In the region nearby my Institute biomass brequetting and their use as solid fuel is common. the common problem faced is incomplete combustion and due to that excessive smoke formation. to rectify this problem few industries have made provision of addition of excess air by force draft into combustion chamber.
If I am getting your question right, you want to use briquets as feedstock for producing biofuels and not for combustion.
For this, sawdust as such is to be used not after briquetting. As compactness will affect the bioconversion and further processing dueto highly ordered structure and less surface area.
I wish to use sawdust briquette in a boiler for combustion purpose. So I would like to know what are all the problems that are faced when using it in a boiler!