In the search for next generation bio-fuels, butanol produced by fermentation of agricultural products and wastes has emerged as a promising hope for the alternative fuel in future.

Limited experiments suggest that butanol is an alternative fuel for spark ignition (SI) engines. But cost competitive production technologies have to be put in place and detailed material compatibility studies on the effect on human health have to be done before it can be used as an alternative transportation fuel on a commercial scale.

Butanol is a four carbon alcohol. Recently, butanol produced by fermentation, know as bio-butanol  can be mixed in higher ratios with gasoline or diesel without phase separation and for use in existing cars without the need for retrofit as the air-fuel ratio and energy content are closer to that of gasoline as the air-fuel  ratio and energy content are closer to that of gasoline. 

Butanol could gradually replace gasoline as well as diesel due to its high energy content, miscibility, better combustion characteristics, low volatility and other positive qualities, experts say

According to Mritunjay Kumar Shukla of the Dehradun-based Indian Institute of Petroleum kinematic viscosity of butanol is several times higher than that of gasoline and about as viscous as high quality diesel fuel. Latent heat of vapourisation of butanol is less than half of that of ethanol; an engine running on butanol should be easier to start in cold weather than one running on ethanol.

Its Stoichometric A/F ratio is 11.2 which allows butanol to function in a standard engine where gasoline is used. The Stoichometric A/F ratio of gasoline is 14.7 while that of ethanol is 9. Butanol’s energy content is about 105,000 Btu per US gallon while that of gasoline is about 114,000 Btu per US gallon. In effect butanol has about 92% of the energy of gasoline. Shukla was recently in Delhi on the occasion of the 6th International Bio-fuel Conference organized by Winrock International India (WII).

Additionally as butanol has a very low vapour pressure point (RVP) of o.3 and a high flash point (FP) of 37 degree Celsius it is very safe fuel to use in high temperatures. Consequently butanol is a very versatile fuel and fuel extender in both gas