3154 Chapter 26 



technological gaps prevent us from fully using this potential now. Extensive 

 research and development are underway to find methods for converting coal into 

 fuels that are economically acceptable and environmentally clean. Coal usage is 

 expected to more than double in quantity and to provide 27 percent of our energy 

 base in 1990 as compared to 18 percent in 1977. 



Among potential sources, one that has generated considerable interest — 

 mainly because it is renewable — is biomass, that is, living matter. For example, 

 the U.S. Department of Energy and others are assessing the technical and 

 economic feasibility of using intensively managed, short-rotation tree farms as a 

 source of energy for the future (Inman et al. 1977; U.S. Department Energy 

 1979ab; Dawson et al. 1978; Inman and Salo 1978; Krinard et al. 1979). Malac 

 and Heeren (1979) provided an economic evaluation of intensive hardwood 

 plantation management yielding 50 percent more volume at one-third the cost of 

 natural regeneration. 



Essentially biomass is a form of stored solar energy. Green plants use sunlight 

 as energy in photosynthesis to convert carbon dioxide (CO2) and water (H2O) to 

 higher energy carbohydrates (CH20)n and oxygen (O2), together with other 

 compounds such as hydrocarbons, fats, and proteins in the process (Calvin 

 1976; Bassham 1980). Overall photosynthetic conversion efficiency for plants 

 in the temperate zone ranges from 0. 1 to 1 percent of the total available sunlight. 

 Calvin (1976) envisions that eventually synthetic systems will be developed to 

 simulate plant photosynthesis in producing renewable fuel. 



Estimates of the annual storage of solar energy in the U.S. biomass system are 

 as high as 80 quads a year (Falkehag 1977). The U.S. Department of Energy 

 estimates 7 to 8 quads are produced annually in our forests (Del Gobbo 1978). 

 Standing available forests contribute about 300 quads to the proven reserves of 

 energy in the U.S. (fig. 26-2). 



The equivalent of about 4 quads of our forests are harvested annually for 

 lumber and paper products. These products are more valuable than fuel. Howev- 

 er, the residues from these resources can be, and many of them are, utilized for 

 energy. 



The forest products industry already produces (1983) about 1.5 quads of 

 energy from its residues. In the near term, an additional 0.5 to 1 .0 quad could be 

 realized from combined forestry and agricultural residues. The projected contri- 

 bution of biomass to our national energy requirements by the year 2000 ranges 

 from 3 to 8 quads. (Del Gobbo 1978; Zerbe 1977). To aid in achieving this goal, 

 the Department of Energy has established a Fuels from Biomass Program. Its 

 objective is to develop technologies for the preparation, harvest, and conversion 

 of renewable biomass into clean fuels, petrochemical substitutes, and other 

 energy-intensive products (Del Gobbo 1978). 



In the South, hardwoods growing on pine sites are a virtually unused source of 

 biomass. Over the years attempts to use these hardwoods have been thwarted by 

 the diversity of species, scattered occurrence, smallness and shortness of boles, 

 branchiness of crowns, and prevalence of knots. Therefore, most of these 

 hardwoods are destroyed during site prepartion for pine — a destruction that is 

 wasteful and costly (perhaps $100 per acre in 1981). Economic uses for these 



