This study aims to derive a qualitative model for energy requirements of
the wood chipping process. A relationship is shown between energy
requirements and properties of biomass, which is a quite variable
material.The relationship between comminution machinery and energy which
is necessary for the process is highlighted. The derivation of the model
is focused on chipping, but it is generally possible to make it
available for both different types of biomass (f. ex. agricultural
residues)and different types of comminution machinery (f. ex.
hammermills) by using different material properties adjusted to the
machinery mechanics. The properties which are used in the derivation are
meant to be easy to measure. Furthermore, the model is meant to be used
as a base for a quantitative model that, thanks to measurements taken
from real comminution machinery and thanks to using wood with known
properties, could answer two important questions: - Would hypothetical
changes in the desired size of output material increase the total system
efficiency, taking into consideration the lowest efficiency of the
combustion process (e.g., higher amounts of unburned fuel)? -
Considering the energy used for the process, how can comminution as an
operation in the biofuel supply chain be optimised? Answers for the
above questions could highlight new possibilities in terms of further
energy savings and a maximising of the energy efficiency of the
bioenergy sector. Furthermore, the results could motivate optimized
choices of comminution machinery for the biofuel supply chain as well as
for other applications. Another important feature of this study is its
unique holistic point of view that takes into consideration aspects from
the fields of mechanics, material sciences and natural sciences to
deliver the full picture to the reader.
