Decarbonisation of Cement Sector

Why is cement so difficult to decarbonise?

• Cement is structurally emission-intensive
  
• Cement production requires heating limestone to very high temperatures.
• Calcination releases CO₂ when limestone (calcium carbonate) is converted into a clinker.
• Cement kilns also require temperatures of around 1,450°C, creating substantial process and energy emissions.
• Around 60–65% of cement-making emissions arise from the chemical breakdown of limestone during calcination, while the remainder is associated largely with energy use.
• Limestone extraction itself can damage forests and fertile topsoil.
• Demand for cement is set to expand
  
• India’s cement production is estimated to increase from around 334 million tonnes in 2019–20 to 1,546 million tonnes by 2070.
• Without substantial changes in production methods, rising demand could offset efficiency gains.
• Cement has deep construction linkages
• Cement and concrete remain fundamental to housing, roads, bridges and infrastructure.
• The sector therefore cannot simply be eliminated; decarbonisation has to occur while construction continues to expand.
  
  

Why are low-carbon alternatives still difficult to scale? 

• High-temperature process: Cement production inherently requires very high temperatures.
• Process emissions: A large share of emissions comes from limestone chemistry rather than fuel combustion.
• Material availability: Fly ash and slag are useful substitutes but cannot meet all future cement demand.
• Cost: Low-carbon alternatives and carbon-capture technologies can be expensive.
• Construction standards: Developers and engineers often prefer conventional cement because its performance and supply chains are well established.
• Infrastructure dependence: Existing buildings and construction systems are designed around conventional cement and concrete.
• Alternative-material constraints: Traditional materials cannot simply replace cement across all forms of modern construction.

How can the cement industry reduce its carbon footprint?

• Reduce fossil-fuel dependence
  
• Cement plants can replace conventional fossil fuels with refuse-derived fuel (RDF) produced from processed municipal solid waste.
• RDF is shredded and sorted waste containing combustible material that can substitute part of the fossil fuel used in cement kilns.
• The roadmap discussed in the article recommends increasing the use of RDF and achieving 20% thermal substitution from municipal solid waste by 2030
• Reduce clinker content
  
• Increasing the use of fly ash, slag and other supplementary materials reduces the quantity of clinker required.
• Portland Pozzolana Cement (PPC) generally contains substantially less clinker than OPC.
• Greater clinker substitution directly reduces emissions associated with calcination.
• Improve waste segregation
  
• Effective RDF use depends on better segregation and processing of municipal waste.
• Improved waste management can therefore simultaneously address urban waste and industrial fuel demand.
• Explore carbon capture
  
• Carbon capture can address emissions that arise directly from limestone calcination and cannot be eliminated simply by switching fuels.
• However, high costs and technological requirements remain major barriers.

Conclusion:

India’s construction needs will continue to grow, but growth need not remain carbon-intensive. Cleaner energy, lower clinker use, alternative materials and circular resource use can align infrastructure expansion with India’s net-zero pathway.