This is a time-consuming, somewhat tedious approach, but it is also a necessary means of adapting
values from pertinent literature to unknown regions. The method is rather inaccurate if no total-
solids measuring is included. Direct measurement can, however, provide indication of seasonal or
fodder-related variance if sufficiently long series of measurements are conducted.
Determining the biomass supply via pertinent-literature data
(cf. tables 3.2/3.3)
According to this method, the biomass incidence can be determined at once on the basis of the
livestock inventory. Data concerning how much manure is produced by different species and per
liveweight of the livestock unit are considered preferable.
Dung yield = liveweight (kg) x no. of animals x specific quantity of excrements (in % of liveweight
per day, in the form of moist mass, TS or VS).
Determining the biomass incidence via regional reference data
This approach leads to relatively accurate information, as long as other biogas plants are already in
operation within the area in question.
Determining biomass incidence via user survey
This approach is necessary if green matter is to be included as substrate.
It should be kept in mind that the various methods of calculation can yield quite disparate results
that not only require averaging by the planner, but which are also subject to seasonal variation.
The biomass supply should be divided into two categories:
Category 1: quick and easy to procure,
Category 2: procurement difficult, involving a substantial amount of extra work.
Table 4.2: Outline for determining biomass incidence (Source: OEKOTOP)
Source of biomass
Animal dung
Number of cattle: ............
Dung yield per head
Amount collected ...........
Dung yield from cattle
Number of pigs: ..............
Dung yield per pig
Amount collected: ...........
Dung yield from pigs
Sheep, camels, horses etc.................
Green matter
1. grass, etc.
2....................................
Night soil
Number of persons: ..................
Dung yield from night soil
Total biomass incidence
Moist weight
(kg/d)
TS/VS weight
(kg/d)
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
.......
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