John D. Ferchak

Utilization of biomass in the U.S. for the production of ethanol fuel as a gasoline replacement—I terrestrial resource potential

Abstract With relatively minor adjustments in the agricultural sector, large additional amounts of starch derived from feed corn, surplus and distressed grain, and set-aside land could presently be used for ethanol production. The quantity of ethanol that could be produced would be sufficient to replace anywhere from 5 to 27 per cent (5.5–30 billion gallons) of present gasoline requirements. Thus, the ethanol requirement for total gasohol use (10 per cent) in the U.S. could be met in the short period of time required for facility construction with no evident impact on food production. Increased supplies of ethanol will make feasible the introduction of ethanol fueled engines. High-yield sugar crops planted on new acreage could provide an additional 10 billion gal. of ethanol by the year 2000; conversion of the waste biomass from this crop to ethanol could also add substantially to this amount. Utilization of novel cellulose conversion technology can provide fermentable sugars from municipal wastes, agricultural and forest wastes, and ultimately, highly productive silvicultural operations. The wastes alone could yield over 36 billion gal. of 192° PR ethanol-fuel by the year 2000. Fast-growing woody species from silviculture are expected to yield a conservative average of 10 over-dry tons per acre per yr, convertible to 710 gal. of ethanol in a process that has 37 per cent yield. Advantages over sugar/starch crops include year-round harvesting, and use of marginal acreage. Commercial forest land presently suitable for silviculture is about 100 million acres in large tracts plus 200 million acres in small private tracts. The potential additional yield of ethanol from lignocellulosic biomass appears to be well in excess of liquid fuel requirements of an enhanced efficiency transport sector in the U.S. at present mileage demands. No conflict with food production would be necessary.

Utilization of biomass in the U.S. for the production of ethanol fuel as a gasoline replacement—II Energy requirements, with emphasis on lignocellulosic conversion

Abstract Silvicultural operation is estimated to have a liquid fuel requirement of 77 gal. of 192° PR ethanol fuel (or 46 gal. of diesel fuel) per acre/yr, to produce 10 oven-dry tons per acre/yr of wood chips for local conversion. The gross ethanol yeild of the conversion facility is 710 gal. of 192° PR per acre/yr. Enzymatic cellulose conversion processes are in the development stage and rapidly moving to commercialization. Novel approaches to pretreatment and product separation promise to substantially reduce present energy requirements. Optimized conversion processes can generate co-products (lignin, extractives and biogas) in quantities sufficient to allow process energy self-sufficiency if necessary. Alternatively, co-products may find strong demand for use as chemical feedstocks. Process energy may then be met by low-quality fossil fuel such as coal and peat, or by site-optimized, non-polluting sources such as geothermal energy or direct solar conversion. CO 2 and low-temperature heat are by-products that could represent a positive energy input to an adjoining greenhouse facility for high yield foodstuff production. The liquid fuel input critical to the overall process is found to be about one-ninth of the output.