Iron and Steel coke

Summary

This methodology represents carbon dioxide (CO₂) and methane (CH₄) emissions associated with the production of coke. The data and calculation methodology is sourced from the Greenhouse Gas Protocol (GHGP) worksheet tool CO2 emissions from the production of iron and steel, version 2.0, which is ultimately based on the methodologies described in Volume 3, Chapter 4 - Metal Industry Emissions of their 2006 IPCC Guidelines for National Greenhouse Gas Inventories.

The methodology

Emissions model

Metallurgical coke is the solid product obtained from the carbonisation of coal (predominantly 'coking coal' ) at high temperature, and is used as a blast furnace feedstock in the production of iron and steel. As well as producing coke, this process produces coke oven gas, CO₂, CH₄ and other by-products.

This methodology enables the calculation of coke-associated CO₂ emissions based upon a mass balance approach that accounts for the carbon inputs and outputs to coke ovens. By considering the carbon entering the process via the carbon-bearing feedstocks (typically coking coal, blast furnace gas and other materials), and the carbon leaving the process within coke, oven gases and other by-products, the discrepancy can be assumed to have been emitted as CO₂.

CH₄ emissions are based on an emissions factor which describes the rate at which CH₄ is emitted per unit quantity of coke produced. This includes iron converted, and not converted, into steel.

This methodology represents the IPCC Tier 2 approach where default carbon content data is used for carbon-bearing feedstocks and products, but Tier 3 where these are based on facility-specfic data.

Model data

This methodology is based on a mass-balance of process inputs and outputs, and depends upon quantities and carbon concentrations for each. Default carbon content data is provided for a selection of 21 carbon-bearing feedstocks (including blast furnace gas) as well as the coke and coke oven gas (by-)products for cases where facility-specific data is not available.

Activity data required

CO₂ emissions require quantities of feedstocks (including blast furnace gas specifically) and of coke, coke oven gas and other (by-)products in order to calculate. In addition, the methodology enables the specification of facility-specific data carbon content data where this is available. CH₄ emissions also require the quantity of coke produced to be specified. A default emissions factor for CH₄ is available but can be specified if facility- or country-specific data is available.

Calculation and results

CO₂ emissions are calculated by the mass-balance of the specified input/output activity data. CH₄ emissions are calculated by multiplying the quantity of coke specified by the appropriate emissions factor. CO₂e emissions are also calculated by converting absolute emissions using the appropriate global warming potentials.

Related methodologies

If feedstock and by-product data is unavailable, a simpler methodology based solely on quantities of coke produced is also available.

IPCC methodologies for other iron and steel-associated process emissions are also available, including tier 1 and tier 2/3 methodologies for iron and steel production, direct reduced iron and sinter production.