2023 · GS Paper 3 · Q6 · 10 marks
Discuss several ways in which microorganisms can help in meeting the current fuel shortage.
In short
Microorganisms can ease India's fuel shortage by fermenting sugars into ethanol, digesting waste into biogas, and producing algal biodiesel and biohydrogen. Yeast-based ethanol helped India reach 20% blending in petrol in 2025, while IOCL's Panipat 2G plant turns crop residue into fuel.
Model answer
Ghissu Editorial · Verified 4 Oct 2026 · 269 words
India imports over 85% of its crude oil (PPAC), so global shocks become domestic fuel shortages. Microorganisms can turn sugar, waste and sunlight into fuels, as promoted by the National Policy on Biofuels 2018.
Microbial Routes That Replace Fossil Fuels
1. Yeast bioethanol: Saccharomyces cerevisiae ferments molasses, cane juice and damaged grain into ethanol, enabling India's 20% blending in petrol in 2025. 2. Cellulose to ethanol: Trichoderma reesei enzymes turn crop residue into sugars for 2G ethanol, as at IOCL's Panipat plant (2022), easing stubble burning. 3. Biogas and CBG: Methanogenic archaea convert cattle dung, press mud and urban waste into methane, scaled under SATAT (2018) and GOBARdhan. 4. Algae and hydrogen: Microalgae like Chlorella and Botryococcus yield lipids for biodiesel, and Clostridium releases biohydrogen, neither needing fertile farmland.
Waste to power
Geobacter-based microbial fuel cells make electricity from wastewater, and microbial enhanced oil recovery extends old oil wells.
Energy security and farmers
Ethanol and CBG cut the oil import bill and add a new income stream for cane, maize and dairy farmers.
Cost and food trade-off
Costly enzymes and photobioreactors keep most output first generation, and grain ethanol's demand on food and water makes waste-based routes the sustainable priority.
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Question from the official UPSC Civil Services (Main) Examination 2023 paper. Answer written by Ghissu's engine and checked against our editorial standards. Found an error? Tell us and we correct it within 48 hours.