Exploring Potential U.S. Switchgrass Production for Lignocellulosic Ethanol (original) (raw)
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Energy crops for ethanol: a processing perspective
2008
Global production of bioethanol for fuel is over 13 billions gal per year. Continued expansion of ethanol production will necessitate developing lignocellulose as an alternative to today’s use of starch and sugar producing crops. Dedicated energy crops are one such option. In the U.S., it has been estimated that enough perennial crops can be grown to supply 9–23 billion gal of ethanol/yr – assuming a yield of 60 gal/ton. However, further research is needed to understand the roles that agronomic practices and genetics play in affecting realizable ethanol yields. Biochemical conversion of biomass following thermo-chemical pretreatment is currently the leading technology for producing ethanol from these feedstocks. We compared a warm season grass (switchgrass), cool season grass (reed canary grass), and legume (alfalfa stems) for sugar production. To introduce further variation in this sample set, each species was harvested at 2 or 3 different maturities. Both species and maturity sign...
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 percent to 27 percent (5.5-30 billion gallons) of present gasoline requirements. Thus, the ethanol requirement for total gasohol use (10 percent 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 gallons 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 gallons of 192º PR ethanol fuel by the year 2000. Fast-growing woody species from silviculture are expected to yield a conservative average of 10 oven-dry tons per acre per year, convertible to 710 gallons of ethanol in a process that has 37 percent 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 United States at present mileage demands. No conflict with food production would be necessary.
Second-generation ethanol: concept, production and challenges
Ecletica Quimica
The use of biological agents for the large-scale production of biofuels has stood out as successful processes for the advancement of science in the world. The growing exploitation of biomass in the agricultural sector and the emergence of new energy sources generated from food industry waste have become attractive and viable due to the potential and variety of possibilities for using different sources of biomass. The present review was carried out through careful bibliographical research in the literature and in scientific journals for the current discussion of concepts, production methodologies and challenges for the energy sector considering second-generation ethanol (2G ethanol). Several 2G ethanol production methodologies have been implemented as a potential low-cost alternative energy production that follows the principles of Green Chemistry.