Fuel pellets are a pretty refined technology in their own right. Many sources of raw biomass can be made into pellets, including timber industry by-products and recycled timber. The pellets are pressed in controlled conditions to ensure that they are dry enough to burn with exceptional efficiency.
What's more, dry pellets flow smoothly from the boiler's hopper, through the system to the crucible where they are incinerated.
Fuel pellet distributors can certify that their products are of a high calorific value and low moisture content (to comply with European standard EN 14961).
Once in your possession it is important that you keep your fuel dry. Whether it is held in a hopper, or stored in sealed packaging. This will ensure that your system will provide the power at the efficiencies that you expect.