What default carbon dioxide does the Intergovernmental Panel on Climate Change use per tonne of steel, and why is the electric arc furnace figure so low?

The Intergovernmental Panel on Climate Change (IPCC) 2006 Tier 1 gives carbon dioxide (CO2) per tonne of steel of 1.46 for the basic oxygen furnace, 1.72 for open hearth and 0.08 for the electric arc furnace, which counts steel from scrap only. A world mix of 65%, 30% and 5% gives 1.06.

Tier 1 factors, tonnes of CO2 per tonne of steel

• Basic oxygen furnace: 1.46. This includes emissions from blast furnace iron production.
• Open hearth furnace: 1.72. Also includes blast furnace iron production.
• Electric arc furnace: 0.08. This does not include emissions from iron production.
• Global average: 1.06, for 65% basic oxygen, 30% electric arc and 5% open hearth (0.65 x 1.46 + 0.30 x 0.08 + 0.05 x 1.72).

Why the electric arc figure is so low, and when it does not apply

The guide bases the electric arc number on steel made from scrap metal. It says the factor is therefore not applicable to electric arc furnaces that use pig iron as a raw material. In a majority of scrap-charged furnaces, it notes, CO2 is mainly from the carbon electrodes. Grid power is a separate Scope 2 line from your bills and is not in these factors.

The guide says some specialty steel is made in electric induction furnaces, where the charge is 100 percent scrap and there are no carbon electrodes, and that there are no appreciable CO2 or methane (CH4) emissions from this steelmaking process. The table has no line for rolling and finishing.

Other defaults in the same table

• Sinter: 0.20 tonnes of CO2 per tonne of sinter.
• Iron production: 1.35 per tonne of pig iron.
• Direct reduced iron: 0.70 per tonne. The guide says the default assumes natural gas as the fuel, so a coal-fired sponge iron kiln should use its own coal tonnes and carbon content.
• Pellets: 0.03 per tonne, the high end of a 15.6 to 31.8 kilogram range.
• Coke oven: 0.56 per tonne of coke.

30,000 tonnes of steel a year under three factors (example output)

• Scrap-based electric arc furnace: 30,000 x 0.08 = 2,400 tonnes of CO2
• World average mix: 30,000 x 1.06 = 31,800 tonnes
• Basic oxygen furnace: 30,000 x 1.46 = 43,800 tonnes

Output is an example number. Picking the wrong route's factor changes the answer by a factor of 10 or more.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the electricity and fuel a mill uses are on file month by month. The route you run, and what is charged into the furnace, decides which default applies.

• Free calculators
• Coal-based sponge iron CO2 per tonne
• Pig iron and sponge iron under CBAM
• Electric arc and induction furnace in one plant, CBAM

Sources: IPCC 2006 Guidelines, Volume 3 chapter 4: Metal Industry Emissions, section 4.2 (Table 4.1)

Last reviewed 2026-11-04. Factors are from the 2006 IPCC Guidelines, which cite 2001 to 2004 industry sources. For the Carbon Border Adjustment Mechanism (CBAM) or a verified figure, plant data replaces them.