Ethanol from crop waste, corn, and sugar beet etc is currently added in small percentages to petrol to reduce fossil fuel use. It has lower energy density than petrol (lower mileage), is corrosive to engines (cannot be used in high concentrations), and it absorbs water from the atmosphere which can cause engine problems. 

Butanol is a heavier alcohol without any of these problems, but is more expensive to process (ferment and distill) from crops than ethanol. New research has led to new families of catalysts which will enable existing ethanol plants to output butanol by adding one reactive conversion step at the end of their processing.

This brings us one step closer to butanol (renewable fuel biobutanol) being commercially viable as the biofuel of the future to replace petrol.

Take a look here at our new article Butanol vs Ethanol Fuel of the Future for more information.