Re: GAS-L: Anaerobic digestion - Energy Yields

[Jane Turnbull <jaturnbu@ix.netcom.com>]

Title: Re: GAS-L: Anaerobic digestion - Energy Yields

The dry material in biomass typically comprises 50% carbon with the rest being hydrogen and oxygen in various forms of carbohydrates, such as cellulose.
 
In wet anaerobic conditions bugs convert carbon in cellulose into equal molecular proportions of methane (CH4) and carbon dioxide (CO2). So half of the decomposed carbon ends up in methane.
 

Steve,

Most forms of biomass contain significant amounts of lignin, which is not a carbohydrate and is not digested by natural strains of bacteria. (Lignin makes up the structural component of plants.) Furthermore, the hemicellulose fraction of biomass is also not fully digestible.  Thus,  50% overall digestibility is the limit for most biomass materials.  

Jane Turnbull
Peninsula Energy Partners