Ash Content

Ash from biomass comes from the minerals present in the structure of the plant and any soil contamination. Characterization of ash by elemental analysis and fusion temperatures is important when selecting biomass fuels because it provides information on how much ash will be generated requiring disposal and indicates the potential for slagging and fouling of burners and boilers (Riedl and Obernberger 1996). When wood is combusted as the only fuel, ash fusion is not usually a problem since the combustion temperatures are likely to be low. However, when biomass is co-fired with coal, combustion temperatures are considerably higher and may reach a level where slagging could occur (Misra et al. 1993).

Ash management presents both a problem and an opportunity. Removal of ash from the furnace and disposal in landfill areas incurs costs for power plants. However, if ash is recycled in the forest or agricultural ecosystems or used to reclaim mine spoils, depletion of plant nutrients, other than nitrogen, and acidification associated with intensive biomass removal is radically reduced.

Sugar and Ash Composition of Feedstocks