Blast Furnace Gas
Reviewed by Afonso Firmo, Co-Founder & Director · Updated 7 July 2026
Blast furnace gas has a Scope 1 emission factor of 234.05 kg CO₂-e/GJ under NGA Factors 2025 — the highest of any gaseous fuel. Worked examples inside.
Emission Factor Value
234.05 kg CO₂-e/GJ
Try it with your own numbers
Estimated emissions
—
Blast furnace gas combustion is reported under Scope 1 at 234.05 kg CO₂-e/GJ (NGA Factors 2025, Table 5). Cubic metres are converted at an energy content of 0.004 GJ/m³.
Official Source & Citation
This emission factor is sourced from the Australian National Greenhouse Accounts Factors 2025 , Table 5 — Gaseous fuels including liquefied natural gas, published by the Department of Climate Change, Energy, the Environment and Water (DCCEEW).
Citation: DCCEEW (2025). Australian National Greenhouse Accounts Factors 2025. Commonwealth of Australia. Available at: https://www.dcceew.gov.au/climate-change/publications/national-greenhouse-accounts-factors-2025
Notes
Combined Scope 1 factor of 234.05 kg CO₂-e/GJ = CO₂ 234 + CH₄ 0.03 + N₂O 0.02 (NGA Factors 2025, Table 5). Energy content 0.004 GJ/m³ — a very lean gas, so volumes are enormous relative to energy. 1 GJ of blast furnace gas combusted = 234.05 kg CO₂-e, roughly 4.5 times the natural gas factor.
Calculation Example
If your steelworks combusted 1,200 GJ of blast furnace gas in hot blast stoves:
| Working | Result |
|---|---|
| 1,200 GJ × 234.05 kg CO₂-e/GJ = 280,860 kg CO₂-e | 280.86 tonnes CO₂-e (Scope 1) |
No gaseous fuel in the Australian emission factor tables comes close to blast furnace gas. At 234.05 kg CO₂-e per gigajoule, this dilute, carbon-monoxide-bearing by-product of iron making emits roughly 4.5 times more than natural gas per unit of energy — and every gigajoule a steelworks recovers and burns is reported in its Scope 1 inventory.
The economics still favour burning it, because the gas exists whether or not you use it. This entry covers the factor, the reasoning, and the calculations.
Quick Verdict
Blast furnace gas has a combined Scope 1 emission factor of 234.05 kg CO₂-e per gigajoule under the NGA Factors 2025 (Table 5) — CO₂ 234 plus negligible CH₄ and N₂O — with a very low energy content of 0.004 GJ/m³. It is the most emissions-intense gaseous fuel Australia publishes a factor for, the product of a gas that carries abundant carbon but little energy. The factor applies to integrated steelworks combusting recovered furnace offgas in hot blast stoves, boilers and on-site power plants, reported under Scope 1. Despite the headline number, recovery beats flaring: the gas is an unavoidable by-product, and using it displaces purchased fuel that would add CO₂-equivalent emissions on top.
How to Calculate Blast Furnace Gas Emissions
Emissions (kg CO₂-e) = Energy consumed (GJ) × 234.05 kg CO₂-e/GJ
Convert cubic metres at 0.004 GJ/m³ and megajoules at 1,000 MJ per GJ.
Worked Example 1: On-site power plant
A steelworks power plant combusts 50,000 GJ of blast furnace gas over the year.
50,000 GJ × 234.05 = 11,702,500 kg CO₂-e
11,702.50 tonnes CO₂-e (Scope 1)
Worked Example 2: Hot blast stoves
Hot blast stoves consume 1,200 GJ of recovered gas.
1,200 GJ × 234.05 = 280,860 kg CO₂-e
280.86 tonnes CO₂-e (Scope 1)
Worked Example 3: Furnace offgas metered in cubic metres
Instrumentation records 2,000,000 m³ of blast furnace gas sent to combustion.
2,000,000 m³ × 0.004 GJ/m³ = 8,000 GJ
8,000 GJ × 234.05 = 1,872,400 kg CO₂-e
1,872.40 tonnes CO₂-e (Scope 1)
How blast furnace gas compares with other gaseous fuels
| Gaseous fuel | Combined Scope 1 factor (kg CO₂-e/GJ) |
|---|---|
| Hydrogen | 0.05 |
| Landfill biogas | 6.43 |
| Coke oven gas | 37.08 |
| Natural gas (pipeline) | 51.53 |
| Coal mine waste gas | 56.80 |
| Town gas | 60.27 |
| Blast furnace gas | 234.05 |
NGER and AASB S2 Reporting
Blast furnace gas combustion is reported as Scope 1 under the NGER scheme, distinct from the industrial process emissions of iron making, and Australia’s integrated steel facilities sit far above every reporting threshold. Under AASB S2 the same emissions feed the disclosed Scope 1 inventory — meter blast furnace gas and coke oven gas separately, since their factors differ by a factor of six.
Related Emission Factors
Frequently Asked Questions
Disclaimer
This page is provided for general information, not professional or compliance advice. The factor shown is reproduced from the official publication cited above, and while we work to keep it current, government factors change — the publication is always the authoritative source.
- Before using this value in any formal reporting — including under the National Greenhouse and Energy Reporting Act 2007 — confirm it against the current official publication and the methods specified by the Clean Energy Regulator.
- NetNada is independent of the Australian Government, DCCEEW, and the Clean Energy Regulator. Government data is Crown copyright, Commonwealth of Australia.