The Impact of and Cut-Off Criteria for Auxiliary Consumables in Quantifying the CFP of Hard Coal: A Case Study of Typical Coal Mines in China

Accurate carbon footprint quantification for hard coal products is essential for the development of low-carbon and sustainable supply chain emissions management. A significant challenge lies in handling the numerous auxiliary consumables used in mining, whose contributions to upstream emissions are often unclear. This study addresses this gap by calculating the cradle-to-gate carbon footprint of hard coal from typical surface and underground mines in China using a life cycle assessment. Confronted with the challenge of accounting for thousands of consumable types, this study demonstrates that economic cost is an ineffective criterion for identifying high-impact items. In contrast, consumable weight shows a strong correlation with emissions and provides a robust basis for cut-off decisions. CFP quantification results obtained using this method show that upstream emissions from other auxiliary consumables (OACs), except for fuel and explosives, account for a significant proportion of the total CFP: 1.64 ± 0.50% (1.02 ± 0.31 kg CO2e/t) in a surface mine and 11.63 ± 3.17% (2.91 ± 0.87 kg CO2e/t) in an underground mine. Based on three years of requisition data and an emission analysis, a reference list of the OACs that need to be included is provided, which can serve as a reference for determining the cut-off criteria for and system boundary of the carbon footprint of hard coal products and thus promote the better development of sustainable supply chains.