the average hhv of biomass fuel samples are given in table 2. the hhv of extractive-free samples reflect the hhv of lignin relative to those of cellulose and hemicellulose. it has been reported that cellulose and hemicelluloses have a hhv of 18.60 kj , whereas lignin has a hhv of 23.26 to 25.58 kj. as discussed by baker, the hhv reported for a given species are only for the samples tested and not the entire population of the species. the hhv of a lignocellulosic fuel is a function of its lignin content. using linear regression analysis, the hhv can be correlated with the chemical composition