissions

factors per tonne of aluminium with the predicted default values from

the guidelines

Recommendation 3: Use standard measurement methods to

improve the consistency of the resulting data and knowledge of the

statistical properties of the data.

EPA/IAI Protocol for Measurement of CF4 and C2F6 emissions for Primary Aluminum

production

Recommendation 4: Inter-annual changes in emissions of carbon

dioxide per tonne aluminium should not exceed +/-10 percent, due to

the consistency of the underlying processes that produce carbon

dioxide, whereas the inter-annual changes in emissions of PFCs per

tonne of aluminium may change by values of +/- 100 %

QA/QC for Aluminium Emissions

Considerations for

Reporting

Improve transparency by reporting emissions for PFCs from aluminium

production separately from other sources categories

Report CF4 and C2F6 separately on a mass basis

To ensure protection of confidential production and process data, apply

appropriate techniques, including aggregation of data

Develop a consistent time series:

For carbon dioxide emissions, generally feasible since most facilities historically have

measured and recorded anode or paste consumption

For PFC related activity data, anode effect minutes per cell day or overvoltage gives

the best time series results

It is likely that some facilities have limited information on PFC as it only became

relevant in the 1990s

Considerations when extrapolating Tier 3 PFC emission factors to past inventory

periods:

Technology upgrades

Substantial changes in work practices

Changes in the calculation of underlying process data

Quality of the measurements made to establish the Tier 3 coefficients.

Additional helpful information on splicing methods and details regarding constructing a time

series for primary aluminium is available from the International Aluminium Institute (IAI,

2005). Expert advice is also available from the IAI regarding greenhouse gas emissions and

typical industry emissions from aluminium production.

Considerations for

Reporting

Thank you!

Amr Osama Abdel-Aziz, Assen Gasharov, Mike Bess and Laura Lahti

Climate MRV for Africa Phase 2 Development of National GHG ...2017/11/23 · Aluminium Production and Global CO 2 Emissions The smelting of aluminium is an energy intensive process

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