India’s Cement Sector Stands in its way to Net-Zero Emissions

Syllabus: GS3/Environment 

Context

• India aims to become a net-zero emissions economy by 2070, achieving it requires the Indian government to reduce emissions from the construction sector.

About

• By 2047, India plans to become an economically developed country and by 2070, it aims to become a net-zero emissions economy.
  • Achieving both of these targets requires the Indian government to deal with one of the most important sources of emissions that is construction. 
• This sector consumes steel and cement, among other materials, and its footprint contributes 35% to 40% of all greenhouse gas emissions around the world.
  • Most of these emissions are because of the energy that the steel and cement sectors need to reach extremely high temperatures required for industrial processes. 
  • But even between the two, the cement sector also emits carbon when calcifying limestone.

Indian Cement Sector

• India is the world’s second‑largest cement producer after China, contributing about 13% of global annual cement output. 
• There are 333 cement manufacturing units in India comprising 159 integrated, large cement plants; 116 grinding units; 62 mini cement plants; and five clinkerization units 
• India’s production of about 391 Mt of cement results in roughly 246 MtCO2e of emissions i.e. around 6% of national greenhouse gas emissions. 
• Extraction of Limestone: Limestone is the raw material for cement. It is formed when calcium-rich marine life, such as oysters and corals, is fossilised and compressed over millions of years.
  • Accessing it requires miners to first clear forests and all layers of fertile soil in specific areas to expose the sedimentary rock layer. 
  • Limestone can be found 30-60 m under the topsoil in Karnataka, Chhattisgarh, and Andhra Pradesh and at more shallow depths in Rajasthan.
• Calcination:Limestone is mixed with clay and heated to around 1,450° C. This heating process alone accounts for 35% to 40% of emissions from cement-making; the rest comes from the chemical breakdown of limestone.
  • During the process it releases carbon dioxide as a by-product along with small stone-like balls called clinkers. 
  • They are crushed into powder and mixed in several ratios with gypsum and fly ash and sold as the various cement types available on the market.

Suggestions

• Traditional Building Materials: Lime mortar, used in structures such as the Taj Mahal, and lime-based binders combined with volcanic materials used in ancient Roman buildings demonstrate the potential of traditional alternatives.
• Refuse-Derived Fuel (RDF): Processed combustible waste can replace coal and petroleum coke in cement kilns.
  • NITI Aayog recommends achieving a 20% thermal substitution rate by 2030, potentially reducing emissions by around 80 million tonnes of CO₂ equivalent cumulatively.
• Reducing Clinker Content: Replacing clinker with industrial by-products such as fly ash and blast-furnace slag can reduce emissions.
  • According to the International Energy Agency, replacing one tonne of clinker can avoid approximately 0.83 tonnes of CO₂ emissions.
• Promoting Blended Cement: Portland Pozzolana Cement (PPC) and Portland Slag Cement (PSC) contain less clinker than Ordinary Portland Cement (OPC), making them lower-carbon alternatives.
• Carbon Capture, Utilisation and Storage (CCUS): Since limestone calcination releases CO₂ through a chemical reaction, even a shift to cleaner fuels cannot eliminate all emissions. CCUS is therefore an important option for addressing residual emissions.

Challenges in Adopting Green Cement

• Structural Performance and Strength: Builders often prefer OPC because it develops strength more quickly, whereas some blended cements take longer to gain strength.
• Industry Preference: The construction industry is deeply accustomed to conventional cement because of its established standards, supply chains, commercial availability and widespread use.
• Waste Management: Poor segregation of municipal solid waste limits the availability and quality of RDF for industrial use.
• Limited Substitution: Excessive replacement of clinker or conventional fuels may affect cement performance, depending on the materials and production process. Substitution must comply with technical and safety standards.
• Lack of Commercial Infrastructure: Traditional building materials and alternative binders often lack the standardisation, supply networks and large-scale manufacturing capacity available for cement.

Way Forward

• Government Procurement: Increase the procurement of certified low-carbon cement for public infrastructure projects to create initial demand and encourage wider adoption.
• Improve Waste Segregation: Strengthen source-level segregation, waste processing and RDF supply chains to enable cement plants to use more waste-derived fuels.
• Promote Research and Innovation: Invest in CCUS, alternative binders, energy-efficient kilns and low-carbon construction materials.
• Revise Construction Practices: Encourage architects, engineers and builders to adopt alternative materials and designs wherever technically suitable, supported by reliable testing and standards.

Source: TH