Characterization of biomass using instruments – Measurement of forest and crop residues - Biomass as Energy Source: Resources, Systems and Applications - page 58

Figure 3.1. Container truck.
Figure 3.2. Side-tipping truck.
Storage will also affect the moisture content. The humidity of the surface area will be affected
by the recent weather. Rain or snow will remain close to the surface during precipitatious weather
while the surface dries in warm and sunny weather. Further, material close to the ground tends
to contain some amount of dirt that is scraped up when the fuel is picked up and loaded in
a truck.
In addition to this, biological activity will cause a degradation of the biomass. Bacteria and
fungi will consume part of the biomass in order to produce water and heat. In the center of the
pile, the moisture content is likely to increase since water is a by-product of the biological activity.
Accordingly, the calorific value decreases as the energy is consumed by the bacteria and fungi.
However, the moisture content in adjacent biomass might decrease because the heat evolved dries
the material. The calorific value of terminal fuel will therefore differ a lot depending on the
storage time and its position in the pile.
The previous examples do not constitute an exclusive list. However, they illustrate some of
the many causes of why the moisture content of a shipment will fluctuate within a large range.