Here's a chart comparing the pros and cons of different biofuels, to help decide which fuel to use.

Wood gas or Producer gas is a very old form of fuel that is easy to produce and use. It consists of partially combusting biomass, and then burning the smoke and gas as a fuel.

Butanol is a higher energy alcohol than ethanol (105 kBtu vs 70 kBtu per gallon), making it an attractive alternative to ethanol. But, it also has some disadvantages.