Why in News?

• India aims to become a developed country by 2047 and achieve net-zero emissions by 2070.
• Decarbonising the construction sector is essential to meeting both objectives, as construction depends heavily on energy-intensive materials such as cement and steel.
• The construction sector accounts for an estimated 35–40% of global greenhouse gas (GHG) emissions, considering the broader built environment and its supply chains.
• Cement alone contributes approximately 7–11% of global CO₂ emissions, making it one of the hardest sectors to decarbonise.

What’s in Today’s Article?

• India’s Cement Industry
• Understanding Cement’s Environmental Footprint
• India’s Cement Decarbonisation Challenge
• Existing and Proposed Solutions
• Traditional Materials and Indigenous Construction
• Way Forward

India’s Cement Industry:

• Overview:
  • India is the 2nd-largest cement producer in the world, with an installed capacity of roughly 668 to 700 million tonnes per annum (MTPA).
  • Cement became the dominant construction binder following the development of Portland cement in Britain in the 1820s.
  • Its popularity stems from its versatility, availability, ease of use and relatively rapid strength development.
• Key facts:
  • Production volume: Reached ~490 million metric tonnes in FY26, showing an 8.6% year-on-year growth.
  • Demand drivers: Housing (accounting for about 65% of demand), commercial real estate, and large-scale public infrastructure projects like PM Gati Shakti.
  • Per capita consumption: Roughly 280 to 290 kg per year, which is lower than the global average.
  • Core industry: It is designated as one of India's eight core industries, carrying a weight of 5.37% in the Index of Industrial Production (IIP).
  • Regional distribution: South India holds the largest share of installed capacity at approximately 32%.
  • Key limestone-rich states: Rajasthan, Andhra Pradesh, Tamil Nadu, and Chhattisgarh.
  • Major cement companies: UltraTech Cement (largest player in India with a market share of around 22%–28%); Adani Cement (Ambuja Cements & ACC); Shree Cement, etc.

Understanding Cement’s Environmental Footprint:

• Energy-intensive manufacturing:
  • Limestone is extracted through mining, often involving the removal of vegetation and topsoil. It is then mixed with clay and heated in kilns to approximately 1,450°C.
  • Traditionally, coal, petroleum coke and natural gas have supplied the required heat. The high energy demand generates substantial emissions.
• Process emissions:
  • During calcination, limestone (calcium carbonate) decomposes into lime (calcium oxide) and carbon dioxide. This chemical reaction releases CO₂ independently of the fuel used.
  • The resulting material is processed into clinker, which is ground with gypsum and, depending on the cement type, other supplementary materials.
• Wider environmental impacts:
  • Cement's environmental footprint extends beyond factory emissions and includes -
    • Land degradation: Limestone mining can destroy vegetation, disturb habitats and alter landscapes.
    • Air pollution: Manufacturing releases nitrogen oxides, sulphur dioxide and particulate matter, affecting air quality and human health.
    • Transportation emissions: Moving raw materials and finished cement over long distances adds to the carbon footprint.
    • Loss of carbon sinks: Deforestation and vegetation loss reduce natural carbon sequestration.
    • Resource depletion: Intensive extraction places pressure on mineral resources and local ecosystems.
  • Therefore, a life-cycle approach is necessary to assess the environmental costs of cement production, transportation, construction and subsequent building use.

India’s Cement Decarbonisation Challenge:

• India's cement industry emits approximately 0.62 tonnes of CO₂ per tonne of cement. A decarbonisation roadmap must identify the following targets -
  • Reduce emissions intensity to 0.56 tonnes of CO₂ per tonne of cement by 2030.
  • Further reduce it to 0.51 tonnes by 2047.
• At the same time, cement production is projected to increase to 1,546 million tonnes by 2070, reflecting India's expanding infrastructure and urbanisation needs.
• This creates a major policy challenge - reducing emissions intensity while preventing rising production volumes from undermining absolute emission reductions.

Existing and Proposed Solutions:

• Cleaner fuels and energy:
  • Electrification, renewable energy and alternative fuels can reduce dependence on fossil fuels in cement manufacturing.
  • Refuse-derived fuel (RDF), produced by processing combustible fractions of municipal solid waste, can partially replace coal and petroleum coke in cement kilns.
  • NITI Aayog's roadmap recommends achieving a 20% thermal substitution rate using RDF by 2030, potentially reducing cumulative emissions by approximately 80 million tonnes of CO₂-equivalent.
  • However, this requires effective waste segregation at source, reliable waste-processing infrastructure and quality control.
• Reducing clinker content:
  • India's clinker-to-cement ratio is around 67.5%, already below the global average of 77%, but further reductions remain possible.
  • Builders often prefer Ordinary Portland Cement (OPC contains more than 95% clinker), because of its established performance and faster early-strength development.
  • Replacing a portion of clinker with supplementary cementitious (gypsum and fly ash) materials can substantially reduce emissions (Replacing one tonne of clinker can avoid approximately 0.83 tonnes of CO₂ emissions - IEA).
  • Green cement adoption can be encouraged through government procurement, revised construction specifications, performance-based standards and awareness among developers.
• Carbon capture, utilisation and storage (CCUS):
  • Cement cannot be fully decarbonised through fuel substitution alone because calcination generates process emissions. CCUS may therefore be necessary to address residual emissions.
  • However, its large-scale deployment will require technological improvements, investment, suitable transport and storage infrastructure, and effective monitoring.
• Sustainable building design:
  • Reducing cement demand through better architectural planning can complement cleaner manufacturing.
  • Climate-responsive buildings that minimise heat gain and heat storage can reduce cooling requirements and operational energy consumption.

Traditional Materials and Indigenous Construction:

• India's diverse climatic and geographical conditions have produced construction techniques that can reduce dependence on conventional cement-based systems.
• For example,
  • Compressed earth blocks and rammed earth: Used in parts of southern India, often with small quantities of cement or lime.
  • Lime-surkhi mortar: Combines lime with finely powdered burnt clay or brick material.
  • Natural binders: Cactus-derived mucilage, lime and mud, and certain industrial by-products such as marble powder can be explored in suitable applications.
  • Kath Kuni architecture: Traditional Himachal Pradesh construction uses alternating timber and dry-stone masonry, often supported by a raised stone plinth.
  • Elevated timber and bamboo houses: Found in flood-prone and earthquake-prone regions, particularly parts of northeastern India.
• These methods can offer locally appropriate, resource-efficient solutions. However, they are not universally suitable and may require adaptation to meet modern requirements.
• The objective should be to reduce cement use wherever technically appropriate, rather than eliminate it indiscriminately.

Way Forward:

• Strengthen circular economy practices: Improve waste segregation and utilise suitable industrial by-products, including fly ash and slag (Example, PPC and PSC).
• Improve regulatory and market incentives: Encourage low-carbon building codes, green public infrastructure and transparent disclosure of embodied carbon.
• Balance sustainability with affordability: Ensuring that low-carbon materials remain accessible and using cement more efficiently.