Energy, fuels, and chemicals 3155 



hardwoods would be desirable and several utilization schemes have been pro- 

 posed (Goldstein et al. 1978; Koch 1978, 1982). In the energy self-sufficient 

 Koch approach featuring tree pullers, swathe-felling mobile chippers, and shap- 

 ing-lathe headrigs to make diverse products including structural flakeboard, 

 over 50 percent of complete-tree biomass of all species could be recovered as 

 solid wood products. In the Goldstein et al. approach, entire hardwood trees are 

 chipped in the woods. Such chips can be used for fuel, production of chemicals, 

 or for fiberboard. 



Chapter 16 reviews methods for harvesting hardwoods growing among south- 

 em pines; many of the methods discussed are appropriate for energy wood. 

 Also, sections 28-7 and 28-9 analyze the economic feasibility of several systems 

 of harvesting pine-site hardwoods for energy. 



Sections that follow summarize the potential of using the pine-site hard- 

 woods, or their residues from manufacturing processes, as a source for energy, 

 fuels and chemicals. Conversion processes that are available or near at hand are 

 described, and potential uses and economics of the conversion products are 

 discussed. 



In gaining a perspective of the potential for converting wood to heat energy, 

 fuels, and chemicals, it is useful to summarize conversion efficiencies by major 

 processes (table 26-1). Maximum energy recovery is attained by combustion, 

 with recovery by other processes ranging downward to 25 percent or lower. For 

 example, boilers burning green hardwoods to produce steam may be about 63 

 percent efficient, but overall energy recovered by converting green hardwood to 

 steam and then to electrical energy may be only 25 percent. Interpretation of the 

 Btu yields shown in table 26- 1 also requires knowledge of the values of different 

 products; e.g., a Btu in the form of heat energy (hot combustion gas) has 

 significantly less market value than a Btu of pipeline-grade gaseous fuel, a Btu 

 of ethanol liquid fuel, or a Btu of electrical energy. 



These energy recovery data require considerable interpretation, and will be 

 discussed in more detail in following sections. 



