Isobutanol-Diesel Blending for Biofuel: Pros and Cons

Blending Isobutanol with Diesel: Feasibility and Challenges

1. What is Isobutanol?

Isobutanol is an alcohol-based compound with inflammable properties and is commonly used as a solvent. It is now being studied as a biofuel alternative, particularly for blending with diesel.

2. Why is Ethanol Not Preferred for Diesel?

Ethanol blends well with petrol but not with diesel. It has a lower flash point, making it volatile and unsuitable for diesel engines. Attempts at blending ethanol with diesel have failed in India.

3. Why is Isobutanol Considered Better?

• Higher flash point → Safer than ethanol in diesel engines.
• Better blending quality → Forms a more stable mixture with diesel.
• Availability → Can be produced from sugarcane, molasses, and grains.

4. How is Isobutanol Produced?

It can be produced by fermenting biomass (sugarcane, molasses, grains) using engineered microbes. However, infrastructure changes like fermentation tanks and separation units are required to scale production.

5. Economic Viability

India already has ethanol surpluses, and sugar mills are geared towards ethanol production. To encourage isobutanol, sugar manufacturers demand a fair price mechanism similar to ethanol pricing. Without government support, mills may not shift due to higher costs and possible imbalances in domestic markets.

6. Challenges

• Lower cetane number: Can reduce engine efficiency.
• Infrastructure changes: Retrofitting plants adds extra costs.
• Knocking risk: Poor blending quality may damage engines.
• Supply-demand mismatch: India already faces ethanol overproduction.

7. Way Forward

• Government support through pricing reforms and subsidies.
• Pilot projects (around 18 months) to test large-scale feasibility.
• Focused research on improving fuel properties and reducing risks like knocking.

Synopsis

Isobutanol is emerging as a potential alternative to ethanol for blending with diesel in India. Unlike ethanol, which is unstable in diesel, isobutanol offers a higher flash point and better blending stability. It can be produced from sugarcane and grains, but economic and infrastructural challenges remain. Issues include lower engine efficiency, high production costs, and surplus ethanol. Pilot projects over the next 18 months will assess its viability, with government support vital for successful adoption.