Composition, biomass barks

The impact of extraneous inorganic matter on the analysis cannot be predicted. Most chemical analysis methods have been optimized for bark-free wood that has an ash content of less than 2 percent. These methods may not be applicable to herbaceous materials where structural silica can increase the ash content to more than 15 percent of the dry weight of the biomass. One potential problem with high ash samples is that inorganic materials, depending on their composition, may neutralize the sulfuric acid solutions used in the hydrolysis steps. The affect of pH changes... 

Roy, C., Calve, L., Lu, X., Pakdel, H., and Amen-Chen, C. (1999) Wood Composite Adhesives from Softwood Bark-Derived Vacuum Pyrolysis Oils.In Biomass A Growth Opportunity in Green Energy and blue Added Products. 

Woody biomass is low in ash content, sulphur, chlorine and silica, and the ash itself is dominated by compounds of Ca and K. Biomass fuels from crops are higher in ash content, sulphur, chlorine and silica. The ash is dominated by oxides of Ca, K and Si. The fuels based on the growing parts of trees (bark+debries) show ash compositions between the two extremes, wood and acre crops. Therefore the largest chlorine emissions are expected from energy crops (grasses) and from agricultural by products (straw etc). 

Forest residue is defined as the biomass left in the woods after harvest and includes tree tops, limbs, cull material, and all present and future non-merchantable trees. This differs from mill residue such as bark, edgings, and sawdust, which is often fully utilized as boiler fuel. The amount of residue remaining after harvest will vary according to merchantability standards, method of harvest, and forest stand composition and quality. In a typical hardwood sawlog harvest as much as 50 percent of the potential usable biomass may be left as residue. If the sawlog stand is overmature or of poor quality, additional residue may be left. In contrast, if the stand is whole-tree chipped for pulp material, very little residue will remain. 

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