Q: What part of the tree contributes the most to its density?
My son is doing a science fair project comparing the thermal energy (BTU's) of several species of tree wood that we have collected from around the farm. He will have to describe the trunk anatomy and make a hypothesis as to why some species produce more BTU's than others. Is there a direct correlation between density and stored thermal energy? - Robin
A: Here are several places for him to start. Pick up some key words using these brief reports to find much more info on the physics of heating with wood. Google the terms you are not familiar with.
You are right that every species has its own unique thermal energy potential (BTUs). Usually the harder the wood, the higher the usable energy potential mainly because of more wood per unit volume. But you can't discount other very important factors like green vs. seasoned efficiency and the effects of "coaling" which prolongs heat release in wood burning systems. - SN