Wood can be used in a variety of different forms, but to make best use of it it must be processed to the optimum form for the equipment in use.
Freshly harvested, or "green" wood typically has a moisture content of around 50-60% (wet basis). Although some equipment is specifically designed to be able to burn green fuel, most wood chip boilers require a moisture content of around 30-35%, while log stoves and boilers typically require 15-25% moisture content
In order to be able to automate the fuel feed for a biomass boiler, the fuel needs to be converted into a form in which it can be made to flow from a bulk fuel store into the boiler, typically using a screw auger. This is usually done by chipping, but it is critical that the chips are of regular size, without excessive "fines" (dust) or long slivers, that can cause blockages