Lime

This provides data and calculation methodologies to facilitate the measurement and monitoring of greenhouse gas emissions resulting from lime manufacturing. Major consumption of lime (CaO) stems from steel making, flue gas desulphurisation at coal-fired electric power plants, construction, pulp and paper manufacturing and water purification. Calcination is the process by which limestone, which is mostly calcium carbonate (CaCO₃), is heated in a kiln to produce lime. Carbon dioxide is a byproduct of this reaction and is usually emitted to the atmosphere. Some facilities recover a portion of the emissions for use in sugar refining and precipitated calcium carbonate production.

There are several methodologies for lime production:

• IPCC Tier 1 production-based methodology: this methodology calculates emissions based upon a generic emissions factor for CO₂ emissions per quantity of lime produced and a default breakdown of lime types. The methodology is sourced from the IPCC 2006 Guidelines for National Greenhouse Gas Inventories and represents the Tier 1 approach.

• IPCC Tier 2 production-based methodology: this methodology calculates emissions using production data and is sourced from the WRI Greenhouse Gas protocol worksheets but ultimately follows the IPCC 2006 Guidelines for National Greenhouse Gas Inventories. Emissions are disaggregated on the bases of the types of lime produced and corrected for the production of any hydrated lime and any uncalcined lime kiln dust (LKD) that is not recycled to the kiln. This category represents the IPCC Tier 2 approach.

• IAI production-based methodology: The category business/processes/production/lime/production/iai provides a methodology sourced from The Aluminium Sector Greenhouse Gas Protocol published by the International Aluminium Institute in conjunction with the WRI Greenhouse Gas Protocol. The methodology is based on the quantity and purity of 'quick' (calcium oxide; CaO) and 'slaked' (calcium hydroxide; Ca(OH)₂) lime produced. The CO₂ emissions associated with this lime production is based on the known ratio in which lime and CO₂ are produced during carbonate calcination.

• Inputs-based methodology: this methodology calculates emissions using data on the carbonate composition of the raw material feed and is sourced from the WRI Greenhouse Gas protocol worksheets but ultimately follows the IPCC 2006 Guidelines for National Greenhouse Gas Inventories:. Emissions are disaggregated on the basis of the types of carbonates used and are corrected for LKD and the fraction of each carbonate species that remains uncalcined following lime production. This category represents the IPCC Tier 3 approach.