Cement, Energy and Environment

41 reduce fossil CO 2 . In India these are biomass (like rice husk, bagasse, plantation waste), industrial wastes (used tyres, solvents, sludge), and municipal refuse-derived fuel (RDF). The use of fly ash, slag, and other by-products as part-cement replacements in the kiln or blended cement is also included. Research into belite-rich clinker phases and alternative binders like calcium sulfoaluminate (CSA) cements shows potential to fundamentally alter the emissions profile [WBCSD, 2023]. Adoption is incremental but progress is being made. For example, UltraTech Cement only uses alternative fuels for ~5.2% of fuel requirements. India’s plan predicts this could go up to 35% by 2070. Some firms have established in-between targets – an industry publication mentions a target of ~10% AFR by 2025–26 (including biomass and waste) to cut the use of coal. Similarly, substitution of clinker is on a large scale: blended cements such as Portland Pozzolana Cement (PPC, with fly ash) and Portland Slag Cement (PSC) are ubiquitous, and newer forms such as Portland Limestone Cement (PLC) and Limestone Calcined Clay Cement (LC3) are being launched [EPFL, 2022]. As per the roadmap, clinker factor is to decline from 0.75 (2020) to 0.56 by 2070 through blends – i.e., much less limestone must be calcined. Some plants today already co-process wastes and byproducts, but economic limitations keep them from being widely used: blended cements compare with standard cement on price, and fly ash could become less available as coal plants go offline. ELECTRIFICATION OF PROCESS HEAT Cement kilns historically fire coal or petcoke at ~1500 °C. Electric heating provides an opportunity to decarbonize if the power is renewable. New technology is on the horizon: electric arc calciners, plasma or microwave heating, and electric RotoDynamic Heaters to substitute fuel-fired burners. Indian producers are testing such systems. Late in 2023 Dalmia Cement joined with Sweden’s SaltX to trial a fuel-free electric arc calciner at its Rajgangpur (Odisha) factory. UltraTech Cement has signed an agreement with Finland’s Coolbrook to commission a RotoDynamic Heater (RDH) at one of its plants, to employ clean electric heat for firing and drying. JSW Cement will also employ Coolbrook’s RDH at its Vijayanagar plant (Karnataka) to heat its slag-cement process. These pilots intend to end fossil fuel burning in kiln processes, but hurdles exist: electric kilns have enormous power requirements and are as clean as the grid or local renewables. Still, if ramped up, electrified kilns could sharply reduce emissions, as 100% renewably-powered heat would end stack CO 2 (aside from the intrinsic calcination CO 2 ). AI/IOT AND PROCESS OPTIMIZATION Digital technologies are making process control smarter. Cement plants areadding IoT sensors and employing AI/ML to track and optimize operations: from accurate fuel feeding and preheater temperature control to predictive maintenance of kiln fans and mill drives. Industry analysis observes that AI can deliver energy savings by optimizing raw mix, kiln zones, and minimizing fuel variability. In reality, plants with sophisticated control systems (e.g. model predictive controllers) have achieved noticeable reductions in energy. With “Industry 4.0” solutions expanding, Indian cement companies are deploying sensors and data analysis to drive out efficiencies and cut time down. In the long run, these software systems will be supplemented by hardware improvements, to make thermal and electrical consumption more efficient with little extra emissions. CARBON MINERALIZATION AND NOVEL MATERIALS Aside from engineered CCUS, carbon mineralization is an emerging field. Geological research indicates that India’s vast basalt basins would be able to store CO 2 safely underground through conversion into stable minerals. Industry is also investigating ex-situ carbonates in the near term: e.g., injecting CO 2 into fresh concrete (e.g., in “carbon cure” technologies) or introducing cement additives that uptake CO 2 as calcium carbonate. Carbonated concrete research in India is in its infancy, but worldwide it holds promise. At the same time, bio-based products (such as biomasspyrolysisbiochar)arebeingexperimented withas partial cement substitutes, which sequester biogenic carbon within the concrete. Certain start- ups globally (e.g. CarbonCure, CarbonBuilt) are working on methods to supply CO 2 to cementitious mixtures. In India, they are largely at the laboratory phase, but interest is increasing in making cement go from a carbon source to a carbon sink, even at the periphery. GREEN HYDROGEN INTEGRATION Greenhydrogen (made fromrenewables)provides another option: it canbeusedasacarbon-free fuel,