Lime: Emissions
Why the rock itself releases most of the CO2
What this tab covers The greenhouse-gas footprint of the commodity at a global level, split by lifecycle phase: extraction (or farming), refining and processing, movement, usage, and recycling or end of life. Intensities are per unit of product; the global total combines intensity with world output. Also covers other environmental impacts and the main levers to cut emissions. Emission intensity 1.10 t CO2e per t range 0.9-1.5 · cradle-to-gate; process CO2 of about 0.75-0.79 t/t plus kiln fuel of about 0.2-0.6 t/t depending on kiln type and fuel Global emissions per year 460 Mt CO2e per year 2025 · intensity of about 1.1 t/t times 420 Mt output; indicativePer t of quicklime, cradle-to-gate. Intensity: Stoichiometry; IPCC 2006 Guidelines default 0.75 t CO2/t high-calcium lime; EuLA (indicative). Global total: Derived from USGS MCS 2026.
Share of footprint by lifecycle phase
Extraction 1% Refining / processing 96% Movement 3%Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | about 0.005-0.01 t CO2e/t lime (indicative) | 1% | quarry blasting, loading and haulage of about 1.8 t limestone per t of lime | small | Derived; ecoinvent-based quarrying values (indicative) |
| Refining / processing | about 1.0-1.4 t CO2e/t lime | 96% | process CO2 from CaCO3 to CaO (about 70% of the total) plus coal, petcoke or gas fuel | Shaft kilns use about 3.5-4.5 GJ/t; long rotary kilns about 6-9 GJ/t (indicative); process CO2 cannot be cut by fuel switching | EU BREF Cement, Lime and Magnesium Oxide 2013 (indicative); stoichiometry |
| Movement | about 0.01-0.03 t CO2/t (indicative) | 3% | truck and rail delivery within a few hundred km | seaborne lime to mining hubs adds more | Derived; road and rail factors (indicative) |
| Usage | part of the process CO2 is reabsorbed in use | – | lime reacts back to carbonate in mortar, soil, water treatment and precipitated calcium carbonate | EuLA estimates up to about a third of process CO2 may be re-absorbed over time (indicative); use in flue-gas scrubbing removes SO2 and HCl | EuLA recarbonation study (indicative) |
| Recycling / end of life | regenerated lime avoids new quarrying but still re-releases CO2 when re-burned | – | pulp mill lime mud and water softening sludge re-burned in kilns | regenerated volumes excluded from USGS output; EU recycling input rate for limestone 1% | USGS MCS 2026; EU CRM 2023 |
Other environmental impacts
Kilns emit dust, NOx and SO2. Quarries change landscapes. Lime is caustic, so handling injuries and spills matter.
Levers to cut emissions
- Carbon capture on kiln flue gas, the only route for the 0.75-0.79 t/t of process CO2 (Mississippi Lime and Fortera pilot)
- Replace long rotary kilns with parallel-flow regenerative shaft kilns using about half the fuel (indicative)
- Switch fuel from coal and petcoke to gas, biomass or hydrogen
- Count and credit recarbonation in mortar and PCC
India
India is the second-largest lime maker at about 17 Mt (USGS 2025), much of it from small coal-fired shaft kilns and captive kilns at steel and sugar plants, so fuel intensity is likely above EU averages; no Indian intensity figure is published (indicative).
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.