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Comprehensive analyses are conducted of the holistic farm production-harvesting-transporting-pre-refinery storage supply chain paradigm which represents the totality of important issues affecting the conversion facility front-gate costs of delivered biomass feedstocks. Targeting the Middle Gulf Coast, Edna-Ganado, Texas area, mathematical programming in the form of a cost-minimization linear programming model(Sorghasaurus) is used to assess the financial and economic logistics costs for supplying a hypothetical 30-million gallon conversion facility with high-energy sorghum (HES) and switchgrass (SG) cellulosic biomass feedstock for a 12-month period on a sustainable basis. A corporate biomass feedstock farming entity business organization structure is assumed. Because SG acreage was constrained in the analysis, both HES and SG are in the optimal baseline solution, with the logistics supply chain costs (to the front gate of the conversion facility) totaling $53.60 million on 36,845 acres of HES and 37,225 acres of SG (total farm acreage is 187,760 acres, including HES rotation acres), i.e., $723.67 per harvested acre, $1.7867 per gallon of biofuel produced not including any conversion costs, and $134.01 per dry ton of the requisite 400,000 tons of biomass feedstock. Several sensitivity scenario analyses were conducted, revealing a potential range in these estimates of $84.75-$261.52 per dry ton of biomass feedstock and $1.1300-$3.4870 per gallon of biofuel. These results are predicated on simultaneous consideration of capital and operating costs, trafficable days, timing of operations, machinery and labor constraints, and seasonal harvested biomass feedstock yield relationships. The enhanced accuracy of a comprehensive, detailed analysis as opposed to simplistic approach of extrapolating from crop enterprise budgets are demonstrated. It appears, with the current state of technology, it is uneconomical to produce cellulosic biomass feedstocks in the Middle Gulf Coast, Edna-Ganado, Texas area. That is, the costs estimated in this research for delivering biomass feedstocks to the frontgate of a cellulosic facility are much higher than the $35 per ton the Department of Energy suggests is needed. The several sensitivity scenarios evaluated in this thesis research provides insights in regards to needed degrees of advancements required to enhance the potential economic competitiveness of biomass feedstock logistics in this area.

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Okra (Abelmoschus esculentis) is a warm weather vegetable crop with seed characteristics similar to cotton. Putative similarities between these crops make okra a potential candidate as a biodiesel feedstock. The objectives of this research are to determine an optimal inter and intra-row spacing combination to maximize seed yield, and determine optimal plant characteristics for seed yield, oil production, and fatty acid profiles. Data indicated treatments of (22.86 x 7.62, 22.86 x 22.86, and 45.72 x 30.48 cm) were better than 91.44 x 15.24 cm with respect to seed yield, although, 45.72 x 30.48 and 91.44 x 15.24 cm are the same plant population. Variety trials indicated that Annie Oakley II produced substantial seed and oil yields of 3547 kg ha-1 and 1376 L ha-1, respectively in 2009. Data indicated palmitic, linoleic, and linolenic acids to be the primary constituents of okraseed oil.

>Magister Scientiae - MSc / Ethylene and propylene are greatly used for their importance as feedstocks for producing useful materials. Due to rise in prices and the demand of ethylene and propylene, the need to increase the selective production of these light olefins is necessary. To achieve this, zeolites, specifically ZSM-5 has been used to investigate catalytic cracking of several types of hydrocarbons for the production of these light olefins. This study focuses on developing hierarchical macro and/or mesoporous ZSM-5 zeolites with variable Si/Al ratios. The synthesized materials were then evaluated on their performance via catalytic cracking of hexane, dodecane and tyre derived oil [TDO] to produce light olefins, particularly ethylene and propylene.

Research was conducted at Virginia Tech on a high-pressure uncooled plasma torch to study torch operational characteristics with hydrocarbon feedstocks and to determine the feasibility of using the torch as an igniter in scramjet applications. Operational characteristics studied included electrical properties, such as arc stability, voltage-current characteristics and start/re-start capabilities, and mechanical properties, such as coking, electrode erosion and transient to steady-state torch body temperature trends. Possible use of the plasma torch as an igniter in high-speed combustion environments was investigated through the use of emission spectroscopy and a NASA chemical kinetics code. All feedstocks tested; argon, methane, ethylene and propylene, were able to start. The voltage data indicated that there were two preferred operating modes, which were well defined for methane. For all gases, a higher current setting, on the order of 40 A, led to more stable torch operation. A low intensity, high frequency current applied to the torch, along with the primary DC current, resulted in virtual elimination of soot deposits on the anodes. Electrode erosion was found to multiply each time the complexity of the hydrocarbon was increased. Audio and high-speed visual analysis led to identification of 180 Hz plasma formation cycle, related to the three-phase power supply. The spectroscopic analysis aided in the identification of combustion enhancing radicals being produced by the torch, and results of the chemical kinetics analysis verified combustion enhancement and radical production through the use of a basic plasma model. Overall, the results of this study indicate that the plasma torch is a promising source for scramjet ignition, and further study is warranted. / Master of Science

Polymer hydrolysis is the first (and rate limiting) step for biomethanation of heterogeneous biomass feedstock’s. Satisfactory hydrolysis has been difficult to achieve, understand and predict adequately, to run anaerobic bioreactors with such feedstock’s efficiently. The fraction of hot water soluble extracts (crude proteins and extractables, Fcpe), the nature and material of intercellular binding and the extent and complexity of lignin present have been considered as key parameters for hydrolysis and has been analyzed for a variety of biomass degradation data available at the Centre for Sustainable Technologies, Indian Institute of Science. Feedstocks were grouped into those bound with high levels of pectic/protein materials or lignin-bound types. The data on the initial (10-15d) as well as the overall rates of hydrolysis (0-50d) has been analyzed. The extent of hydrolysis achieved for pectin bound substrates were high (≥65%) and that of lignin bound substrate was low (≤30% VS, Acacia). The initial hydrolysis rates were strongly correlated to the content of extractables (=0.117Fcpe). Subsequently, the hydrolysis rates rise to reach maxima and then begin to fall. Most fresh feedstock had somewhat similar rates of the increase in hydrolysis rates but the time to reach maximum and its value varied among feed stocks. Many lignin bound feed stocks did not have such a pattern. With regards to the overall hydrolysis rate constant, it was found that these clustered into two groups that represented pectin bound (0.154/d) and lignin bound (0.045/d) types. Therefore from this study it was concluded that anaerobic decomposition of heterogeneous biomass could be predicted using two rate parameters and one intrinsic property of the biomass feedstock, namely, a. the initial rate of hydrolysis (based on the extent of extractables =0.117 Fcpe) b.the maximum rate achieved and the time when it is reached (an intrinsic property based on feed stock and but not determined in this study) c. the overall hydrolysis rate (choosing between 0.154 /d or 0.045 /d depending upon the nature of inter-cellular binding material, pectin or lignin, respectively). This research provides new insights into the prediction of hydrolysis rate a key limiting step for heterogeneous biomass biomethanation (hydrolysis) based on the level of extractables, the type of cellular cementing material and the maxima that can be achieved.

Integrated bio-refineries offer a potential for a more sustainable production of fuels and chemicals. However, the sustainability implications of integrated bio-refineries are still poorly understood. Therefore, this work aims to contribute towards a better understanding of the sustainability of these systems. For these purposes, a methodological framework has been developed to assess the sustainability of different 2nd generation feedstocks to produce bio-ethanol, energy, and platform chemicals using bio-chemical or thermo-chemical routes in an integrated bio-refinery.The methodology involves environmental, techno-economic, and social assessment of the bio-refinery supply chain. Life cycle assessment (LCA) is used for the environmental assessment. The economic assessment is carried out using life cycle costing (LCC) along side traditional economic indicators such as net present value and payback period. Social issues such as employment provision and health and safety are considered within the social sustainability assessment. The methodology has been applied to two case studies using the bio-chemical and the thermo-chemical conversion routes and four feedstocks: wheat straw, poplar, miscanthus and forest residue.For the conditions assumed in this work and per litre of ethanol produced, the LCA results indicate that the thermo-chemical conversion is more environmentally sustainable than the bio-chemical route for eight out of 11 environmental impacts considered. The LCA results also indicate that the main hot spot in the supply chain for both conversion routes is feedstock cultivation. The thermo-chemical route is economically more sustainable than the bio-chemical because of the lower capital and operating costs. From the social sustainability point of view, the results suggest that provision of employment would be higher in the bio-chemical route but so would the health and safety risks.

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Doctor of Philosophy / Department of Agronomy / Charles W. Rice / Biofuel feedstocks such as grains and cellulose are gaining increased attention as part of the U.S. portfolio of solutions to address climate change and improve energy security. As the future of biofuels unfolds, major concerns are emerging, including the sustainability of the soil resource in bioenergy cropping system. With a clear understanding of the sustainability risks that exist within the agricultural soil resources, it is now essential to develop metrics that document the soil health as well as the total biomass production of different cropping system. We tested the effectiveness of eight bioenergy plant species grouped between annual and perennial crops. Our main objective was to determine the sustainability of bioenergy cropping systems. There was significantly greater soil structural stability plus greater root biomass under the perennial crops but greater aboveground biomass in the annual crop. Differences in soil carbon measured to 1.2 m were not significant between energy crops after five years. A transparent, unbiased method to identify possible change in soil characteristics under bioenergy cropping practice was offered. Our next metrics were soil aggregate stability and microbial community structure as indicators of soil ecosystem health and environmental stability. The effects 24 years of differing levels of residue and fertilizer inputs on soil aggregate stability, aggregate C and microbial community structure were evaluated. A native, undisturbed prairie site, located nearby was used as a reference in this study. The results showed that greater inputs of inorganic N and increased returns of crop residues did not cause a proportionately greater increase in SOC. The abundance of microbial parameters generally followed their potential carbon pool in cultivated soils but a strong mismatch was observed in the native prairie site. Our results showed for the first time a clear disconnect between decomposers and macroaggregates; highlighting the role of soil structure in protecting organic matter. Soil carbon sequestration is one of the mechanisms that have been proposed as temporary measure to mitigate global climate change. However, there was a particularly large risk of negative effects of mitigation measures related to the increased removal of crop residues from cropping systems for use in bioenergy, if this means that soil carbon is reduced. Effective measurement of soil C at the field scale requires an understanding of the spatial variability of soil C on a landscape scale. Recent technological advances in soil C measurement offer new opportunities in this area. Our surface measurements of soil C by near infrared spectroscopy (NIRS) provided a quick assessment of soil C and, soil C predicted by NIRS and measured by dry combustion laboratory measurements was correlated with and R-squared of 0.84.