Internal energy use of digesters.

["Andre de Boer (Work)" <A.de.Boer@Novem.NL>]

I have seen some ideas about/concepts of manure digesters, working
thermophilically using a NH4 stripper and osmose to seperated the digestate.

My question is about the own use of the digester, that quantity seems me to
be rather high. First some data (units per year, dot is used as
'thousand-separator, not as a decimal-sign.

Capacity: 36.000 ton (pigslurry).
Estimated energy capacity of the biogas: 33.600 GJ, going into a gasmotor
* Electric Power Production (EPP): 11.760 GJ (=35% = 3.267 MWh)
* Heat Production (HP): 21.268 GJ (=62%)

Estimated internal use:
* Electric Power: 4.882 GJ (=1.356 MWh)
* Heat: 13.076 GJ

So:
* 41% of the electricity is used for own, internal use
* 62% of the heat is used for own, internal use
-> all together(heat+power): the digestor uses 17.958 of the 33.600 GJ,
   being > 53%!

This percentage is high.
Q: Who can give me some data on internal energy use of slurry-digesters of
this type. What are characteristical energy uses for the digester and for
the seperator?

Andre de Boer
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