Choice of emission factors tier 1 method

Carbon dioxide emission factors

Table 4.1 provides default emission factors for coke, sinter, pellet, iron, and steel production. The emission factors for the three steelmaking methods are based on expert judgment using typical practice for the different steel production scenarios listed. The default emission factors account for all carbon input into the blast furnace. It is assumed based on the Integrated Pollution Prevention and Control (IPPC) Reference Document on Production of Iron and Steel (European IPPC Bureau, 2001) (referred to in this section as 'IPPC I&S BAT Document') that most of the carbon input to the blast furnace is from coke (60 -90 percent).

The default CO2 emission factor for coke production is derived by averaging plant-specific CO2 emissions data for 11 European coke plants reported in the IPPC I&S BAT Document. Emissions of CO2 are reported in Table 6.2 of the IPPC I&S BAT Document in units of kilograms of CO2 per tonne of liquid steel produced. The CO2 emissions range from 175 to 200 kg CO2 per tonne liquid steel. The conversion factors provided in Table 6.2 of the IPPC Document are 940 kg pig iron per tonne liquid steel and 358 kg coke per tonne pig iron. Based on these conversion factors the average CO2 emissions from the 11 European coke plants is 0.56 tonne CO2 per tonne coke produced.

The CO2 emission factor for sinter plants is derived by averaging plant-specific CO2 emissions data for four European sinter plants reported in the IPPC I&S BAT Document. Emissions of CO2 are reported in Table 4.1 of the IPPC I&S BAT Document in units of kilograms of CO2 per tonne of liquid steel produced. The CO2 emissions range from 205 to 240 kg CO2 per tonne liquid steel. The conversion factors provided in Table 4.1 of the IPPC I&S BAT Document are 940 kg pig iron per tonne liquid steel and 1160 kg sinter per tonne pig iron. Based on these conversion factors the average CO2 emissions from the four European sinter plants is 0.2 kg CO2 per kg sinter produced.

The CO2 emission factor for blast furnace iron making is derived by averaging plant-specific CO2 emissions data for European sinter plants reported in the IPPC I&S BAT Document. The CO2 and CO content of blast furnace gas produced by the iron making process is reported in Tables 7.2 and 7.3 of the IPPC I&S BAT Document in units of kilograms of CO2 per tonne of pig iron produced and kilograms of CO per tonne of pig iron produced. The CO2 content ranges from 400 to 900 kg CO2 per tonne pig iron produced and the CO content ranges from 300 to 700 kg CO per tonne of pig iron produced. Based on the assumption that all of the blast furnace gas burned for energy recovery (and combusted to CO2) within the integrated iron and steel mill and that no blast furnace gas is transferred off site, this corresponds to an emission factor of 1.35 kg CO2 per kg pig iron produced.

Table 4.1

Tier 1 default CO2 emission factors for coke production and iron & steel production

Process

Emission Factor

Source

Sinter Production (tonne CO2 per tonne sinter produced)

0.20

Sinter Production: European IPPC Bureau (2001), Integrated Pollution Prevention and Control (IPPC) Best Available Techniques Reference Document on the Production of Iron and Steel, December 2001, Table 4.1, Page 29. http://eippcb.jrc.es/pages/FActivities.htm

Coke Oven (tonne CO2 per tonne coke produced)

0.56

Coke Production: European IPPC Bureau (2001), Integrated Pollution Prevention and Control (IPPC) Best Available Techniques Reference Document on the Production of Iron and Steel, December 2001, Table 6.2, Page 122. http://eippcb.jrc.es/pages/FActivities.htm

Iron Production (tonne CO2 per tonne pig iron produced)

1.35

Iron Production: European IPPC Bureau (2001), Integrated Pollution Prevention and Control (IPPC) Best Available Techniques Reference Document on the Production of Iron and Steel, December 2001, Tables 7.2 and 7.3. http://eippcb.jrc.es/pages/FActivities.htm

Direct Reduced Iron production (tonne CO2 per tonne DRI produced)

0.70

Direct Reduced Iron Production: European IPPC Bureau (2001), Integrated Pollution Prevention and Control (IPPC) Best Available Techniques Reference Document on the Production of Iron and Steel, December 2001, Table 10.1 Page 322 and Table 10.4 Page 331. http://eippcb.jrc.es/pages/FActivities.htm

Pellet production (tonne CO2 per tonne pellet produced)

0.03

Pellet Production: European IPPC Bureau (2001), Integrated Pollution Prevention and Control (IPPC) Best Available Techniques Reference Document on the Production of Iron and Steel, December 2001, Table 5.1 Page 95. http://eippcb.jrc.es/pages/FActivities.htm

Steelmaking Method

Basic Oxygen Furnace (BOF) (tonne CO2 per tonne of steel produced)

1.46

Steel Production: Consensus of experts and IISI Environmental Performance Indicators 2003 STEEL

(International Iron and Steel Institute, 2004)

Electric Arc Furnace (EAF) (tonne CO2 per tonne of steel produced) **

0.08

Steel Production: Consensus of experts and IISI Environmental Performance Indicators 2003 STEEL

(International Iron and Steel Institute, 2004)

Open Hearth Furnace (OHF) (tonne CO2 per tonne of steel produced)

1.72

Steel Production: Consensus of experts and IISI Environmental Performance Indicators 2003 STEEL (International Iron and Steel Institute, 2004)

Global Average Factor (65% BOF, 30% EAF, 5% OHF)* (tonne CO2 per tonne of steel produced)

1.06

Steel Production: Consensus of experts and IISI Environmental Performance Indicators 2003 STEEL

(International Iron and Steel Institute, 2004)

* Factor based on 2003 international data where BOFs accounted for approximately 63 percent of world steel production and EAFs approximately 33 percent; OHF production accounted for the remaining 4 percent but is declining.

** The emission factor for EAF steelmaking does not include emissions from iron production. The emission factors for BOF and OHF steelmaking do include emissions from blast furnace iron production.

Note that the CO2 emission factor for EAF steelmaking in this table is based on production of steel from scrap metal, and therefore the EAF emission factor does not account for any CO2 emissions from blast furnace iron making. The Tier 1 CO2 emission factor for EAFs in this table is therefore not applicable to EAFs that use pig iron as a raw material.

The emission factor for pellet production is based on the IPPC I&S BAT Document which provides an emission factor range of 15.6 to 31.8 kg CO2 per tonne product. However, the CO2 emission factor for a specific process will depend on the characteristic of the raw materials and fuels used in the process. The emission factor would vary depending upon whether coal, natural gas, or coke oven gas was used as the primary fuel. The 'default' emission factor provided is at the high end of the range, 30 kg CO2 per tonne product, and should be used if the inventory compiler does not know anything about the fuels or raw materials used. If the inventory compiler knows the inputs used, CO2 emissions should be calculated using the Tier 2 method, accounting for the fuel consumption, heating value and carbon content of the fuel.

For the purposes of Tier 1 emission calculations, it is assumed that the default fuel for production of Direct Reduced Iron is natural gas. Natural gas-based processes account for the vast majority of installed direct reduced iron (DRI) production capacity worldwide, with 63 percent of that capacity being the MIDREX process. Fuel consumption for production of direct reduced iron using the MIDREX process is typically 10.5 - 14.5 GJ natural gas/metric tonne solid DRI assuming 100 percent lump iron ore operation. Fuel consumption for production of hot briquetted iron from iron fines was reported to be 12.5 GJ natural gas per tonne of product for the FINMET process and 14 GJ natural gas per tonne of product for the CIRCORED process. The default energy consumption of 12.5 GJ natural gas per tonne of DRI produced and the default carbon content of natural gas of 15.3 kg carbon per GJ natural gas correspond to a CO2 emission factor of 191.3 kg carbon per tonne DRI produced (0.7 tonnes CO2 per tonne DRI produced).

Methane emission factors

Default CH4 emission factors are provided in Table 4.2 below. The Tier 1 CH4 emission factor for coke production is derived by averaging plant-specific CH4 emissions data for 11 European coke plants reported in the IPPC I&S BAT Document. Emissions of CH4 are reported in Table 6.2 and Table 6.3 of the IPPC I&S BAT Document in units of grams of CH4 per tonne of liquid steel produced. The CH4 emissions reported range from 27 to 32 grams CH4 per tonne liquid steel. Based on the conversion factors the average CH4 emissions from the 11 European coke plants is 0.1 grams CH4 per tonne coke produced.

The Tier 1 CH4 emission factor for sinter production is derived by averaging plant-specific CH4 emissions data for European sinter plants reported in the EMEP/CORINAIR Emissions Inventory Guidebook (EEA, 2005) and in other emission inventory reports. Emissions of CH4 are reported in Table 8.2a of the EMEP/CORINAIR Emission Inventory Guidebook for sinter and palletising plants. For sinter plants using coke breeze an emission factor of 50 mg CH4 per MJ was reported and a range of coke input of 38 to 55 kg coke per tonne sinter was reported. This corresponds to an average emission factor of 0.07 kg CH4 per tonne sinter using the default value of 28.2 TJ/Gg coke. An emission factor of 0.05 kg CH4 per tonne sinter was reported for sinter plants operating in Finland. (Pipatti, 2001)

Table 4.2

Tier 1 default CH4 emission factors for coke production and iron & steel production

Process

Emission Factor

Source

Coke Production

0.1 g per tonne of coke produced

Coke Production: European IPPC Bureau (2001), Integrated Pollution Prevention and Control (IPPC) Best Available Techniques Reference Document on the Production of Iron and Steel, December 2001, Table 6.2-3, Page 122. http://eippcb.jrc.es/pages/FActivities.htm

Sinter Production

0.07 kg per tonne of sinter produced

EMEP/CORINAIR Emission Inventory Guidebook (EEA, 2005). Processes With Contact: Sinter and Pelletizing Plants: Sinter and Pelletizing Plants (Except Combustion 030301) Table 8.2a Emission factors for gaseous compounds

DRI Production

1 kg /TJ (on a net calorific basis)

Energy Volume default emission factor for CH4 Emissions from natural gas combustion. [See Table 2.3 of Volume 2, Chapter 2.]

TIER 2 METHOD

The default carbon contents in Table 4.3 should be used if an inventory compiler does not have information on conditions in iron and steel-making facilities and coke production facilities, but has detailed activity data for the process materials and offsite transfers. The Tier 2 method, as described in Equation 4.2 for integrated coke production, Equations 4.9 to 4.11 for iron and steel production and Equation 4.3 for non-integrated coke production includes the major material flows in iron and steel-making and coke production that lead to emissions. Carbon contents in Table 4.3 are based on those provided in Table 1.2 and 1.3 in Volume 2, Chapter 1.

Table 4.3

Tier 2 material-specific carbon contents for iron & steel and coke production (kg C/kg )

Process Materials

Carbon Content

Blast Furnace Gas

0.17

Charcoal*

0.91

Coal1

0.67

Coal Tar

0.62

Coke

0.83

Coke Oven Gas

0.47

Coking Coal

0.73

Direct Reduced Iron (DRI)

0.02

Dolomite

0.13

EAF Carbon Electrodes2

0.82

EAF Charge Carbon3

0.83

Fuel Oil4

0.86

Gas Coke

0.83

Hot Briquetted Iron

0.02

Limestone

0.12

Natural Gas

0.73

Oxygen Steel Furnace Gas

0.35

Petroleum Coke

0.87

Purchased Pig Iron

0.04

Scrap Iron

0.04

Steel

0.01

Source: Default values are consistent with the those provided in Vol 2 and have been calculated with the assumptions below. Complete references for carbon content data are included in Table 1.2 and 1.3 in Volume 2, Chapter 1.

Notes:

1 Assumed other bituminous coal

2 Assumed 80 percent petroleum coke and 20 percent coal tar

3 Assumed coke oven coke

4 Assumed gas/diesel fuel

* The amount of CO2 emissions from charcoal can be calculated by using this carbon content value, but it should be reported as zero in national greenhouse gas inventories. (See Section 1.2 of Volume 1.)

TIER 3 METHODS

The Tier 3 method is based on aggregated plant-specific emission estimates or the application of the Tier 2 equations at a plant specific level. The inventory compiler should ensure that each facility has documented the emission factors and carbon contents used, and that these emission factors are indicative of the processes and materials used at the facility. The Tier 3 method requires carbon contents and production/consumption mass rates for all of the process materials and off-site transfers such as those listed in Table 4.3. While Table 4.3 provides default carbon contents, it is good practice under Tier 3 to adjust these values to reflect variations at the plant level from default values represented in the table. The default factors listed in Table 4.3 are only appropriate for the Tier 3 method if plant-specific information indicates that they correspond to actual conditions. It is anticipated that for the Tier 3 method the plant-specific data would include both carbon content data and production/consumption mass rate data, and that therefore the default values in Table 4.3 would not be applied to the Tier 3 method in most instances.

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