Carbon Intensity

Carbon intensity is a normalized measure expressing the quantity of greenhouse gas (GHG) emissions generated per unit of economic output, energy consumed, or physical product produced by a mining operation or process, enabling meaningful comparison of emissions performance across operations of different sizes, comparing performance over time, and benchmarking against industry peers. Common carbon intensity metrics in the mining industry include tCO₂e per tonne of ore mined, tCO₂e per tonne of mineral or metal produced, tCO₂e per GJ of energy consumed, and tCO₂e per tonne of commodity shipped. In bauxite mining and alumina refining, carbon intensity is typically expressed as tonnes of CO₂e per tonne of alumina produced, which varies widely depending on refinery energy source, process efficiency, and fuel type — from approximately 0.4 tCO₂e/t alumina for highly efficient refineries using natural gas with heat integration, to over 1.5 tCO₂e/t alumina for refineries using heavy fuel oil or coal. In aluminum smelting, carbon intensity is expressed as tCO₂e per tonne of aluminum, with world-class smelters achieving around 1.5-2.0 tCO₂e/t Al (Scope 1 and 2), while less efficient, coal-powered operations can exceed 10 tCO₂e/t Al. In gold mining, carbon intensity (tCO₂e per troy ounce produced) varies enormously by ore grade, processing method, and energy source — a critical consideration given that low-grade open-pit operations with heap leaching are fundamentally less carbon-efficient per unit of metal than high-grade underground operations. Carbon intensity metrics allow mining companies to set meaningful emissions reduction targets (e.g., 30% reduction in carbon intensity by 2030 from 2020 baseline), track progress against targets independent of production volume changes, and communicate performance to investors and regulators.