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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.
291

Modeling Plot-Level Biomass and Volume Using Airborne and Terrestrial Lidar Measurements

Sheridan, Ryan D. 2011 May 1900 (has links)
The United States Forest Service (USFS) Forest Inventory and Analysis (FIA) program provides a diverse selection of data used to assess the status of the nation’s forested areas using sample locations dispersed throughout the country. Airborne, and more recently, terrestrial lidar (light detection and ranging) systems are capable of producing accurate measurements of individual tree dimensions and also possess the ability to characterize three-dimensional vertical forest structure. This study investigates the potential of airborne and terrestrial scanning lidar systems for modeling forest volume and aboveground biomass on FIA subplots in the Malheur National Forest, eastern Oregon. A methodology for the creation of five airborne lidar metric sets (four point cloud-based and one individual tree based) and four terrestrial lidar metric sets (three height-based and one distance-based) is presented. Metrics were compared to estimates of subplot aboveground biomass and gross volume derived from FIA data using national and regional allometric equations respectively. Simple linear regression models from the airborne lidar data accounted for 15 percent of the variability in subplot biomass and 14 percent of the variability in subplot volume, while multiple linear regression models increased these amounts to 29 percent and 25 percent, respectively. When subplot estimates of biophysical parameters were scaled to the plot-level and compared with plot-level lidar metrics, simple linear regression models were able to account for 60 percent of the variability in biomass and 71 percent of the variation in volume. Terrestrial lidar metrics produced moderate results with simple linear regression models accounting for 41 percent of the variability in biomass and 46 percent of the variability in volume, with multiple linear regression models accounting for 71 percent and 84 percent, respectively. Results show that: (1) larger plot sizes help to mitigate errors and produce better models; and (2) a combination of height-based and distance-based terrestrial lidar metrics has the potential to estimate biomass and volume on FIA subplots.
292

Characterization of an ethanologenic yeast inhibiting atypical galactose metabolism

Keating, Jeffrey Desmond 05 1900 (has links)
In the near future, biomass-derived energy is predicted to substantially complement that generated from petroleum. However, certain types of biomass employed as substrates in the microorganism-mediated production of renewable fuelethanol contain significant amounts of the recalcitrant hexose sugar galactose. The consumption of galactose in hexose sugar-fermenting yeasts is often delayed with respect to other sugars, such as glucose and mannose, because of an intrinsic preference for carbon sources requiring less energy in the preparatory reactions preceding glycolysis. This work comprised the search for, and characterization of anethanologenic yeast capable of efficiently assimilating galactose. Screening experiments conducted with wild-type Saccharomyces cerevisiae strains identified one isolate (Y-1528) exhibiting exceptionally fast galactose fermentation. The absence of conventional glucose repression, including a preference for galactose as carbon source and notable delays in the utilization of glucose and mannose, was demonstrated in mixed sugar fermentations. Endogenous extracellular glucose was observed during double sugar fermentations of galactose and mannose. This glucose was traced to supplied galactose by radioisotope labeling, suggesting involvement of UDP-galactose 4-epimerase in the responsible reaction mechanism(s).Sub-cellular fractionation was employed in an attempt to ascertain enzyme localization in Y-1528. Fermentations of lignocellulosic substrate mixtures by Y-1528 illustrated better performance than that accomplished by a reference yeast strain, and again showed a preference for galactose. Mixed cultures of Y-1528 and the same reference strain demonstrated accelerated hexose sugar consumption, and no detrimental effects from competition, during synthetic and lignocellulosic substrate fermentations. Glucose repression was absent in mixed culture fermentations. Fermentations of synthetic sugar mixtures augmented with lignocellulosic inhibitory compounds showed Y-1528 to have better performance than a reference yeast strain, despite a global detrimental effect relative to inhibitor-free fermentations. Cell recycle batch fermentations of spent sulfite liquor illustrated the toxic effect of the hardwood variant, as well as a net loss of performance from all strains tested. Y-1528 was taxonomically confirmed as S. cerevisiae. UDP-galactose 4-epimerase chromatographic purification was unsuccessful, but a partial sequence of the enzyme, showing complete identity with type sequence, was obtained by electrophoretic separation, liquid chromatography, and mass spectrometry. A significantly mutated UDP-galactose 4-epimerase gene was successfully sequenced.
293

BIOMASS PRODUCTION FOR ENERGY IN DEVELOPING COUNTRY : Case Study: CHINA and NIGERIA

Liu, Xiaolin, Balogun, Kazeem January 2012 (has links)
Most developing countries of the world still uses biomass for domestic energy, this is mostly used in the rural areas and using our case study which is Nigeria and China. We have been able to establish the potential of biomass production energy use by looking at calorific values of some biomass such As-harvested wood, Dry wood, Straw Miscanthus Coal  which was discussed on the introduction part of this thesis.
294

Energy ans exergy analysis of biomass co-firing in pulverized coal power generation

Mehmood, Shoaib 01 April 2011 (has links)
Biomass co-firing with coal exhibits great potential for large scale utilization of biomass energy in the near future. In the present work, energy and exergy analyses are carried out for a co-firing based power generation system to investigate the impacts of biomass cofiring on system performance and gaseous emissions of CO2, NOx, and SOx. The power generation system considered is a typical pulverized coal-fired steam cycle system, while four biomass fuels (rice husk, pine sawdust, chicken litter, and refuse derived fuel) and two coals (bituminous coal and lignite) are chosen for the analysis. System performance is evaluated in terms of important performance parameters for different combinations of fuel at different co-firing conditions and for the two cases considered. The results indicate that plant energy and exergy efficiencies decrease with increase of biomass proportion in the fuel mixture. The extent of decrease in energy and exergy efficiencies depends on specific properties of the chosen biomass types. The results also show that the increased fraction of biomass significantly reduces the net CO2 emissions for all types of selected biomass. However, gross CO2 emissions increase for all blends except bituminous coal/refuse derived fuel blend, lignite/chicken litter blend and lignite/refuse derived fuel blend. The reduction in NOx emissions depends on the nitrogen content of the biomass fuel. Likewise, the decrease in SOx emissions depends on the sulphur content of the biomass fuel. The most appropriate biomass in terms of NOx and SOx reduction is sawdust because of its negligible nitrogen and sulphur contents. / UOIT
295

Energy and exergy analyses of biomass cogeneration systems

Lien, Yung Cheng 01 August 2012 (has links)
Biomass cogeneration systems can generate power and process heat simultaneously from a single energy resource efficiently. In this thesis, three biomass cogeneration systems are examined. Parametric analysis of back pressure steam turbine cogeneration system, condensing steam turbine cogeneration system and double back pressure steam turbine cogeneration system is conducted. Energy and exergy analyses are performed for three biomass based cogeneration configurations. The parametric analysis demonstrates the effects of varying operating conditions (temperature: 340 oCto 520 oCand pressure: 21bar to 81bar). A higher steam inlet temperature and pressure to the turbine yields better energy and exergy efficiencies and performance. Steam inlet conditions to the turbines and process heater requirements influence the power output and cogeneration system efficiencies. Greenhouse gases reduction is achieved by cooperating cogeneration systems with biomass to reduce CO2 emissions and global warming potential in the power industrial sectors. / UOIT
296

Ecological and molecular studies of fungal communities associated with roots of <i>Salix spp.</i> grown under high density, short rotation intensive culture

Corredor, Aura Helena 22 February 2011
In Canada, willow (Salix spp.) short rotation intensive cultures (SRIC) have been established to investigate their potential to produce biomass for bioenergy. Since root-associated fungal communities are involved in plant nutrition and disease susceptibility, it is relevant to understand their interactions with willows and their role on the sustainability of SRIC. In this project traditional methods together with molecular techniques were used to: i) assess the diversity of fungal communities in roots of willows and their relationship with major characteristics of SRIC ii) evaluate the effects on plant development of potentially beneficial and pathogenic fungi, and iii) identify arbuscular mycorrhizal fungal (AMF) species and their interaction with promising Salix clones. Potentially pathogenic fungi were more dominant in diseased and recently planted cuttings than in healthy older ones. This suggested the occurrence of a positive shift prompted by the establishment of the cuttings on the site. Gibberella/Fusarium sp. and Neonectria sp. were the most dominant taxa particularly in diseased plants. Under greenhouse conditions the inoculation with potentially beneficial and potentially pathogenic fungi induced significant differences in root biomass but not in overall aerial biomass production. PCR-denaturing gradient gel electrophoresis was successfully standardized and used to identify arbuscular mycorrhizal fungal species associated with different clones. The results indicated a degree of specificity between AMF species and plant genotype. Root-associated fungal communities appear to be useful to monitor the impacts of SRIC on soil ecology and their study may enlighten effective ways to increase the productivity of these biomass systems.
297

Production of fuels and chemicals from biomass-derived oil and lard

Adebanjo, Adenike Omowunmi 25 February 2005
<p>Biomass derived oil (BDO) reforming with CO2 was carried out at 800oC under atmospheric pressure in a tubular fixed bed vertical reactor packed with quartz particles. The feed gas was a mixture of CO2 and N2 at various compositions with a flow rate of 30 to 60 cm3/min. The BDO flow rate was 5 g/h. The product gas consisted mostly of H2, CO, CO2, CH4 and C2H4.</p><p>The maximum production of synthesis gas (~76 mol%) was observed at a total carrier gas flow rate of 60 cm3/min and a mole fraction of CO2 in carrier gas of 0.1. Maximum hydrogen (42 mol%) and H2 to CO molar ratio (1.44) were obtained while using only N2 as the carrier gas at a flow rate of 50 cm3/min. In the range of residence time considered, CO2 was not consumed in BDO gasification at 800oC but helped to increase gas production at the expense of the char.</p><p>Pyrolysis of lard was performed to produce a diesel-like liquid and a high heating value gaseous fuel. Lard was fed into the reactor at 5 g/h using N2 (10-70 cm3/min) as carrier gas. Two particle size ranges of quartz particles (0.7-1.4 and 1.7-2.4 mm) were used as reactor packing material. The liquid product essentially consisted of linear and cyclic alkanes and alkenes, aromatics, ketones, aldehydes and carboxylic acids. The maximum yield for diesel-like liquid product (37g/100g lard) was obtained at 600oC, residence time of 1.5 s and packing particle size of 1.7- 2.4 mm. The liquid product obtained at 600oC, carrier gas flow rate of 50 cm3/min and quartz packing particle size of 0.7-1.4 mm has a cetane index of 46, specific gravity of 0.86, a heating value of 40 MJ/kg and cloud and pour points of 10 and -18 respectively. The heating value of the product gas ranged between 68 and 165 MJ/m3. This study shows that there is a potential for producing diesel-like liquid from pyrolysis of lard. It also identifies the pyrolysis of animal fats as a source of high heating value gaseous fuel.</p><p>Steam reforming of lard was performed at 500, 550, 600 and 800oC and at steam to lard mass ratios of 0.5 to 2.0. The maximum diesel-like liquid yield from the steam reforming process (39 g/100g of lard) was obtained at a steam to lard ratio of 1.5 and a temperature of 600oC. Higher cetane index (52) and lower viscosity (4.0 mPa.s at 40oC) were obtained by addition of steam. The net energy recovered from pyrolysis and steam reforming processes were 21.7and 21.9 kJ/g of lard respectively. Thus, the processes are energy efficient.</p><p>In comparison, lard is a better feedstock for the production of hydrogen, char, high heating value gas and high H2/CO ratio than BDO. On the other hand, BDO is the preferred feedstock for the production of synthesis gas with H2/CO in the vicinity of 1.</p>
298

Hydrogen Production using Catalytic Supercritical Water Gasification of Lignocellulosic Biomass

Azadi Manzour, Pooya 10 December 2012 (has links)
Catalytic supercritical water gasification (SCWG) is a promising technology for hydrogen and methane production from wet organic feedstocks at relatively low temperatures (e.g. <500 oC). However, in order to make this process technically and economically viable, solid catalyst with enhanced activity and improved hydrogen selectivity should be developed. In this study, different aspects of catalytic SCWG have been investigated. The performance of several supported-nickel catalysts were examined to identify catalysts that lead to high carbon conversion and high hydrogen yields under near-critical conditions (i.e. near 374 oC). Moreover, for the first time, the effects of several parameters which dominated the activity of the supported nickel catalysts have been systematically investigated. Among the several different catalyst supports evaluated at 5% nickel loading, α-Al2O3, carbon nanotube (CNT), and MgO supports resulted in highest carbon conversions, while SiO2, Y2O3, hydrotalcite, yttria-stabilized zirconia (YSZ), and TiO2 showed modest activities. Comparing the XRD patterns for the support materials before and after the exposure to supercritical water, α-Al2O3, YSZ, and TiO2 were found to be hydrothermally stable among the metal oxide supports. Using the same amount of nickel on α-Al2O3, the methane yield decreased by increasing the nickel to support ratio whereas the carbon conversion was only slightly affected. At a given nickel to support ratio, a threefold increase in methane yield was observed by increasing the temperature from 350 to 410 oC. The catalytic activity also increased by the addition small quantity of potassium. The activity of Ni/γ-Al2O3 catalyst varied based on the affinity of the catalyst to form nickel aluminate spinel. This is also the first report on the role of oxidative pretreatment of the carbon nanotubes by nitric acid on the performance of these catalysts for the supercritical water gasification process. Using different lignocellulosic feeds, it was found that the gasification of glucose, fructose, cellulose, xylan and pulp resulted in comparable gas yields (± 10%) after 60 min, whereas alkali lignin was substantially harder to gasify. Interestingly, gasification yield of bark, which had a high lignin content, was comparable to those of cellulose. In summary, the Ni/α-Al2O3 catalyst had a higher hydrogen selectivity and comparable catalytic activity to the best commercially available catalysts for SCWG of carbohydrates.
299

Fine root dynamics in the Boreal Forest of northern Saskatchewan, Canada

McDonald, Shawn Alexander 18 August 2010
The study of fine roots (FR) (roots < 2 mm in diameter) in the boreal forests has become a focus of many forest researchers in the past decade in an effort to better understand belowground processes and improve current carbon (C) models to better predict possible C sinks and sources. The objectives of this study were: 1) to determine the inter-annual variability in FR C production in relation to C cycling and other fluxes for four Saskatchewan boreal sites during a four year period, 2) to determine if minirhizotron (MR) estimates of root biomass were similar to root coring estimates, 3) to determine how root production, mortality, turnover, and longevity vary with root diameter class and soil depth, and 4) to determine if image collection orientation influenced estimates of FR biomass and production. Four Saskatchewan boreal sites including aspen (Populus tremuloides) (OA), black spruce (Picea mariana) (OBS), and two jack pine (Pinus banksiana) (mature OJP, young HJP94) stands were selected and MR were installed in July of 2002. Minirhizotron images were collected monthly from the end of May through September from 2003 to 2006. Total ecosystem C was estimated to be 47.5, 78.1, 163.1, and 450.5 Mg ha-1 for HJP94, OJP, OA, and OBS, respectively. The FR component of the ecosystem carbon storage ranged from 0.7 Mg ha-1 (1%) at HJP94 to 1.2 Mg ha-1 (< 1%) at OBS. Fine roots were found to contribute a very large portion of C production with estimates of 1.0, 0.6, 1.2, and 1.5 Mg ha-1 yr-1 accounting for 47, 27, 25, and 54% of total ecosystem C production at HJP94, OJP, OA, and OBS, respectively. In a one time comparison of MR and soil cores, FR biomass estimates were found to be similar at OJP, OA, and OBS, with MR estimates being significantly greater at HJP94. Approximately 85, 90, 96, and 96% of FR measured in this study were found to be less than 0.5 mm in diameter with median diameters of 0.250 ± 0.237, 0.225 ± 0.208, 0.175 ± 0.149 and 0.150 ± 0.149 (median ± SD) mm at HJP94, OJP, OA, and OBS, respectively. Fine root longevity was found to increase with increasing diameter and soil depth while turnover decreased. In many cases, it was found that even within a diameter interval of < 0.1 mm, differences in biomass, production, turnover, and longevity were detectable. This brings into question the use of the traditional 2 mm diameter class in FR studies. Fine root data, such as presented in this thesis, help to fill in some of the gaps in the knowledge base, enabling researchers to better understand the underground processes of the boreal forest and develop more complex and accurate C models.
300

Solid-state anaerobic digestion for integrated ethanol production

Lung, Patricia 09 November 2011
Anaerobic digestion (AD) is a biochemical process consisting of the microbiological conversion of organic materials for the purpose of generating biogas. Biogas is typically composed of 50 to 70% methane (CH4) and 50 to 30% carbon dioxide (CO2) with trace amounts of other compounds. Anaerobic digestion technology is a bioprocessing technology that has the potential to be integrated into an ethanol facility to further capture energy, in the form of methane gas, for use in a combined heat and power (CHP) generator or for integration into the natural gas pipeline grid after undergoing an upgrading process. The most simplistic design of an AD system is the solid state digester (SSD) which is able to process very high solids content materials (greater than 15% solids). A SSD has the potential to be utilized as a manure management system in a beef cattle feedlot and it has the potential to integrate seamlessly into a combined ethanol- feedlot operation to capitalize on the eco-cluster concept in bioenergy production. This thesis investigates the biogas and digestate composition seen from four material blends in a solid-state digester (SSD) system operated as a batch reactor. Wet distiller grains (WDG) from a grain ethanol process and cattle manure were the substrates investigated. To assess the biogas composition the system was operated over a period of time to achieve a quasi steady state within the microbial population to maximize the CH4 concentration in the biogas composition. To assess the robustness of the microbial population within each substrate blend, the biogas concentrations were measured over three cycle periods where a portion of the used substrate was replaced with an equal amount of fresh substrate. The digestate composition was analyzed at the end of each of the cycles and compared with the raw substrate to determine changes in solids and nutrient values. The biogas production calculated in this study determined 0.17, 0.21, 0.18, and 0.12L per gram (VS) within 100% WDG, 75%WDG and 25% manure, 25% WDG and 75% manure and the 100% manure substrate (Group 1 through 4) respectively, averaged over all three digestion cycles. At the end of three cycles of digestion the biogas within the substrate blend containing 25% WDG and 75% manure (Group 3) achieved a measured CH4 concentration of 49% and the biogas within the 100% manure substrate (Group 4) achieved a 59% concentration of CH4. The duration for each of Group 3 and Group 4 to achieve the production of viable biogas was 100 and 90 days of operation respectively. Thus it can be concluded that a SSD system start up duration will be between three and four months in duration. The gas data gathered in this research study indicates Group 3 had the most robust methanogenic culture established as it has the lowest overall N2 and CO2 concentration detected in the biogas, and the most consistent performance of CH4 production during each cycle. The investigation conducted on the nutrient data gathered in this research supports the conclusion drawn from the gas data regarding the overall methanogenic performance of the substrate blends. The nutrient data for Group 3 maintained an average carbon to nitrogen (C:N) ratio of 25:1 over all three digestion cycles. The nitrogen, phosphorous, potassium, and sulphur components of the manure fertilizer value were maintained through the digestion process of this investigation thus typical manure application rate calculations are applicable when field applying digestate.

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