Blending Isobutanol and Diesel

Blending Isobutanol and Diesel

Syllabus Areas:

GS III - Economy (Energy - Biofuel)

On September 11, Union Transport Minister Nitin Gadkari announced that the Automotive Research Association of India (ARAI) is exploring the blending of isobutanol with diesel.

• Earlier attempts to blend ethanol with diesel were unsuccessful, due to technical challenges.
• This initiative comes within the larger framework of India’s energy transition and the government’s target of achieving net zero emissions by 2070.

Why Isobutanol is Being Considered

• Ethanol vs Isobutanol:
  • Ethanol: surplus availability but not suitable for diesel blending due to low flash point and volatility.
  • Isobutanol: shows better blending compatibility with diesel.
• Advantages of Isobutanol over Ethanol for Diesel Blending:
  • Higher flash point → safer handling and lower fire risk.
  • Blends more easily with diesel, without requiring additional complementary substances for efficiency.
  • Reduces risks of volatility and storage hazards compared to ethanol.

Availability and Surplus Considerations

• Surplus ethanol production in India:
  • More than 50% of requirements for petrol blending already met.
  • Surplus remains even after industrial consumption.
• Challenge: Procurement prices of ethanol (from cane juice/syrup or B-heavy molasses) have remained unchanged since ESY 2022–23, despite 5% increase in FRP of sugarcane.
• Result:
  • Declining economic viability for sugar mills.
  • Risk of surplus sugar build-up in domestic market.
• Opportunity: Isobutanol blending creates a new demand channel for excess sugarcane-based raw material, balancing the sugar-ethanol economy.

Economics of Isobutanol Production

• Feedstock: Can be produced from the same raw materials as ethanol – sugarcane syrup, molasses, grains.
• Production Process:
  • Uses engineered microbes (not conventional yeast) for fermentation under sterile conditions.
  • Produces isobutanol instead of ethanol.
• Infrastructure Requirements:
  • Minimal changes needed in existing sugar refineries.
  • Example: A plant with 150 kilo litres/day capacity → can produce 125 klp/d ethanol + 20 klp/d isobutanol.
  • Only retrofitting of fermentation and distillation tanks required.
• Cost Feasibility: Economically viable due to limited need for new infrastructure.

Technical Concerns and Limitations

1. Cetane Number Issue
   • Cetane number: measures ignition quality of diesel fuel.
   • Isobutanol has a much lower cetane number than diesel.
   • Consequences:
     • Poorer combustion quality.
     • Higher risk of diesel knock (premature or uneven ignition causing noise, reduced power, and engine damage).
   • Solution: Use of additives to restore cetane value (but increases cost).
2. Miscibility Issues
   • Isobutanol and diesel may not mix well to form a homogenous blend.
   • Can be improved by adding biodiesel (from non-edible oils, used cooking oil, or animal fats).
3. Engine Impact
   • Experts caution against blending more than 10% isobutanol with diesel.
   • Higher blends could damage engines and reduce performance.

Potential Benefits if Successful

• Environmental Benefits: Reduction in emissions compared to pure diesel.
• Energy Security: Import substitution → reduces crude oil dependency.
• Agricultural & Industrial Benefits:
  • Utilises surplus sugarcane production.
  • Stabilises ethanol economy and sugar sector finances.
• Innovation: India could become the first country globally to blend isobutanol with diesel.

Future Outlook

• ARAI is conducting pilot studies.
• Timeline: Expected to take ~18 months for results.
• Large-scale adoption will depend on:
  • Engine performance studies across vehicle types.
  • Cost-benefit analysis (additives, retrofitting, price viability).
  • Policy decisions on procurement pricing and blending mandates.

Prelims Questions:

Mains Questions:

• “Isobutanol may emerge as a viable biofuel alternative for blending with diesel in India, but technical and economic challenges remain.” Discuss.
• What are the advantages and limitations of using isobutanol as a blending fuel with diesel compared to ethanol? Examine in the context of India’s energy security and net zero goals.