How does UK CBAM treat blast furnace or coke oven gas used as fuel in our plant?

The technical guide from HM Revenue and Customs (HMRC) for the UK Carbon Border Adjustment Mechanism (CBAM) treats a gas as waste gas only if it holds incompletely oxidised carbon, is gaseous and comes from a listed process. Waste gas coming in from another process takes natural gas's emission factor; gas sent out also takes 0.667.

Three tests for a waste gas

• It contains incompletely oxidised carbon, usually carbon monoxide.
• It is gaseous under standard conditions.
• It arises from one of the listed processes, such as reduction of metal compounds in ores, removal of impurities from metals, chemical syntheses where the carbon participates, or the use of carbon containing additives or raw materials.

Two more conditions on use

• The plant may not rely solely on waste gases. It must also be able to run stand-alone, so any waste gas used must be interchangeable with other fuels, for example natural gas.
• The waste gas supply should be metered, so the volume consumed by the process is known.

The two formulas

• Waste gas coming into the process from a different process: volume imported x net calorific value (NCV) x the standard emission factor of natural gas (equation 43 of the force of law notice).
• Waste gas sent out to a different process, where the operator can provide sufficient evidence for verification: volume exported x NCV x the standard emission factor of natural gas x a factor of 0.667 for the efficiency difference between waste gas and natural gas (equation 44).
• Keep the evidence for the verifier and document the method in the monitoring plan.

Why this matters in India

HMRC says recovering waste gases to make heat or electricity is preferable to venting or flaring them. Our reading: for a plant that sends coke oven gas to a power unit, the formulas decide how much of that gas's emissions stay with the steel and how much follow the gas.

Example: 5 million normal cubic metres sent to another process

• Volume exported: 5,000,000 Nm3 (normal cubic metres)
• NCV: 0.0000034 terajoules (TJ) per Nm3, which is 3.4 megajoules per Nm3
• Energy: 5,000,000 x 0.0000034 = 17 TJ
• Natural gas standard factor: 56.1 tCO2/TJ (Table 4, HMRC draft notice)
• Exported gas, equation 44: 17 x 56.1 x 0.667 = 636 tCO2 (636.1 before rounding)
• The same 17 TJ arriving at the receiving process, equation 43: 17 x 56.1 = 954 tCO2 (953.7)

The volume and NCV are example values, not a plant's. tCO2 means tonnes of carbon dioxide.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records. The standard product does not meter gas flows (metering is a custom installation on request) and does not work out the waste gas split. Buying records show the fuels you purchase, not the gases made on site. A verifier accredited for UK CBAM must still verify the figure.

• Standard fuel emission factors
• What a UK CBAM monitoring plan holds
• Sponge iron and the waste gas default
• UK CBAM for Indian exporters

Sources: HMRC, Carbon Border Adjustment Mechanism (CBAM): technical guide for monitoring, reporting and verification, HMRC, The Carbon Border Adjustment Mechanism (Emissions and Verification) Force of Law Notice (Draft)

Last reviewed 2026-11-06. Read from technical guide section D4.8.5 on 6 November 2026; the standard natural gas factor is from Table 4 of HMRC's draft Emissions and Verification notice, which HMRC may change before 1 January 2027.