Effect of Lignin Content and Extractives on the Higher Heating Value of Wood

As part of a study of the charring rate of wood, I determined the higher heating values (gross heat of combustion) and the chemical composition of samples from four hardwoods and four softwoods. The higher heating value of wood was correlated with lignin and extractive contents. There was a highly significant linear correlation between the higher heating value of the extractive-free wood and lignin content. Equations are presented that can be used to determine the higher heating value of extractive-free wood when the Klason lignin content is known. The equations should be useful to those interested in using a variety of species of wood as fuel