Cement Energy & Environment

52 KEYWORDS: carbon-storing materials, nanomaterials, mineral carbonation, biogenic carbon, graphene oxide, life cycle assessment, India cement decarbonization, climate mitigation 1. INTRODUCTION 1.1 Global and Indian Context India is the world’s second-largest cement producer with installed capacity of 594.14 million tonnes (2022–23) and production of 361 million tonnes (2021–22). The sector’s carbon intensity stands at 0.64 kg CO 2 per tonne of cement (2024–25). Per capita cement consumption (260 kg annually) is significantly below the global average (540 kg), indicating substantial growth as India progresses toward its Viksit Bharat 2047 target. Cement demand is projected to rise from 445 million tonnes (2024) to 670 million tonnes by 2030, with cumulative CO 2 emissions from the sector potentially reaching 13 gigatonnes by 2050 without aggressive decarbonization. India’s commitment to achieve net-zero emissions by 2070 (with interim 2047 target) has positioned the cement sector as strategically critical. The Decarbonisation Roadmap for the Indian Cement Sector (GCCA India–TERI, March 2025) identifies eight key decarbonization levers, with carbon capture, utilization, and storage (CCUS) and cement-useefficiencyprojectedtocontribute25.1% and30.2%of total emission reductions, respectively. Current carbon-storing technologies include: (1) mineral carbonation (0.4–0.6 tonnes CO 2 / tonne sequestration), (2) CO 2 -cured blocks, (3) biochar integration from agricultural residues, (4) high-blend cements (Limestone Calcined Clay Cement—LC3, IS 18189:2023), and (5) nanomaterial-enhanced systems enabling synergistic effects. Major Indian cement manufacturers (UltraTech, Dalmia, Ambuja, ACC, JK Cement) are advancing innovation through five DST CCU testbeds (announced May 2025): oxygen-enhanced calcination (JK Cement + NCB, Haryana), solvent-based CO 2 capture (JSW Cement + IIT Kanpur), catalyst-driven capture (Dalmia + IIT Bombay), vacuum swing adsorption (CSIR-IIP + JSW), and oxygen-enriched burning with mineralization (UltraTech + IIT Madras). 1.2 Problem Statement and Research Gap While international LCA databases (Ecoinvent, KBOB) provide standardized environmental data, they lack India-specific parameters for: (1) regional raw material variability (fly ash from 140+ thermal plants,GGBFS fromdispersedsteelmills), (2)diverse electricity grids (45% renewables, 50% coal, with regional emission factorsvarying2.5×), (3)biogenic carbon accounting aligned with Indian agricultural practices, (4) scale-up uncertainties during technology commercialization, and (5) emerging nanomaterial lifecycle environmental impacts. R&D teams face critical disconnects: LCA tools (SimaPro, GaBi, openLCA) are designed for ex-post assessment of mature technologies, not early- stage design optimization. LCA outcomes remain disconnected from industry standards, regulatory frameworks (BIS codes, BEE criteria), and carbon market mechanisms (National Carbon Registry). This research adapts the U.S. ARPA-E HESTIA Program framework to India’s cement context, identifying India-specific LCA challenges, carbon sequestration pathways including nanomaterial-enhanced approaches, and their integration with policy frameworks. 2. CARBON SEQUESTRATION PATHWAYS AND DEMONSTRATION OUTCOMES 2.1 Primary Carbon Sequestration Routes Pathway 1: Mineral Carbonation (0.4–0.6 tonnes CO 2 /tonne) — Direct CO 2 mineralization converts atmospheric/captured CO 2 into stable carbonates. Indian pilot data (IIT Kanpur + JSW Cement testbed) demonstrates ~0.5 tonnes CO 2 / tonne sequestration over 50-year service life. Pathway 2: Biogenic Carbon Sequestration (0.2–0.4 tonnes CO 2 /tonne) — Agricultural residues (rice husk, peanut husk) converted to biochar stabilize biogenic carbon within concrete. Conservative estimates assume 25- year temporary storage (0.2–0.3 tonnes CO 2 / tonne) with 50% permanence beyond demolition. Pathway 3: Clinker Factor Reduction (0.1– 0.2 tonnes CO 2 /tonne) — LC3 cement (IS 18189:2023) reduces process emissions through increased supplementary cementitious material substitution. LC3 clinker factor of