Ferroalloy methane emissions

The category business/processes/production/ferroalloy/ch4 is aimed towards industry professionals to enable them to prepare inventories of greenhouse gas emissions from ferroalloy production. This category is designed for use alongside the ferroallloy tier 1 or tier 2 categories. The methodology provided in this category represents the Tier 1 (default) and Tier 2 (user-supplied) approach for CH₄ emissions calculation described by the IPCC Guidelines for National Greenhouse Gas Inventories (NGGIP).

The heating of carbon materials in the furnace releases volatiles including methane. With open or semi-covered furnaces – predominantly used for FeSi and Si ferroalloy production - most of the volatiles will burn to CO₂ above the charge, in the hood and off-gas channels, but some will remain un-reacted as CH₄ and NMVOC. The amounts depend on the operation of the furnace. Sprinkle-charging will reduce the amounts of CH4 compared to batch-wise charging. Increased temperature in the hood (less false air) will reduce the content of CH₄ further. The errors associated with estimates or measurements of N2O emissions from the ferroalloys industry are very large and thus, a methodology is not provided.

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How to use this category

Selecting an emissions scenario

To use this category use the typeOfAlloy drill-down to select the alloy type being used from the following options:

1. si-metal
2. fesi 90
3. fesi 75
4. fesi 65

A second drill-down must then be specified using the operationOfFurnace drill-down to select the operation type of the furnace used, from the following options:

1. unknown
2. batch-charging
3. sprinkle-charging
4. sprinkle-charging and over 750 degrees C

If unknown is selected, the default values used are those for sprinkle-charging operation.

Specifying activity data

The only required profile item value is productQuantity. The emission factor has a default value provided by the CarbonKit engine, but this can be over-ridden, using the massCO2PerMassProduct profile item value, by the user if more precise site or country-specific values are known. If using a site-specific emissions factor, the calculation represents the tier 2 IPCC NGGIP methodology.

Results and calculation

The returned amounts represent the CH₄ emissions associated with the quantity specified. Two quantities are returned, as follows:

• CH4: CH₄ (methane) emissions
• CO2e: CO₂e emissions (CH₄ converted using these global warming potential)

The individual quantity for CH₄ represents an absolute quantity rather than a CO₂e quantity.