Discuss several ways in which microorganisms can help in meeting the current fuel shortage.
Approach · directive: “discuss”
What it asks · Discuss the ways microbes can be used to produce gaseous, liquid and electrical energy, and how they can ease India's fuel shortage.
The question has 2 parts — answer each
- Discuss the several ways microorganisms can produce fuel: gaseous, liquid and electrical routes
- Show how these routes help meet the current fuel shortage, with their limits
Open with · India imports most of its crude oil, so fuels made by microbes from farm and urban waste offer energy security and waste management together.
Cover
- Biogas: methanogenic bacteria digest cattle dung, crop residue, food and sewage waste without oxygen; the methane serves as cooking fuel, power or compressed biogas (GOBARdhan, SATAT).
- Bioethanol: yeast ferments sugarcane juice, molasses and grain; petrol blending reached 10% in 2022 and 20% is targeted by 2025-26.
- Second-generation ethanol: cellulose-degrading microbes and enzymes convert farm residue such as paddy straw into ethanol, cutting stubble burning; a 2G plant runs at Panipat.
- Biodiesel and algal fuels: oil-rich microalgae and other microbes produce lipids that can be converted to biodiesel; used cooking oil is another feedstock.
- Other routes: biohydrogen from fermenting bacteria, microbial fuel cells that generate electricity from organic waste, and microbial enhanced oil recovery.
- Limits: food-versus-fuel competition, high cost and low yields of advanced routes and feedstock logistics; R&D, assured offtake and pricing support are needed.
Close with · Microbial fuels can meet only part of the shortage, but a waste-to-energy focus makes them sustainable and climate-friendly.
Question: UPSC's CS (Main) 2023, GS Paper III — paper ↗. Approach: Minimalist IAS, checked 30 Sept 2026 (how we verify) — UPSC publishes no model answers. ·
Model answer · 211 words (UPSC limit 150) · Minimalist IAS
India imports most of its crude oil, so fuels that microbes make from farm, animal and urban waste offer energy security and waste management in one stroke.
Microbial routes to fuel
- Biogas: methanogenic bacteria digest cattle dung, crop residue, food and sewage waste without oxygen; the methane serves as cooking gas, power or compressed biogas, supported by GOBARdhan and SATAT.
- Bioethanol: yeast ferments sugarcane juice, molasses and grain into ethanol; petrol blending reached 10% in 2022 and 20% is targeted for 2025-26.
- Second-generation ethanol: cellulose-degrading microbes and enzymes turn paddy straw and other residue into ethanol, as at the Panipat 2G plant, cutting stubble burning as well.
- Biodiesel: oil-rich microalgae and other microbes produce lipids that can be converted into biodiesel; used cooking oil is another feedstock.
- Biohydrogen: fermenting bacteria release hydrogen from organic substrates, a clean fuel for the future.
- Microbial fuel cells: bacteria oxidising organic waste generate electricity directly, useful alongside sewage treatment.
- Enhanced oil recovery: microbes injected into ageing wells loosen trapped crude and raise output.
Limits
- Food-versus-fuel competition, high cost and low yields of advanced routes, and feedstock collection logistics; R&D, assured offtake and price support are needed.
Microbial fuels can meet only part of the shortage, but a waste-to-energy focus makes them sustainable, decentralised and climate-friendly.
Written by Minimalist IAS from facts checked at source (how we verify) — a little fuller than exam length, so every part of the question is covered; in the hall, keep the structure and trim the detail. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.