What is the calorific value of sawdust?

Answer 1

The "calorific value" (assuming you mean heat of combustion) of sawdust varies somewhat depending on the kind of wood the sawdust came from. It is also influenced by the amount of moisture in the sawdust - if the sawdust is not dry, some of the heat is absorbed to heat up the water and evaporate it instead of being given off as heat. The heating value of sawdust from softwoods (like pine) is typically about 20-22 MJ kg-1 and of hardwoods (like oak and maple) about 19-21 MJ kg-1. Note that despite the similarities of these ranges, there are plenty of woods that will yield higher and lower values; for example tests on poplar trees have a range of values of 19·49 MJ kg-1.