The Interest of combining an additive with fuel blends

N-butanol is a good additive for mixing diesel with ethanol although the price of n-butanol was higher than that of diesel. From a long-term point of view fossil fuels including diesel will be depleted due to the limited sources; more and more bio fuel including diesel will be gradually used as the alternatives to replace the fossil fuels. It might not be economical to use n- butanol today but it would be in the future.