Biofuels: Bioethanol, Biodiesel and Biogas from Biomass
Science & Technology › Biotechnology – Applications · Topic 11.10
Biofuels are fuels made from biomass, which is living or recently living plant, animal or microbial material. The main types are bioethanol, an alcohol made by fermenting sugar or starch, biodiesel, made from vegetable oil or fat by a reaction called transesterification, and biogas, a mixture of methane and carbon dioxide made by anaerobic digestion of organic waste. Biofuels are grouped into generations: first generation from food crops such as sugarcane and maize, second generation from agricultural residue and waste, third generation from algae, and fourth generation from engineered organisms. India's National Policy on Biofuels, 2018, was amended in 2022 to advance the target of 20 per cent ethanol blending in petrol to 2025-26.
5 min read · UPSC Prelims · Science & Technology · Biotechnology – Applications
At a Glance
- Ethanol Fermentation of sugar or starch
- Biodiesel Oil plus alcohol, transesterification
- Biogas Anaerobic digestion
- Policy National Policy on Biofuels, 2018
- Blending goal 20 per cent ethanol by 2025-26
- Exam link UPSC Prelims, Science & Technology: Biotechnology – Applications
Where Does It Fit?
This topic follows biosafety protocols. It returns to the applications of biotechnology, now in energy, where microbes and enzymes turn plant material into fuel. Previous topic: Biosafety Protocols. Next topic: Hydrogen Generation as a Fuel Source.
What Are the Types and Generations of Biofuels?
| Biofuel | Source and features |
|---|---|
| Bioethanol | Made by yeast fermentation of sugarcane juice, molasses, maize or grain. Blended with petrol to reduce imports and emissions |
| Biodiesel | Made from vegetable oils, used cooking oil or animal fat by transesterification with methanol. Blended with diesel |
| Biogas | About 55 to 65 per cent methane. Made from cattle dung, food waste and crop residue. Purified biogas is compressed biogas |
| First generation | From food crops such as sugarcane, maize and edible oils. Raises food versus fuel concerns |
| Second generation | From non-food biomass such as straw, bagasse and municipal waste, using enzymes to break cellulose |
| Third generation | From algae, which grow fast and need little land |
| Fourth generation | From organisms engineered to capture carbon dioxide and make fuel directly |
What Are the Indian Policies and Programmes?
- National Policy on Biofuels, 2018: approved in 2018, it allows ethanol from sugarcane juice, sugar, grain, damaged crops and surplus rice, and promotes second generation fuels
- Ethanol blending target: the 2022 amendment moved the target of 20 per cent blending to 2025-26. India reached about 20 per cent blending in 2025. Check the latest figure
- Pradhan Mantri JI-VAN Yojana: 2019 scheme for financial support to second generation ethanol plants
- SATAT: Sustainable Alternative Towards Affordable Transportation, 2018, for compressed biogas plants
- GOBARdhan: converts cattle dung and waste into biogas, as in Bio-Composting and Carbon Capture Techniques
- Biodiesel programme: blending of biodiesel from used cooking oil through the RUCO initiative of the food regulator
- Global Biofuels Alliance: launched at the G20 summit in New Delhi in September 2023, with India as a founding member
- E100 and flex fuel vehicles: vehicles that run on blends up to 100 per cent ethanol are being promoted
What Else Should You Remember?
- Transesterification: a chemical reaction in which oil reacts with alcohol using a catalyst to give biodiesel and glycerol
- Fermentation of ethanol: yeast converts sugar to ethanol and carbon dioxide without oxygen, as in Bioprocess and Fermentation Technology
- Jatropha and Pongamia: non-edible oil seeds promoted for biodiesel, though yields and economics have been poor
- Lignocellulosic ethanol: the first 2G plant of India at Panipat uses rice straw as feed, an example of crop residue use, as in India’s First Biomass-to-Ethanol Plant and Its Commercialization
- Benefits: lower oil imports, cleaner burning, farmers income and use of waste
- Concerns: use of food crops, water use for sugarcane, land change and need for engine compatibility
- Carbon neutral claim: the carbon dioxide released was taken from the air by the plant, but farming and processing add emissions
- Ethanol procurement price: oil marketing companies buy ethanol at prices set by the Government
- Food security: rules limit the use of food grains, and the Government has at times restricted ethanol from sugarcane juice or allowed rice from surplus stocks
- Compressed biogas: biogas cleaned to remove carbon dioxide and hydrogen sulphide, used as vehicle fuel
- Sustainable aviation fuel: biofuels from oils and waste are blended in jet fuel, and India has set targets for later years
- Link: fuel made from hydrogen is covered in Hydrogen Generation as a Fuel Source
- Energy content: ethanol has lower energy per litre than petrol, so vehicles may give slightly lower mileage on high blends unless engines are adapted
Why Does It Matter for the Exam?
- Types and processes: transesterification and fermentation
- Generations: first to fourth with examples
- Schemes: JI-VAN, SATAT, GOBARdhan
- Current affairs link: ethanol blending progress and Global Biofuels Alliance
- Common errors: saying biodiesel is made by fermentation or that biogas is mainly carbon dioxide
As an analytical point, biofuels cut oil imports and use farm waste, but the food and water costs must be watched. Second generation fuels from residue offer a better balance and also reduce stubble burning.
Why Is This Topic Important?
- Types Three fuels
- Policy Blending targets
- Balance Food versus fuel
What Came Next?
The next topic covers hydrogen as a fuel and the role of biology in making it. Next topic: Hydrogen Generation as a Fuel Source.
Key People and Terms
- Biomass Plant or animal material
- Blending Mixing with petrol or diesel
- Lignocellulose Woody plant material
- Glycerol Biodiesel by product
- Compressed biogas Purified methane
- 2G ethanol Ethanol from residue
Exam Corner
Points to Remember
- Biodiesel: transesterification.
- Biofuel policy: 2018, amended 2022.
- JI-VAN Yojana: 2019.
- Global Biofuels Alliance: 2023.
- Biogas is mainly methane.
Do Not Confuse With
- Bioethanol and biodiesel Fermentation alcohol versus oil ester
- Biogas and compressed biogas Raw gas versus purified fuel
- First and second generation Food crops versus residue
Memory Hook
Ferment for ethanol, esterify for diesel, digest for gas; first from food, second from straw.
Mains Angle
Questions ask about types, policy and trade-offs. These points help.
- Benefits Imports, farmers, climate
- Concerns Food and water
- Way Second generation
A Question You May Face
An original practice question, not a past paper question.
“Discuss the potential of biofuels in India’s energy transition and the concerns associated with their expansion.”
How to Answer
- Types Ethanol, biodiesel, biogas.
- Policy 2018 policy, targets.
- Concerns Food, water.
- Way 2G and waste.
GS Relevance
Frequently Asked Questions
What are biofuels?
Biofuels are fuels made from biomass such as crops, crop residue, used cooking oil and organic waste. The main types are bioethanol made by fermentation, biodiesel made by transesterification of oils, and biogas made by anaerobic digestion. They can replace part of the petrol and diesel used in vehicles and reduce oil imports.
What is the National Policy on Biofuels, 2018?
The National Policy on Biofuels, 2018 is India's framework to promote ethanol, biodiesel and biogas. It widened the raw materials for ethanol to include sugarcane juice, grain and damaged crops, promoted second generation fuels, and was amended in 2022 to bring the target of 20 per cent ethanol blending in petrol forward to 2025-26.
What is transesterification?
Transesterification is the chemical reaction used to make biodiesel, in which vegetable oil or animal fat reacts with an alcohol such as methanol in the presence of a catalyst. The reaction produces fatty acid methyl esters, which form biodiesel, and glycerol as a by product.
What is second generation ethanol?
Second generation or 2G ethanol is made from non-food biomass such as rice straw, bagasse and other agricultural residue. Enzymes first break down the cellulose to sugars, which yeast then ferments to ethanol. It avoids competition with food and helps to use residue that would otherwise be burnt in fields.
What is the Global Biofuels Alliance?
The Global Biofuels Alliance is an initiative launched by India at the G20 Summit in New Delhi in September 2023 to promote cooperation and trade in biofuels. Brazil, the United States and many other countries joined as members or partners, with the aim of speeding up the adoption of sustainable biofuels worldwide.
PYQ Practice — Statement Analysis
1 Biodiesel is produced by the process of transesterification.
Oil reacts with alcohol.
2 Biogas consists mainly of carbon dioxide.
It is mainly methane.
3 The Pradhan Mantri JI-VAN Yojana supports second generation ethanol.
Launched in 2019.
4 Third generation biofuels are made from algae.
Fast growing and land saving.
Past Mains Questions on This Topic
This topic comes under Biotechnology – Applications. UPSC Mains questions asked on the matching syllabus topic, year-wise with marks:
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