[Gasification] Biogas from cow dung.

[MMBTUPR at aol.com]

     from          Lewis L. Smith

Yes, it is feasible to produce biogas from cowdung. It has been done many 
times experimentally and commercially and around the world.

The most appropriate technology is called anaerobic digestion and basically 
consists of putting a wet slurry of dung and water in a closed tank and 
allowing three kinds of microbes to split up the molecules. [ The tank should have 
little or no oxygen inside. ]

Since the microbes like to "sit down" while they are "snipping" away, one 
should look into the honeybee type comb structure placed inside its digester by 
the Bacardí Corporation, a rum distillery in Cataño, Puerto Rico.   This 
digester uses distillery slops instead of dung and provides all of the low-pressure 
steam needed by the distillery.

Into every life "a little rain must fall", and so it is with anaerobic 
digestion. 

[1]     The biogas has a low energy density, typically about 40% of that of 
natural gas, so it must be used near to where it is produced. This makes ideal 
for dairies which use adsorption type cooling systems for their milk, as these 
systems require heat to gasify the working fluid of the system. In addition, 
this gas can also be used to power modified diesel-motor powered electric 
generators, again for onsite consumption. The residual slurry can be used as a 
fertilizer for field whose crops will not be fed to human beings or to the same 
cows which produced the dung.

[2]     Digesters frequently generate appreciable amounts of hydrogen 
sulfide, a toxic gas which may have to be filtered out. However, with 
motor-generators, it is generally sufficient to start up and shut down the motor on straight 
butane, so no acid condenses on the cylinder walls.

Hope this is helpful.   

Cordially. ###


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