Analysis of internal and external energy flows associated with projected process improvements in biomass ethanol production
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Possible improvements in biomass ethanol production are decribed involving heat-pumped distillation, steam-cycle heat integration, elimination of seed fermenters, pretreatment heat integration, advanced pretreatment, thermophilic DMC, and incrased carbohydrate yield to 90% of theoretical. Although speculative, a futuristic process incorporating these improvements may be useful for anticipating some features of a technologically mature biomass ethanol process, as well as for comparing ethanol production to more technologically mature energy-conversion processes. Relative to the current state-of-the-art National Renewable Energy Laboratory process design, the futuristic process has 101% higher electricity revenue, 31% hgiher ethanol revenue, and 35–39% higher overall revenue depending on the assumed ethanol value. The overall first-law thermodynamic efficiency is 43% for the current NREL design and 59% for the futuristic process. A general consideration of the costs associated with the process improvements examined indicates that:
Elimination of seed reactors, advanced pretreatment, and thermophilic DMC all have large potential cost reductions independent of their benefits with respect to increased surplus electricity;
Steam cycle improvements and pretreatment heat integration are expected to have modest cost benefits that are dependent on increased electricity revenues; and
The relative cost of heat-pumped distillation depends on scale, capital recovery, and electricity value, but is generally similar to the already low cost of conventional distillation provided that the fermentation broth has a reasonably high ethanol concentration.
A comparison of utilizing biomass for ethanol-electricity coproduction and utilizing biomass for dedicated electricity production indicates that these two alternatives have approximately equal economic benefits. At the electricity yields associated with the futuristic process, every 1% displacement of US transportation demand is accompanied by a 0.29% displacement of electricity demand, underscoring the potential significance of electricity coproduced with ethanol in meeting energy needs.
- Chem Systems. Technical and Economic Evaluation, Wood to Ethanol Process. Office of Energy Demand Policy, Department of Energy, Washington, in press.
- Lynd, L. R., Cushman, J. H., Nols, R. J., and Wyman, C. E. (1991),Science 251, 1318. CrossRef
- Lynd, L. R. and Grethlein, H. E. (1984),Chem. Eng. Prog. 81, 59.
- Torres, H. L., Grethlein, H. E., and Lynd, L. R. (1989),Appl. Biochem. Biotechnol. 20/21, 621. CrossRef
- South, C. R., Hogsett, D. A., and Lynd, L. R. Accepted byEnz. Microb. Technol.
- South, C. R., Hogsett, D. A., and Lynd, L. R. (1993),Appl. Biochem. Biotechnol. 39/40, 587–600. CrossRef
- Ladisch, M. and Schwandt, R. (1992), Report of the starch conversion work grop, inProceedings, Technology for Expanding the Biofuels Industry, Biofuels Program, Department of Energy, Washington.
- Heitz, M., Capek-Menard, E., Koeberle, P. G., Gagne, J., Chornet, E., Overend, R. P., Taylor, J. D., and Yu, E. (1991),Bioresource Technol. 35, 23. CrossRef
- Hogsett, D. A., Ahn, H.-J., Bernardez, T. D., South, C. R., and Lynd, L. R. (1992),Appl. Biochem. Biotechnol. 34/35, 527. CrossRef
- Lynd, L. R. (1989), Fiechter, A. ed., inAdv. Biochem. Eng./Biotechnol. 38 1.
- Analysis of internal and external energy flows associated with projected process improvements in biomass ethanol production
Applied Biochemistry and Biotechnology
Volume 51-52, Issue 1 , pp 569-584
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