Climate Change / Industrial Emissions — UPSC Mains Model Answer

Cement manufacturing accounts for roughly 7–8% of global CO₂ emissions, exceeding the commonly cited 5% threshold. This makes it one of the largest single industrial sources of carbon dioxide, surpassing many other heavy industries. The sector's emissions trajectory is particularly concerning given rising infrastructure demand in developing economies.

Clinker production is the core emission-intensive stage: limestone (calcium carbonate) is heated to high temperatures, converting it into lime (calcium oxide) through calcination, releasing CO₂ as a by-product. This process-related emission is distinct from fuel combustion and cannot be eliminated through energy efficiency alone. Silica-bearing materials such as clay or shale are blended with limestone to provide the silica, alumina, and iron oxide needed for clinker chemistry.

Blended cements that substitute clinker with supplementary cementitious materials — fly ash, slag, or calcined clay — can substantially reduce process emissions. Carbon capture, utilisation, and storage (CCUS) technologies are being piloted at cement plants to intercept stack emissions. India's Bureau of Energy Efficiency has targeted cement as a priority sector under the Perform, Achieve and Trade scheme to drive energy intensity reductions.

Despite its emissions footprint, cement lacks a dedicated global sectoral decarbonisation treaty equivalent to those emerging for steel or shipping. Nationally Determined Contributions under the Paris Agreement rarely specify cement-sector targets with measurable baselines, leaving implementation to voluntary industry initiatives and fragmented national regulations.