[Stoves] Composting at 70 deg C ?

[ajheggie at gmail.com]

On Monday 30 May 2011 17:02:54 Crispin Pemberton-Pigott wrote:
> Dear Andrew
>
> What is the CH4 to CO2 ratio from the biogas digesters, roughly?

 Roughly 2:1 but it must be dependant on feedstock. The bacteria only 
convert the volatile solids, I'm not sure of the definition of these but 
basically sugars and lipids ( plant oils and their derivatives). With a 
good feedstock like whole crop maize these will make up to 30% of the 
mass. Often it appears necessary to dilute lipids with carbohydrate 
feedstocks to maintain steady production and preventing the digester 
pickling its contents.

Dr Karve can probably say more as I've only been close to one digester in 
a dairy which feeds power to the grid via a spark converted Rolls Royce 
diesel engine. These units can be very sophisticated and convert H2S into 
H2 and flowers of sulphur which goes back to the land. This increases 
calorific value but mostly save corrosion damage in the engine.

The chap who owns it did his Phd thesis on tea drying in Kenya using the 
waterwide gasifier.

AJH