Energy, fuels, and chemicals 3161 



Summative chemical analyses of stemwood of 18 of the principal pine-site 

 hardwoods are given in table 6-1. Percentages of the components range as 

 follows: 



Component Percent 



Cellulose 33.8-48.7 



Hemicellulose 23.2-37.7 



Lignin 19.1-30.3 



Extractives 1.1-9.6 



Ash .1- 1.3 



100 



Chemical constituents of bark are discussed in section 13-5; mineral contents 

 are summarized, by species, in table 6-19. 



Table 26-3. — Typical ultimate analysis for hardwood species^ 



Wood Bark 



Percent 



Carbon 50.8 51.2 



Oxygen 41.8 37.9 



Hydrogen 6.4 6.0 



Nitrogen .4 .4 



Ash .9 5.2 



'Data from Arola (1976). 



Table 26-4. — Typical proximate analysis for hardwoods^ 

 Component Wood Bark 



Percent 



Volatile matter 77.3 76.7 



Fixed carbon^ 19.4 18.6 



Ash 3.2^ 4.6 



'Data from Arola (1976). 



^Differs from value in ultimate analysis due to different purpose and method of determination. 

 ^The high ash content of the wood was probably due to dirt adhering to the wood residues 

 analyzed. 



Data on ash content of stemwood, stembark, branchwood, and branchbark 

 from 6-inch-diameter pine-site hardwoods of 22 species sampled throughout 

 their southern ranges are presented in table 6-18. 



26-3 DIRECT COMBUSTION 



Today, as in the past, the most common way to use wood and bark for energy 

 is to bum it for heat. In the United States the use of wood for fuel peaked about 

 1 875 and has dramatically declined with the availability of fossil fuels (Corder 

 1973). Internationally, however, about half of all harvested wood is still used for 



