Ethanol from biomass

Because oil and gas ate not renewable resources, at some point in time alternative feedstocks will become attractive however, this point appears to be fat in the future. Of the alternatives, only biomass is a renewable resource (see Fuels frombiomass). The only chemical produced from biomass in commercial quantities at the present time is ethanol by fermentation. The cost of ethanol from biomass is not yet competitive with synthetically produced ethanol from ethylene. Ethanol (qv) can be converted into a number of petrochemical derivatives and could become a significant source. 

Considering the full production cycle, methanol from biomass emits less carbon dioxide than ethanol from biomass. This is because short rotation forestry, the feedstocks of methanol, requires the use of less fertilizer... 

Currently, ethanol is produced from sugar beets and from molasses. A typical yield is 72.5 liters of ethanol per ton of sugar cane. Modem crops yield 60 tons of sugar cane per hector of land. Production of ethanol from biomass is one way to reduce both the consumption of erode oil and environmental pollution. Domestic production and use of ethanol for fuel can decrease dependence on foreign oil, reduce trade deficits, create jobs in rural areas, reduce air pollution, and reduce global climate change carbon dioxide build-up. 

Acknowledgments. This work was funded by the Ethanol from Biomass Program of the DOE Biofuels Systems Division. 

We should also try to achieve economy of scale, which would reduce unit cost considerably. Based on plantation hybrid poplar ( 1), plants of 100 to 200 million gallons per year can be built -10 to 20 times as large as the example used in these calculations. This would reduce both capital and raw material costs. Perhaps we need to be bolder in our approach to design of ethanol from biomass. 

Wright. J.D. Ethanol from Biomass by Enzymatic Hydrolysis," Chem. Eng. Progress, 62 (August 1988). 

Foam fractionation is a promising technique for concentrating proteins because of its simplicity and low operating cost. One such protein that can be foamed is the enzyme cellulase. The use of inexpensively purified cellulase may be a key step in the economical production of ethanol from biomass. We conducted foam fractionation experiments at total reflux using the cellulase component P-glucosidase to study how continuous shear affects P-glu-cosidase in a foam such as a fermentation or foam fractionation process. The experiments were conducted at pH 2.4, 5.4, and 11.6 and airflow rates of 3,... 

At current crude oil prices, the production of ethanol from biomass is not profitable, either. Whether produced from beets, sugar cane, or com, it can become competitive only if it is subsidized. And these subsidies would only be forthcoming for political reasons to please their farmer voters, the French, Brazilian, and United States governments... 

Yeast separation and concentration. Extraction of ethanol from biomass requires several separation steps, traditionally by centrifuging, sedimentation and cake filtration. First, after the fermentation, the yeast is removed from the fermentation broth and may be recycled. Additionally, after ethanol is stripped from the fermentation broth by steam followed by the removal of solid fractions, the remaining material called the thin stillage can be clarified for reuse upstream as the process water. 

Yamamura T, Kondo M, Abe J, Kita H, and Okamoto K. The vapor permeation module using zeohte NaA membrane for producing absolute ethanol from biomass ethanol. Proceedings of the Eight International Conference on Inorganic Membranes, Cincinnati, OH, July 18-22, 2004 599-603. 

Producing methanol from biomass or coal costs about twice as much as producing it from natural gas. This encourages the use of nonrenewable petrochemical sources over biomass or coal. Considering the full production cycle, methanol from biomass emits less carbon dioxide than ethanol from biomass. This is because short rotation forestry, the feedstocks of methanol, requires the use of less fertilizer and diesel tractor fuel than the agricultural starch and sugar crops which are the feedstocks of ethanol. 

Ethanol-from-biomass fermentation is an example of product inhibition, while high fermentable carbohydrate concentrations also can become inhibitive. Aiba and Shoda developed a mathematical model for the anaerobic fermentation, where nine constants are required to describe the model,... 

Bioethanol (ethanol from biomass) is nowadays the largest fermentation product obtained from sugar cane. In fact, bioethanol seems to be the most promising alternative energy source to be used as a fiiel, either alone or as mixture in gasoline. Besides, from bioethanol, many chemicals products may be produced, making the sugar cane-based feedstock process... 

Acknowledgment for support of this work is made to the Ethanol from Biomass Program of the Biofuels Systems Division at the U.S. Department of Energy, the Vincent Johnson Lignin Research Fund at the University of Minnesota, the Minnesota State Legislature at the recommendation of the Legislative Commission on Minnesota Resources, and the Minnesota Agricultural Experiment Station. 

Clausen EC, Gaddy JL (1996) Ethanol from biomass by gasification/fermentation. In Khan MR (ed) Conversion and utilization of waste materials. Taylor Francis, Washington DC, pp 157-167... 

James Spearot I can t answer your question specifically with numbers. All I can tell you right now is that our analyses have been based on total life-cycle energy and materials costs, and based on these total life-cycle analyses, we believe that ethanol from biomass is competitive. Ethanol from cellulose is more expensive than petroleum-based energy forms today, but there is a very real reason to think that improvements can be made in cellulose processing techniques that would allow us to bring the cost of the ethanol derived from cellulose down to a competitive level. 

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