Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 57-66).

Environmental concerns about urban air quality, global climate change, energy security and economic considerations motivate a growing interest in alternative fuels for the transportation sector. Ethanol, a fermentation-derived fuel, can be produced by bioconversion of renewable materials, such as wood, grass, and waste. Combustion of ethanol fuel, in both neat and blended form, can improve the engine efficiency, and lower the emission of CO, NO[subscript x], and volatile organic compounds (VOC), hence reducing the urban ozone level. Moreover, enhanced agricultural activities for production and collection of lignocellulosic feedstocks and industrial developments for production of ethanol will help the economic growth by creating new jobs and new income sources. Bioconversion of lignocellulosic feedstocks into ethanol requires a pretreatment process to increase the digestibility of cellulose by cellulolytic enzymes. The dilute-sulfuric acid pretreatment can hydrolyze hemicelluloses (xylan), disrupt lignin structure, and increase the yield of ethanol production from fermentation of monomeric units of cellulose (glucose). In this study, herbaceous (corn stover and switchgrass) and woody (poplar chips) feedstocks were pretreated with dilute sulfuric acid (0.6, 0.9, and 1.2% w/w) in a batch reactor at relatively high temperatures (140, 160 and 180��C). A unifying kinetic model including reaction time, temperature and acid concentration was developed, and pertinent kinetic parameters were determined. This model can predict the percentages of xylan remaining in the pretreated solids, net xylose yield in the liquid prehydrolysate, and xylose loss after pretreatment of a feedstock at a certain set of reaction conditions. Using this model, four optimum reaction conditions for obtaining maximum net xylose yield in the liquid prehydrolysate were identified. The yield and rate of ethanol production from the optimum prehydrolysates by the pentose fermenting yeast, Pichia stipitis, were determined. It was found that pretreating the selected feedstocks at 170-180��C with 1.0-1.2% sulfuric acid for 1-3 min resulted in the recovery of 80-85% of the original xylan in the liquid prehyrolysate. It was also found that feedstocks with higher neutralizing capacity (e.g., corn stover) produced lower sugar yields as a result of acid neutralization. Pretreatment of feedstocks at conditions beyond the optimum reaction conditions would increase the extent of xylose degradation, and lower the yield and rate of ethanol production due to loss of fermentable sugars and formation of toxic byproducts. The optimum prehydrolysates of corn stover produced the highest yields of ethanol (0.39-0.47 g ethanol/g xylose) followed by switchgrass (0.36-0.45) and poplar (0.26-0.44). The inhibitory effects of byproducts (e.g., acetate) was more pronounced in poplar prehydrolysates. / Graduation date: 1997

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 80)

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed Mar. 19, 2009). Vita. Includes bibliographical references.

Thesis (Ph.D.)--University of Minnesota, 2007. / Advisers: Roger Ruan, Jun Zhu. Includes bibliographical references.

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 77-81).

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 128-133). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 128-133). Also available on the Internet.

Thesis (M.S.)--Baylor University, 2009. / Includes bibliographical references (p. 54-61).

Thesis ( MTech (Business Administration))--Cape Peninsula University of Technology, 2016. / Capital investment in bioethanol production requires sound economic feasibility studies. This study investigated the economic feasibility of using maize as a feedstock to produce bioethanol in South Africa. There is a huge opportunity to use dedicated underutilised arable land to grow maize which can be used for both consumption and bioethanol production. The study used 200 000 ton/year of maize that could have been exported to SADC countries to size a plant that produces 80 million litres per year of bioethanol. An advanced bioethanol processing technology that separates the fibre/bran which is burnt in a steam boiler to produce process steam was selected owing to advantages such as low energy consumption and capital expenditure on fermentation and distillation equipment. This study employed a combination of qualitative and quantitative methods to gather data. The findings from a qualitative instrument indicated that a majority of respondents were in favour of the decision of excluding maize made by the South African government. Putting security of food at risk and uncertainty in the profitability of a maize-fed bioethanol plant in the South African context, were two of the primary reasons the respondents opted for an explicit exclusion of maize as a feedstock. Findings from quantitative analysis revealed that the profitability of the bioethanol plant was largely influenced by the prices of feedstock and bioethanol. The 2016 fiscal year indicated the worst case scenario in terms of economic viability of the bioethanol. The astronomically high price of maize due to drought (R5000/ton) rendered the project unprofitable as all of the economic indicators were negative. In the same marketing year, however, the trade balance of maize was positive, indicating a surplus. The study recommended that all of the surplus maize should be exported because it is not economically viable to build a bioethanol plant. The 2011 fiscal year indicated the best case scenario in terms of the economics of the project. This was due to the decrease in price of maize (R1726/ton) and a slight increase in the price of bioethanol. All of the economic indicators were positive, suggesting the benefits of investing in bioethanol production. It was recommended that under normal conditions of maize production in South Africa, a bioethanol plant can be operated simultaneous to maize exportation to other countries without compromising food security, because a maize-fed bioethanol plant uses only a small proportion of maize (14.3%) from the total volume of maize that is exported. Furthermore, it generates more revenue (99.9%) compared to the maize export revenue. It was recommended that sensitivity analysis should be conducted in a holistic manner whereby all variables in the economic model must be adjusted to assess the impact of each on the overall project profitability.