Energy, fuels, and chemicals 



3169 



Tissue 



Wood 



Stemwood . 



Branchwood 



Bark 



Stembark . . 



Branchbark . 



Average 



Minimum 



Maxi 



-Percent of unextracted ovendry weight 



0.75 



.94 



7.87 



6.76 



0.43 



(northern red oak 



and yellow-poplar) 



.60 



(sweetbay) 



4.08 



(yellow-poplar) 



4.12 

 (yellow-poplar) 



1.33 

 (hackberry) 



1.45 

 (hackberry) 



12.12 

 (winged elm) 



11.75 

 (winged elm) 



Thus, variation among the species is significant. Even among the 1 1 oak spe- 

 cies, ash content in all components varies significantly with species. For exam- 

 ple, the stem bark of white oak and post oak have about 1 1 percent ash content, 

 while that of scarlet oak has less than half this amount (5.18 percent). 



Mineral analyses of the ash of above-ground wood and bark are shown in table 

 6-19. 



See tables 14-9 and 14-10 for ash and mineral content of wood and bark in 

 stump-root systems of pine-site hardwoods. 



Studies of other species indicate that wood ash is generally high in CaO (50 to 

 60 percent) and high in Na20 and K2O (4 to 7 percent). Stemwood of southern 

 hardwoods has about equal content of K and Ca (about 2,000 ppm of each); bark 

 of these hardwoods has a much higher content of Ca than K. Percentages of ash 

 components probably vary significantly among species and with fuel types, i.e., 

 stems, branches, wood, or bark. Some values for wood and bark are shown in 

 table 26-6, but these values do not represent averages specifically applicable to 

 hardwoods grown among pines. 



Table 26-6. — Chemical composition of ash from bark and wood^~ 



Component 



Southern 

 bark #1 



Southern 

 bark #2 



Oak 

 bark 



Wood"* 



Silicon as Si02 . . . . 

 Aluminum as AI2O3 

 Titanium as Ti02. . . 



Iron as Fe203 



Calcium as CaO. . . . 

 Magnesium as MgO 

 Sodium as Na20 . . . 

 Potassium as K2O . . 

 Sulfur as SO3 



Percent of ovendry weight 



Data from Babcock and Wilcox Company (1972) and personal correspondence with Babcock and 

 Wilcox Company, January 1982. 



Component percentages will vary significantly with wood species and between wood and bark 

 fuels; analytical techniques may not permit summing to 100 percent. 



^Species not known. 



