Call number: LD2668 .T4 1986 C56 / Master of Science / Biological and Agricultural Engineering

In the current era, oil deficit countries around the world seriously consider shifting dependence from conventional gasoline to renewable bio-ethanol fuel in the transport industry. Arguably, blending l0vol% dry ethanol with 90vol% unleaded gasoline enables ethanol fuel to penetrate the fuel market at relatively lower development costs. Despite creating an important market for the ethanol industry, fuels containing dry ethanol of differential proportions multiply the local risks associated with fuel combustion. Making a sale of one drop of ethanol fuel, for example, is intrinsically tied to the sale of more drops of imported gasoline. Furthermore, an increase (decrease) in conventional fuel prices directly influences a decline (increase) in daily sales of ethanol fuel. Blending bio-ethanol fuel with conventional gasoline in various proportions fails to address the multifaceted fossil fuel crisis in oil deficit countries. Although reducing bio-ethanol production costs can buffer fuel prices to a significant degree when blended in higher ratios, industrial competition for bio-feedstock is a serious limitation for bio-ethanol development in all parts of the globe. Nevertheless, advances in biotechnology may allow the use of a wide range of cheaper ethanol feedstocks (e.g. lignocellulose) leading to an important reduction in ethanol production costs. Temporal and spatial variability of lignocellulosic ethanol potentials in the sugar industry is investigated over southern Africa as a whole. The influence of extremely low (high) production of sugar cane on the potentials development of lignocellulosic ethanol plants is demonstrated in this work. Characterization of bioethanol fuel markets on the basis of blending with gasoline is undertaken at the subcontinental scale. The connectivity between development, consumption per capita, population growth, bio-ethanol energy demand, as well as the critical limits of land stock potentials is examined in this study. On the basis of the special influence that each of the processes indicated above have on bio-ethanol fuel development, an integrated approach toward optimizing the total value of bio-ethanol fuel in the region is formulated. This approach allows the investigation to determine whether critical and beyond critical conditions of land stock lead to a collapse of a human consumption type or whether bio-ethanol fuel development is a totally viable process. Finally, this work ascertains whether sustainable biofuel development is an oxymoron because human development demands a constantly growing fuel consumption per capita, or because of increasing the lower limit, with an infinite upper limit for human development, or as a product of the combined effects of increasing human population with a higher consumption rate per capita of non-growing and non-developing land stock units. / Thesis (Ph.D.)-University of KwaZulu Natal, Durban, 2004.

Energy availability and environmental issues are of growing concern; nations are striving to use energy more efficiently while at the same time decreasing the negative impacts on the environment. / The objectives of this study are to: (1) establish a supply price for ethanol derived from switchgrass, (2) establish an accounting budget for carbon dioxide during feedstock production and processing into ethanol, and (3) determine the cost/tonne of CO$ sb2$ using this strategy. / Total cost of production of the feedstock for cycles of 5, 10, 15, and 20 years are $357.06/ha ( $32.73/ODT), $337.81/ha ( $30.96/ODT), $331.52/ha ( $30.39/ODT), and $328.47/ha ( $30.11/ODT) respectively. Thus, the approximate cost of producing one litre of ethanol from switchgrass is $0.47/litre. / Overall, the switchgrass-ethanol system is a net carbon sink for all four cycles, and each hectare of swithgrass sequesters between 1.9 and 6.8 tonne of CO$ sb2$ per year. However, this process is not indefinite, and will stop once the soil organic matter reaches an equilibrium. / The current price for gas is $0.24/litre (excluding taxes and profit margins). According to the price differential existing between ethanol and gasoline and the CO$ sb2$ emissions difference between both systems, the cost of sequestering CO$ sb2$ ranges between $83/tonne and $129/tonne, with the adoption of this specific strategy. At the macro level, Quebec and Canada's total carbon dioxide emissions reached 70 million tonnes and 461 million tonnes respectively, in 1991. Thus, displacing fossil-based energy sources (gasoline) with a renewable energy source (ethanol from switchgrass) to reduce those emissions by 20 % by the year 2010, incurs a cost ranging between $1.16 billion and $1.8 billion for Quebec, and between $7.7 billion and $11.9 billion for Canada. (Abstract shortened by UMI.)

On the forefront of the recent expansion in biofuels research is the production of cellulosic ethanol, or ethanol produced from a cellulose containing feedstock. Cellulose is a six-carbon polysaccharide found in most plant life and is one of the most abundant organic compounds on the planet. While the first generation of ethanol facilities uses sugar and starch based (corn kernels) plants as their feedstock, the next generation will use cellulosic sources such as wood chips, switchgrass, and forest residues. These cellulosic sources require far less energy and resources to grow and harvest, and are also much more abundant. A cellulosic source widely available in Georgia and much of the southeastern US is southern pine. This study involves the modeling of a complete 2000 dry ton per day pine to ethanol production facility with the AspenTech3 software Aspen Plus, which outputs a mass and energy balance as well as the capital cost of the equipment. A key parameter which affects the competitiveness of cellulosic ethanol is the internal processing energy required to convert the pine to ethanol. As a result, the heat and electrical load of every component within the facility is modeled and then quantified through the Aspen Plus simulation. After this base case energy analysis is developed, various alternate plant configurations are integrated in an attempt to reduce this process energy requirement. The material that is not fermented into ethanol is burned on-site to provide steam and electricity to the plant, as well as excess electricity to be sold to the grid as a byproduct. As the facility processing energy requirement is decreased, more excess electricity is available for sale. The implementation of the alternate distillation scenarios effectively reduce the internal processing energy in a manner as to increase the amount of excess electricity sold to the grid by 13.5%. The additional equipment required in this alternate scenario returns a simple payback period of 1.1 years through the additional revenue of the increased electricity sale.

The objective of this study was to investigate the possibility of recycling enzymes during saccharification of cellulose for the production of ethanol from woodchips. To make enzyme recycling feasible and economical when woodchips are processed for ethanol, the lignin in the wood is to be removed before the enzymes are added. Since enzymes constitute a major part of the input costs, second only to the feedstock, the ability to reuse the enzymes could lead to a considerable decrease in the production cost of ethanol. Tulip poplar woodchips were selected as the feedstock. Different delignification methods with recovery of byproducts were investigated. Alkali extraction, using dilute NaOH for the removal of lignin after steam pretreatment, was used as the base case against which all other processes were compared. Recovery of furfural and methanol, produced during the pretreatment of the woodchips, for sale as byproducts was one modification to the alkali extraction process that was investigated. The conversion of xylose to furfural and the recovery of the furfural as a byproduct was the third case explored. Solvent extraction using a 50:50 ethanol-water mixture instead of extraction with NaOH was the fourth case examined. Process flow sheets were then developed to recycle the enzymes during the hydrolysis and fermentation of this prehyrolyzed and delignified wood. Two reactor setup schemes were examined for enzyme recycling. One scheme involved a single train of reactors, with the whole pretreated slurry flowing from one reactor to the next, whereas, in the other scheme, the slurry was split among parallel trains of reactors. The activity loss of the enzymes was modeled such that a part of the enzymes entering the reactor lost all their activity. The loss of activity in multiple steps, with enzymes losing only some of their activity, was also modeled. Here the enzymes entering the reactor constituted a mixture with different activities instead of all the enzymes having the same activity like in the previous single step model. Recovering methanol and furfural reduced the minimum ethanol selling price. High temperature ethanol water pretreatment and lignin extraction reduced the minimum ethanol selling price compared to the base case of steam pretreatment followed by alkali extraction. Enzyme recycling also reduces the minimum ethanol selling price. The magnitude of the price reduction depends on the recycling scheme selected and the rate of enzyme deactivation, which has not been measured.

Thesis (M.S.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 74-78).

Thesis (M.S.)--Ohio University, March, 2008. / Title from PDF t.p. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains xv, 98 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 84).

Thesis (M.S. (Hons.))-- University of Western Sydney, 2008. / A thesis sumitted to the University of Western Sydney in fulfilment of the requirements for the degree of Masters of Science (Honours), School of Natural Sciences, College of Health and Science. Includes bibliography.

Thesis (M.S.)--Missouri University of Science and Technology, 2009. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed August 10, 2009) Includes bibliographical references (p. 58-64).