ENVIRONMENTAL SUSTAINABILITY OF BIOFUELS IN INDIA: AN LCA APPROACH

Abstract

The increasing global demand for energy, coupled with the environmental consequences of prolonged reliance on fossil fuels, has intensified the search for sustainable, renewable energy alternatives. Among these, biofuels have emerged as a promising solution due to their potential to reduce greenhouse gas emissions, enhance energy security, and support rural economies. In the Indian context, rapid industrialization, urbanization, and population growth have further increased energy demand, making the transition to cleaner fuels both an environmental necessity and a strategic priority. Bioethanol and biodiesel, as liquid biofuels compatible with existing infrastructure, have gained significant attention; however, their environmental sustainability varies considerably depending on feedstock selection, production processes, and regional conditions. Therefore, a comprehensive evaluation from a life cycle perspective is essential to ensure that hidden burdens across the different stages of production and use do not offset their perceived environmental benefits. This research systematically evaluates the environmental sustainability of bioethanol and biodiesel production in India using a Life Cycle Assessment (LCA) framework. For bioethanol production, diverse feedstocks, including molasses, broken grains, agricultural residues (rice straw, corn stover, cassava straw), and municipal solid waste, are assessed. At the same time, biodiesel pathways include edible oil-based (rapeseed, palm oil, palm stearin), non-edible oil-based (jatropha), waste-derived (used cooking oil), and third-generation (microalgae) feedstocks. A cradle-to-gate approach is adopted to quantify impacts across multiple categories, such as global warming potential, resource depletion, water consumption, toxicity, and ecosystem damage, using ReCiPe 2016, IMPACT 2002+, and IMPACT World+ methods, complemented by cumulative energy demand analysis and Monte Carlo simulation to ensure statistical robustness and uncertainty characterization. The results demonstrate that environmental performance is strongly feedstock-dependent across both biofuel systems. In bioethanol production, global warming impacts range from 3.3 to 3.8 kg CO₂ eq, with significant contributions from ecotoxicity categories (up to 7.21 kg 1,4 DCB eq), largely driven by energy-intensive stages such as pre-treatment, enzymatic vii Environmental Sustainability of Biofuels in India: An LCA Approach hydrolysis, and distillation. First-generation pathways, such as molasses and grain, exhibit moderate impacts but are heavily influenced by electricity and steam consumption, whereas second-generation feedstocks, such as agricultural residues, demonstrate comparatively lower impacts and improved resource efficiency due to waste valorization. However, MSW-based bioethanol exhibits poor energy performance (NER = 0.48, NEV = −47.39 MJ, NRnEV = −23.63 MJ) despite its circular-economy advantages. In biodiesel systems, substantial variation is observed across feedstocks, with palm oil and microalgae exhibiting the highest environmental burdens (5.92 and 5.89 kg CO₂ eq, respectively), primarily due to intensive agricultural inputs and energy consumption during cultivation and processing. In contrast, waste derived biodiesel from used cooking oil demonstrates the lowest impacts and minimal fossil resource use (0.15 kg oil eq), indicating strong environmental and circularity benefits. Non-edible feedstocks such as jatropha have moderate impacts, whereas rapeseed biodiesel has relatively higher burdens due to fertilizer-intensive cultivation practices. These findings highlight that feedstock selection is a critical determinant of sustainability outcomes in biodiesel production. Energy analysis further reveals that most agricultural residue-based bioethanol systems are energy-positive, with NER values up to 4.19 and NEV values around 32–33 MJ, indicating favorable net energy gains and reduced dependence on fossil fuels. Similarly, biodiesel from UCO demonstrates superior energy efficiency (NER = 5.49) and a lower cumulative energy demand than conventional feedstocks. Across both biofuel systems, key environmental hotspots include electricity consumption, steam generation, fertilizer use, and chemical inputs, emphasizing the need for process optimization and integration of renewable energy sources. Uncertainty analysis indicates low to moderate variability across most impact categories, with coefficients of variation generally between 4% and 10%, confirming the robustness and reliability of the model outputs. The probabilistic distributions follow near-lognormal behavior with well-defined confidence intervals, although higher variability is observed in toxicity-related categories, reflecting sensitivity to input parameters and underlying assumptions. The comparative assessment highlights that second-generation and waste-derived biofuels consistently outperform first-generation systems in environmental and energy performance, whereas third-generation pathways, such as microalgae, require further viii Environmental Sustainability of Biofuels in India: An LCA Approach technological advancements to reduce their energy and nutrient intensity. From a policy perspective, the findings support the promotion of non-edible and waste-based feedstocks, improved process efficiency, and the integration of renewable energy within biofuel production systems. In conclusion, this study provides a comprehensive, quantitative evaluation of the sustainability of bioethanol and biodiesel in India, demonstrating that their environmental performance is shaped by a complex interplay of feedstock characteristics, production technologies, and energy inputs. The integration of LCA, energy analysis, and uncertainty assessment provides a robust decision-support framework for identifying critical hotspots and guiding the development of sustainable biofuel systems aligned with climate mitigation, resource efficiency, and circular-economy objectives.