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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

A Solid Biomass Fuel Ranking Tool

Arsenault, Samuel Peter January 2008 (has links)
Current methods of ranking and selecting biomass fuels are based on short lists of factors. The objective of this thesis is to develop and demonstrate a fuel ranking tool. Existing fuel decision methods and bioenergy technology are reviewed. A fuel ranking tool is then developed and demonstrated. Finally, a procedure for evaluating the thermal efficiency of a pellet stove bioenergy system is developed and implemented. The tool is designed to be applied by an engineer working in cooperation with the actual fuel user. The user identifies a list of all available fuels which are compatible with their specific energy system. The ranking tool is suitable for users of any sized bioenergy system used for space heating, processing heating, or electricity generation. Through effective communication the engineer lists the user’s performance requirements. Requirements considered in this thesis are economic cost of fuels, required storage space, combustion equipment cleaning, and air pollutants emitted during biofuel combustion. Performance indicators corresponding to the user’s requirements are then selected or developed by the engineer. Data is then collected by the engineer to be used for the evaluation of these indicators. The indicators are then combined using weighting factors by the engineer to assign a single numerical score to each fuel. These scores allow the fuels to quickly and easily be ranked by the user according to how well they satisfy the user’s requirements. The ranking tool is demonstrated by applying it to a situation of a pellet stove user with 3 available fuel types. The three fuels are ranked in terms of their ability to satisfy the user’s requirements with respect to economic cost, storage space, equipment cleaning, certain air pollutant emissions, and supporting the local economy. A pellet stove thermal efficiency evaluation method is used to determine the percentage of fuel heating value delivered as space heat to the room housing the stove. Natural and forced convection as well as radiation heat transfers are modeled. The procedure results in a thermal efficiency measurement of 62% +/- 1% and 58% +/- 1% for premium wood and wheat straw pellets, respectively.
102

Microbial Production and Characterization of 1,3-PDO by a Novel Lactobacillus panis Strain

2012 April 1900 (has links)
Interest in the aliphatic carbon compound 1,3-propanediol (1,3-PDO) has risen over the past 15 years. In part, this interest is due to the ability of 1,3-PDO to generate a variety of industrially relevant products such as the biodegradable polymer, polytrimethylene terephtalate. Our research group previously reported the identification of a novel Lactobacillus panis PM1 isolate capable of converting glycerol to 1,3-PDO. In this body of work, the effects of various process parameters and the ability of the novel L. panis isolate to produce 1,3-PDO in static and fed-batch cultures were examined. Data collected indicated that the concentrations of glycerol, and glucose, and pH, play a vital role in the optimized production of 1,3-PDO. Optimal conditions for the production of 1,3-PDO were determined to include: i) carbon-limited culture, defined as below 50 mM glucose and ii) growth at 37°C without agitation in the presence of glycerol (150 – 250 mM) at an elevated pH of 9 – 10. Factors such as inoculum size and temperature (OD600 in the range of 0.5 – 2 and a temperature range from 15° - 37°C) in a two-step fermentation showed insignificant variance in the production of 1,3-PDO. Initial fed-batch trials reflected the importance of pH on culture viability. A pH of 8 was determined to be necessary within culture parameters for the fed-batch production of 1,3-PDO. Further, the molar concentrations of 1,3-PDO produced were found to vary only slightly between fed batch culture and a static culture. The variance of 1,3-PDO production between the static and fed-batch trials was found to be 9.1 ± 4.9 mM for an average culture producing 85.3 ± 12.0 mM of 1,3-PDO. However, the mol concentrations of 1,3-PDO produced were found to be significantly higher with 22.3 ± 1.6 versus 5.3 ± 0.7 mmol 1,3-PDO produced for the fed batch versus the static cultures, respectively. The duration of 1,3-PDO production was found to be extended in the fed-batch model of production with increased levels of 1,3-PDO being produced over 120 hours. The cloning and characterization of the recombinant 1,3-PDO NAD+-dependent oxidoreductase also were explored to gain further insight into the native production of 1,3-PDO. Initial kinetic studies determined a Km value of 1.28 ± 0.57 mM for NAD+ versus 23.8 ± 1.1 mM for 1,3-PDO. The Km values demonstrated that the availability of NAD+/NADH may be a determining factor in 1,3-PDO concentration. These findings support the literature and the conclusion that the bottleneck in 1,3-PDO production lies in maintaining an available pool of NAD+/NADH while mitigating negative effects associated with the accumulation of toxic byproducts.
103

A Solid Biomass Fuel Ranking Tool

Arsenault, Samuel Peter January 2008 (has links)
Current methods of ranking and selecting biomass fuels are based on short lists of factors. The objective of this thesis is to develop and demonstrate a fuel ranking tool. Existing fuel decision methods and bioenergy technology are reviewed. A fuel ranking tool is then developed and demonstrated. Finally, a procedure for evaluating the thermal efficiency of a pellet stove bioenergy system is developed and implemented. The tool is designed to be applied by an engineer working in cooperation with the actual fuel user. The user identifies a list of all available fuels which are compatible with their specific energy system. The ranking tool is suitable for users of any sized bioenergy system used for space heating, processing heating, or electricity generation. Through effective communication the engineer lists the user’s performance requirements. Requirements considered in this thesis are economic cost of fuels, required storage space, combustion equipment cleaning, and air pollutants emitted during biofuel combustion. Performance indicators corresponding to the user’s requirements are then selected or developed by the engineer. Data is then collected by the engineer to be used for the evaluation of these indicators. The indicators are then combined using weighting factors by the engineer to assign a single numerical score to each fuel. These scores allow the fuels to quickly and easily be ranked by the user according to how well they satisfy the user’s requirements. The ranking tool is demonstrated by applying it to a situation of a pellet stove user with 3 available fuel types. The three fuels are ranked in terms of their ability to satisfy the user’s requirements with respect to economic cost, storage space, equipment cleaning, certain air pollutant emissions, and supporting the local economy. A pellet stove thermal efficiency evaluation method is used to determine the percentage of fuel heating value delivered as space heat to the room housing the stove. Natural and forced convection as well as radiation heat transfers are modeled. The procedure results in a thermal efficiency measurement of 62% +/- 1% and 58% +/- 1% for premium wood and wheat straw pellets, respectively.
104

Modeling of Biofuelled HCCI Engines with a Parallel Multizone Model

Visakhamoorthy, Sona January 2011 (has links)
With growing concerns over emissions, homogeneous charge compression ignition (HCCI) engines offer a promising solution through reducing NOx and particulate emissions and increasing efficiency. However, this technology is not without its challenges and numerical modeling of these engines can offer some insight into addressing these challenges. This study uses domain decomposition with FORTRAN MPI to subdivide computationally intensive sections of a 10 zone simulation model. Using an Intel i7 quadcore workstation the parallelized model reduced runtimes by half compared to serial computations. From here, two sets of biofuel experimental data were used to improve the validation base of the model. The fuels used were a simulated biomass derived gas (consisting of H2, CH4, CO, CO2, and N2) and a butanol/n-heptane blend. Once calibrated, the model showed good pressure, heat release, and products of incomplete combustion prediction for biogas. NOx emissions were high, however the overall trend was captured. Similarly, once calibrated to the butanol/n-heptane data to account for some of the effects of negative valve overlap (NVO), excellent pressure and heat release predictions were obtained. However, products of incomplete combustion and NOx were low and this was attributed to the inability of the model to properly account for inhomogeneity and all the effects of NVO. Once again though, the overall trend in NOx levels was captured by the model. It was also found that the model does not operate very well near the misfire limit of the engine as it cannot capture the cyclic variability that can occur here. Based on the two new validation cases, it is concluded that once calibrated, the model can be used as a predictive tool for pressure, heat release, and combustion phasing of biofuelled HCCI engines. Furthermore, to improve its predictive capabilities, it is recommended that the model be restructured to incorporate mass transfer between zones, a fixed crevice volume and variable thermal boundary layer, and a CFD solver to improve emissions predictions and reduce reliance on calibration. Finally, changing the zone distribution from ring like zones to lumped stirred reactors is recommended to allow for more realistic modeling of actual experimental HCCI conditions.
105

The Study of Phytoremediation of Diesel Contaminated Soils by Energy Crops

Lin, Jia-Ren 04 January 2012 (has links)
The objectives of this study are to use phytoremediation ecotechnology to improve the long-term soil pollution contaminated by petroleum and its refined products, and to explore the influence of environmental factors to the effective degradation of TPH.This study is divided into three stages.First, we selected the biofuel crops seeds to test their diesel fuel pollution tolerance.The crops include soybean¡Bsunflower¡Bcanola and corn.This four Taiwanese common energy crops were selected to manually configure three levels of diesel fuel pollution(1000¡B5000¡B10000 mg kg-1)in soil test the seed tolerance experiments.The experimental results in the first stage exhibited that the best energy crop species and non-edible crop(Jatropha),are selected in second phase for contaiminated soil degradation experiment to explore the possible influence of enviromented factors,such as soil moisture¡BpH¡Btotal plate¡Ketc,and to explore the applied fertilizer to increase soil nutrients,whether it will affect the degradation of diesel pollution.Finally, in the third phase, the energy crops were used in the oil-contaminated site to assess their decontamination efficiency. From June 2011 to November 2011, the experimental results shown in the first phase of seed tolerance test, for a period of 30 days showed that the soybean diesel-contaminated soil presented the best tolerance.Although the germination rate was increased with the concentration from 80% to 27%, it showed the best growth conditions.Therefore, in the second phase of test run, the speices of soybean and jatropha were selected prepared with concentrations of 1745¡B6271 and 10072 mg kg-1 dry soil. After 90 day for phytoremediation, soybean group(S) were found that the residual concentrations in soil were measured equal to 524¡B809 and 1913 mg kg-1 dry soil,with the removal rates of 69.97%¡B87.09% and 81.01% respectively.The concentration level of 10000 ppm was found not reach our control standard of 1000 ppm. The soil planted by jatropha(J) showed that residual concentration in soils equial to 303¡B1864 and 4837 mg kg-1 dry soil, with removal rates equal to 82.61%¡B70.27% and 51.98% respectively.Through statistical regression analytical results, the soybean can handle up to a concentration of 5300 mg/kg for diesel, while jatropha can handle up to 2170 mg/kg in this system. Except for the concentration level of 1000 ppm can reach our control standards, the other two groups were found below the control standard. To improve the removal efficieneies, it was suggested that phyto remediation time can be extended.
106

Twin screw extrusion pre-treatment of wheat straw for biofuel and lignin biorefinery applications

Ng, Thian Hong January 2013 (has links)
Pre-treatment of wheat straw(lignocellulosic) biomass is a crucial step as it has direct impact on the subsequent yield of enzymatic saccharification and alcohol fermentation processes in the production of biofuel. Twin screw extrusion is a highly feasible pretreatment method and has been received great interest in the recent year pre-treatment studies. Twin screw extrusion is a continuous process, where the biomass feedstock can be subjected to a combination of simultaneous physical, thermal and chemical treatments. Steam explosion is a batch process and is the most commonly used method for lignocellulosic pre-treatment. In the initial stage of this study, the yield of glucose obtained from enzymatic saccharification for both methods (extrusion and steam explosion) were compared to identify the most effective pre-treatment approach. Effectiveness of the conventional steam explosion pre-treatment was used as benchmark for the directions of development of effective extrusion fractionation for wheat straw. In subsequent study, the impact of physical operating parameters (moisture, barrel temperature, compaction, screw speed and size reduction before extrusion) over twin screw extrusion with and without NaOH were studied. Low temperature (50°C) and increased moisture extrusion were preferred extrusion conditions. Yield of glucose can be improved by addition of NaOH (0.04g / g straw) and barrel temperature profile optimisation. Post extrusion washing was recommended. Findings from FTIR and TGA help to understand the chemical and structural changes took place in the pre-treatment and can be correlated with the glucose yield at the end of enzymatic hydrolysis. Characterisation analysis was extended to FT-NIR, morphology, crystallinity and specific surface area analysis to analyse the structural changes of lignocellulose biomass in extrusion pre-treatment and correlation with glucose yield. Chemometric analysis was used to statistically process large amounts of spectral data. The PCA scores plots showed good cluster segregation of the samples and were thus able to distinguish the effects of different pre-treatment conditions. The PLS regression models for both FTIR and FT-NIR showed good statistical regression and predictive ability correlated to the glucose yield. For the lignin ultilisation study, crude lignin was recovered from black liquor and fractionated with solvents. Lignin and the fractions were characterised with solvent solubility, SEC, UV, FTIR, 1H and 13C NMR and evaluated for the antioxidant activity with AAI ranged from 0.3 to 2.4. Reason for the low performance was proposed and experiment was extended to the intended application performance screening. Lignin application study was further extended to assess the feasibility of using lignin as an antioxidant in carboxylated acrilonitrile-butadiene rubber, XNBR glove. Evaluation involved physical observation, mechanical properties and thermal analysis – DSC-OIT after incorporation of lignin into XNBR glove. Lignin antioxidant performance was compared with current chemical antioxidant in used in industry. A part from antioxidant behaviour, lignin was also found can enhance the softness of XNBR film after accelerated heat aging.
107

Biokuro rinkos dalyvių interesų suderinamumo modelis / Modell of interests compatibility of bio fuel market parcitipants

Tyla, Jonas 14 January 2009 (has links)
Magistrantūros studijų baigiamasis darbas, 59 puslapių, 11 paveikslų, 13 lentelių, 37 lite-ratūros šaltiniai, 3 priedai lietuvių kalba. Magistro darbe siekiama apibendrinti teorinius biokuro rinkos suderinamumo aspektus bei jų pritaikymo galimybes. Teorinėje dalyje analizuojami biokuro sistemos įvertinimo metodikos moksliniai spren-dimai, įvertinama Lietuvos biokuro verslo aplinka bei pateikiami biokuro rinkos veiklos suderi-namumo būdai. Tiriamojoje dalyje, remiantis teoriniu biokuro rinkos dalyvių ryšių įvertinimu, atliekamas biokuro rinkos dalyvių tyrimas. Pateikiamos teoriniu ir praktiniu biokuro rinkos suderinamumo tyrimu apibendrintos išvados ir rekomendacijos. Tyrimo objektas – biokuro rinka. Darbo tikslas – sukūrti biokuro rinkos dalyvių interesų suderinamumo modelį ir pagrįsti jo naudingumą. Tyrimo tikslui pasiekti darbe numatoma išspręsti šiuos uždavinius: 1) Nustatyti biokuro rinkos dalyvius ir jų tarpusavio santykius; 2) nustatyti galimus biokuro rinkos dalyvių interesų suderinamumo būdus; 3) parengti biokuro rinkos dalyvių interesų suderinamumo tyrimo metodiką; 4) pagal parengtą metodiką pasiūlyti sprendimus biokuro rinkos dalyviams. Tyrimo metodai - mokslinės literatūros analizė ir sintezė, loginė analizė ir sintezė, lygi-namoji analizė, struktūrinė santykinė analizė, statistinių duomenų analizė ir sintezė, grafinio vaizdavimo metodas. Teorinės dalies tyrimo metodikos santrauka pateikta straipsnyje „Biokuro rinkos suderi-namumo teoriniai aspektai“ (Tyla... [toliau žr. visą tekstą] / Research object – dimension compatibility of the biofuel market and its potencial use. In the theoretical part analysing biofuel system methodology scientific solution, rateab-ling Lithuanian biofuel bussines environment, and proceeding the way of the biofuel market compatibility. In the inquiring part, performing biofuel market users inquiring. Research object – biofuel market. Research aim – to value and to substantiate biomass and biofuel production and use sys-tem model compatibility, utility, expedience, and viable, also research plan arrangement premise. Objectives: 1) perform theoretic the analysis of biofuel market analysis, and to set it to use in heating energy make. 2) estimate potential ways of biofuel market. 3) frame the biofuel market methodology, to rate Lithuanian biofuel market procee-ding. 4) evaluate biofuel market in Lithuania according to the prepared methodology. Research methods: the analysis and synthesis of scientific literature, logical analysis and synthesis, comparable analysis, structural comparative analysis, the analysis and synthesis of sta-tistical information, graphic methods of modeling, method of rating. Teoretical part research methodology digest is given in the article „Theorical dimension compatibility of the biofuel market“ (Tyla, Ramanauskas, 2008).
108

The influence of irradiance and genotype on the change in carbon allocation by four species of microalgae under increasing nutrient stress

Bowen, David 27 November 2012 (has links)
During nutrient-replete growth of microalgae, new photosynthate is allocated toward three different biochemical pools: light harvesting compounds, the biosynthetic apparatus and energy storage. The mechanisms governing allocation of photosynthate between the energy storage compounds carbohydrate and lipid are not well understood. For biofuel production, it is desirable to identify conditions and algal strains that allocate maximum amounts of photosynthate to lipid. This thesis assessed the allocation of photosynthate toward the energy storage pool, and to lipid vs. carbohydrate, at two light levels and during ongoing nitrogen-starvation, for two diatoms and two chlorophytes. Nitrogen-starvation resulted in an increase in the photosynthate allocated toward energy storage, however the magnitude of change was determined by a combination of species and light level. Of the four species studied, the diatom Chaetoceros muelleri, grown in high light, accumulated lipid during N-starvation at a relatively high rate, making it a good candidate for biofuel production.
109

Three Essays on U.S. Agriculture under Climate Change: Active Engagement in Mitigation and Adaptation

Zhang, Yuquan 2011 December 1900 (has links)
This dissertation investigates: (1) the implications of including high-yielding energy sorghum under the Renewable Fuels Standard (RFS2) program; (2) the effects of RFS2 with and without projected climate change scenarios on U.S. agriculture; (3) the spatial distribution of cattle breeders in Texas to quantify how climate factors influence cattle breed selection. In the RFS2 energy sorghum work, the ability of the agriculture sector to meet the fuel requirements of RFS2 is examined with and without energy sorghum being a possibility using an agricultural sector model. The results show that energy sorghum would be a valuable contributor that would be used as a feedstock producing over 13 billion gallons per year of cellulosic ethanol. Without the presence of energy sorghum it is found that switchgrass serves as the major cellulosic ethanol feedstock. Findings also indicate that the presence of high-yielding energy sorghum does relax commodity prices and export reductions except for grain sorghum as energy sorghum competes with grain sorghum production. In addition, the results show that the introduction of energy sorghum has minimal effects on GHG mitigation potential in the agricultural sector. In the RFS2 and climate change research, the analysis shows that climate change eases the burden of meeting the RFS2 mandates increasing consumer welfare while decreasing producer welfare. The results also show that climate change encourages a more diversified use of biofuel feedstocks for cellulosic ethanol production, in particular crop residues. In the cattle breed research, summer heat stress is found to be a significant factor for breed selection: positive for Bos indicus and negative for Bos taurus and composite breeds. The estimation results also indicate a price-driven trade-off between Bos taurus and Bos indicus breeds.
110

An idea whose time had come: an exploratory analysis of ethanol's rise to agenda prominence in the United States

Shinn, Tanya January 2011 (has links)
This work investigates the question, “what made ethanol’s time come when it did?” The case examined is the Energy Policy Act of 2005 (P.L. 109-158), a landmark public policy law implemented in the United States to address the nation’s energy concerns. The Act’s emphasis on ethanol as a central part of the solution to address the energy crisis represented perhaps the most significant single policy shift in the history of the nation’s energy programme. This research draws attention to the process that resulted in ethanol being given a key role in American energy policy by investigating the pre-decision, agenda setting stage, of the process. Using qualitative research methodologies, this study conducts a historical case study analysis of the Energy Policy Act of 2005. The Multiple Streams agenda setting framework developed by Kingdon ([1984] 1995) is the one which forms the backbone of the study. This research suggests that the greatest influence on ethanol’s placement on the agenda was the way in which policy problems were constructed. When the energy, agricultural, and environmental problems that had garnered ethanol some legislative consideration in the 1970s and 1980s reemerged in the early 2000s, ethanol emerged as an attractive policy option that was seen as addressing each of these concerns. The role of interest groups and policy entrepreneurs helped to reinforce the relationship between these problems. The tactic of seeking aid from the United States Department of Agriculture (USDA) and the Environmental Protection Agency (EPA) had its advantages, as support from these agencies gave the proposals offered by pro-ethanol interest groups and corn state politicians greater weight. In addition, the fall in political influence of the petroleum industry (a traditionally effective oppositional force to the advance of ethanol) helped to facilitate and reinforce favourable political factors such as pro-ethanol presidential campaign platforms and a public mood that favoured decisive action. With some small modifications, Kingdon’s agenda setting framework, originally designed and applied in the context of health and transportation, holds up well when extended to the energy policy domain. One key point where the energy agenda setting process appears to diverge from Kingdon’s model occurs in the problem stream, which does not appear to be distinct from the political stream. Instead, this research suggests that problem definition plays a strong role in informing the content of the political stream. Kingdon’s framework has significant potential to enhance our knowledge of alternative energy policy formation.

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