2.3. Conclusions
Due to the low bulk densities of most agricultural residues,
densification may be important for their transportation,
storage and firing. In order to maintain low fuel
costs of the residues, it is more economical to use it close
to the point of generation with only limited transportation
and storage costs involved. In such cases, densification
would only be required if it will enable easier feeding and
a more efficient combustion process. The decision to densify
would then depend on the type of residues and the local
situation. For example, straw and rice husks, with bulk
densities of 32–64, and 122 kg/m3, respectively, are more
problematic to handle than woody residues such as coffee
husks and coconut shells which have slightly higher bulk
densities (e.g. coffee husks—180 kg/m3) [4,19]. For firing
purposes, straw must at least be baled. Alternatively, straw
can be milled and fed into the furnace pneumatically. Rice