Is it feasible to blend isobutanol and diesel?, Pg 13.

Key Highlights:

• Isobutanol blends better with diesel than ethanol, with higher flash point and lower volatility.
• Produced from sugarcane syrup, molasses, grains via fermentation by engineered microbes.
• ISMA claims ethanol supply is already surplus; blending isobutanol can absorb excess production.
• Sugar industry demands price revision of ethanol procurement due to rising cane costs.
• Concerns: low cetane number, miscibility issues with diesel, potential engine knock.
• Pilot project under ARAI to take ~18 months; India could be first to adopt this blend.

Detailed Insights:

• Technical viability: Isobutanol–diesel blend requires fewer additives than ethanol–diesel; miscibility issues may be resolved using biodiesel as stabiliser.
• Combustion quality: Low cetane number reduces ignition efficiency; may be improved with additives, adding costs.
• Safety factor: Higher flash point than ethanol makes isobutanol safer for blending with diesel.
• Industrial feasibility: Existing sugar refineries can retrofit fermentation & distillation units to produce 125 klp/d ethanol + 20 klp/d isobutanol.
• Economic dimension: Surplus ethanol and stagnant procurement prices risk sugar glut; isobutanol blending offers an alternate revenue stream.
• Environmental & strategic value: Supports import substitution, reduces emissions, aids in net-zero 2070 goal.

Concepts Involved:

• Flash Point: Lowest temperature at which a fuel produces vapours that can ignite; higher flash point = safer fuel.
• Cetane Number: Indicator of diesel fuel’s ignition quality; low value risks knocking and inefficient combustion.
• Knocking: Premature/uneven combustion causing reduced power and engine damage.
• Miscibility: Ability of two substances to form a uniform mixture; biodiesel may aid miscibility of isobutanol–diesel blends.