3232 Chapter 26 



and dehydrating xylose. Thus, it is possible to produce furfural in a one-stage 

 process in which both hydrolysis and dehydration occur in the reaction vessel. 

 Harris (1978) indicates that the residue from such a process can supply more fuel 

 for heat energy than the process requires. 



26-9 INDUSTRIAL USE OF WOOD ENERGY 



The forest products industry is the fourth largest user of purchased energy in 

 the Nation (U.S. Department of Agriculture, Forest Service 1976). (The petrol- 

 eum, chemical, and primary metals industries are the three largest users.) In 

 1974 the forest products industry purchased about 1.8 quads, or slightly more 

 than 2 percent of the Nation's total energy use (Salo et al. 1978). About 1.3 

 quads were fuel oil and natural gas, energy sources particularly vulnerable to 

 curtailment and interruption. 



The industry also generates such of its own energy from mill wastes and 

 residues. Pulp and paper mills generate the most by burning spent pulping 

 liquors, wood, and bark. Nationally, pulp and paper mills are about 40 percent 

 energy self-sufficient, sawmills about 20 to 40 percent, and plywood and veneer 

 mills, about 50 percent (U.S. Department of Agriculture, Forest Service 1976). 

 At 50 percent, southern pulp and paper mills were more energy self-sufficient in 

 1976 than the national average (table 26-15). However, southern mills also use 

 more energy than any other segment of the pulp and paper industry (table 26-16). 

 The industry is vigorously moving toward a greater degree of energy self- 

 sufficiency. 



Most fuel, purchased and residue, is burned to generate steam for the process 

 requirements of the industry. However, some electricity is also generated in the 

 industry by co-generation. Pulp and paper mills in general produce only about 

 one-half of their electrical needs, but many sawmills could sell excess electricity 

 if the economics were favorable (Pingrey and Waggoner 1978). 



Table 26-15. — Energy use pattern for southern pulp and paper mills^ 



'Data from U.S. Department of Agriculture, Forest Service (1976). 



The forest products industry is in a good position to achieve greater energy 

 self-sufficiency by burning more wood and bark residues to replace or supple- 

 ment purchased fossil fuels (Grantham 1978; Salo et al. 1978; Pingrey and 

 Waggoner 1978; Benemann 1978; Hodman 1978). Such action would also free 



