The energy content of fuel is normally expressed in British thermal units (BTUs). Energy content of wood is greatly affected by the moisture content and weight of the wood. For example, hardwood and softwood at 50% moisture will have about 4,700 BTU/lb, whereas the same wood at 20% moisture will contain about 6,200 BTU/lb. Hardwood has about twice the weight as softwood and therefore twice the heat content. The same is true with wood chips that contain about 4,000 BTU/lb green (50% moisture content) and 7,400 BTU/lb dry (10% moisture content).
For more information: Wood Energy for Greenhouses.
Contributor: Vern Grubinger, University of Vermont
