II.
UPEI Department of Engineering
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starting point for considering possible material that would be effective if added to a farm
digester. The final column in the table labeled “potential” is our simple estimate of the prospect
for this co-substrate based on the other factors.
Feedstock
Reliability
of source
Energy
content
Cost
Potential
Diseased grain
low
medium
Low
low
Fish plant waste
medium
high
low
high
Municipal sewage
high
high
low
high
Municipal solid waste
high
medium
low
high
Potato culls
medium
high
medium
medium
Potato processing waste high
medium
low
high
Sea Lettuce
high
medium
low
high
Straw
medium
medium
medium
medium
Wood processing waste high
medium
high
low
It is important to recognize that, if on-farm biogas systems are feasible for a small farm, then
they will be installed by farmers as fuel costs and environmental pressures continue to grow. If
many farms install on-site digestion, and they are all sized for large co-substrate supplies, the
availability of the co-substrate will become limited. Thus, it is important that we consider the
potential of a small digester system that will operate only on waste from the farm.
While larger
systems that import organic waste may be attractive, they cannot be a solution that will work on
every farm.
