Partial combustion is one method. In this procedure, biomass is burned in an environment with restricted oxygen. Carbon monoxide and hydrogen are formed instead of carbon dioxide and water. Syngas may also be converted to methanol, a one carbon-alcohol that can be used as a transportation fuel. Because methanol is a liquid, it is easy to store and transport.
Anaerobic digestion is another method for forming gases from biomass.
It uses microorganisms, in the absence of oxygen, to convert organic materials to methane. This method is particularly suitable for animal and human waste. Animal feedlots faced with disposal problems may install microbial gasifiers to convert waste to gaseous fuel used to heat farm buildings or generate electricity. For materials rich in starch and sugar, fermentation is an attractive alternative. Through acid hydrolysis or enzymatic digestion, starch can be extracted and converted to sugars.