Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Young-Doo Wang, School of Urban Affairs & Public Policy. Includes bibliographical references.

The increased need for and scarcity of hydrocarbon energy pushes the search and extraction of reserves toward more technically difficult deposits and less efficient forms of hydrocarbon energy. The increased use of hydrocarbons also predicates the increased emission of detrimental chemicals in our surrounding environment. For these reasons, there is a need to find feasible sources of renewable energy that could prove to be more environmentally friendly. One possible source that meets these criteria is biomass, which in the United States is the largest source of renewable energy as it accounts for over 3 percent of the energy consumed domestically and is currently the only source for liquid renewable transportation fuels. Continued development of biomass as a renewable energy source is being driven in large part by the Energy Independence and Security Act of 2007 that mandates that by 2022 at least 36 billion gallons of fuel ethanol be produced, with at least 16 billion gallons being derived from cellulose, hemi-cellulose, or lignin. However, the production of biomass has drawbacks. The market for cellulosic bio-fuel feedstock is still under development, and being an innovative technique, there is a lack of production knowledge on the side of the producer. Some studies have been conducted that determine farmers’ willingness to produce switchgrass, however, they have been limited in geographic scope and additional research is warranted considering a broader area. Also, there have been production decision tools aimed at bio-mass, but these have either not been aimed at switchgrass specifically or have been missing key costs such as those incurred in storage. The overall objectives of this study are: 1.) to analyze the willingness of producers in the southeastern United States to plant switchgrass as a biofuel feedstock, 2.) to estimate the area of switchgrass they would be willing to plant at different switchgrass prices, 3.) to evaluate the factors that influence a producer’s decision to convert acreage to switchgrass, and 4.) to present a spreadsheet-based decision tool for potential switchgrass producers.

<p>This essay is written within my education for Technical Officer in the Swedish armed forces. The essay describes the alternative fuels that the Swedish armed forces can make use of if the supply of fossil fuels is insecure. The alternative fuels that are described and compared are; Synthetic diesel, Organic diesel, Methanol and Ethanol. The essay describes the process of producing the alternatives, the need for modification and the economics for each alternative. The alternatives are compared and assessed for their ability to secure the supply of fuel to the Swedish Armed Forces. The result of the study is that, while synthetic diesel has the best chemical constitution but is not produced in Sweden, the best alternative fuel for the Swedish armed forces at this moment is organic diesel.</p>

High temperature filtration in combustion and gasification processes is a highly interdisciplinary field. Thus, particle technology in general has to be supported by elements of physics, chemistry, thermodynamics and heat and mass transfer processes. This topic can be addressed in many ways, phenomenological, based on the up stream processes (i.e. dust/aerosol formation and characterisation) or apparatus oriented. The efficiency of the thermochemical conversion process and the subsequent emission control are major important areas in the development of environmentally sound and sustainable technology. Both are highly important for combustion and gasification plant design, operation and economy. This thesis is divided into four parts: I. High temperature cleaning in combustion processes. II. Design evaluations of the Panel Bed Filter technology. III. Biomass gasification IV. High temperature cleaning of biomass gasification product gas The first part validates the filter performance through field experiments on a full scale filter element employed to a biomass combustion process and relates the results to state of the art within comparable technologies (i.e. based on surface filtration). The derived field experience led to new incentives in the search for a simplified design featuring increased capacity. Thus, enabling both high efficiency and simplified production and maintenance. A thorough examination of design fundamentals leading to the development of a new filter geometry is presented. It is evident that the up-stream process has significant influence upon the operation conditions of a filter unit. This has lead to a detailed investigation of some selected aspects related to the thermochemical conversion. Furthermore, the influence of fuel characteristics upon conversion and product gas quality is discussed. The last part discusses the quality of biomass gasification product gas and requirements put upon the utilisation of this gas in turbines, diesel engines or other high temperature applications. Filtration experiments conducted on product gas derived from wood gasification are reported and discussed.

At present, the main cooking fuels inChinaare natural gas, coal gas, liquefied petroleum gas (LPG), coal, biogas, wood and straw. This paper reviews the characteristics, advantages, disadvantages and the current application status of these different cooking fuels. Moreover, a questionnaire survey is presented, dealing with different cooking fuels in Chinese households and the occupants’ perceived health, ventilation behaviors and general knowledge in potential health hazards. About 56% of the respondents of the questionnaire survey stated that symptoms like itching eyes, dry or irritated throat, irritated nose, running or blocked nose and headache were worse when they were cooking in their kitchens. This suggests that cooking fuel combustion has a significant influence on human health. The most evident health effect was that wood and straw as cooking fuel caused eye irritation. The present common house planning in Chinese countryside, where the kitchens are separated from the rest of the house via a courtyard, is very likely to reduce the stove contaminant exposure of all occupants.   In general, the main cooking fuels of the cities tend to be better than the cooking fuels of the countryside. Natural gas appears to be the cleanest cooking fuel among all urban cooking fuels except electricity. For the rural residents, biogas or LPG is a better choice than wood, straw and coal as cooking fuel.

A SuperCritical Water-cooled Nuclear Reactor (SCWR) is a Generation IV concept currently being developed worldwide. Unique to this reactor type is the use of light-water coolant above its critical point. The current research presents a thermal-hydraulic analysis of a single fuel channel within a Pressure Tube (PT) - type SCWR with a single-reheat cycle. Since this reactor is in its early design phase many fuel-channel components are being investigated in various combinations. Analysis inputs are: steam cycle, Axial Heat Flux Profile (AHFP), fuel-bundle geometry, and thermophysical properties of reactor coolant, fuel sheath and fuel. Uniform and non-uniform AHFPs for average channel power were applied to a variety of alternative fuels (mixed oxide, thorium dioxide, uranium dicarbide, uranium nitride and uranium carbide) enclosed in an Inconel-600 43-element bundle. The results depict bulk-fluid, outer-sheath and fuel-centreline temperature profiles together with the Heat Transfer Coefficient (HTC) profiles along the heated length of fuel channel. The objective is to identify the best options in terms of fuel, sheath material and AHFPS in which the outer-sheath and fuel-centreline temperatures will be below the accepted temperature limits of 850°C and 1850°C respectively. The 43-element Inconel-600 fuel bundle is suitable for SCWR use as the sheath-temperature design limit of 850°C was maintained for all analyzed cases at average channel power. Thoria, UC2, UN and UC fuels for all AHFPs are acceptable since the maximum fuel-centreline temperature does not exceed the industry accepted limit of 1850°C. Conversely, the fuel-centreline temperature limit was exceeded for MOX at all AHFPs, and UO2 for both cosine and downstream-skewed cosine AHFPs. Therefore, fuel-bundle modifications are required for UO2 and MOX to be feasible nuclear fuels for SCWRs. / UOIT

The increasing use of ethanol as a gasoline additive has raised concerns over the potential impacts ethanol might have on groundwater contamination. In North America, 10% ethanol is commonly being added to gasoline (termed E10). Ethanol is usually denaturated with gasoline compounds before being transported; consequently E95 (95% ethanol) mixtures are also common. Therefore, spills with compositions ranging from E10 to E95 can be anticipated. The compounds of main concern associated with gasoline spills are benzene, toluene, ethylbenzene and xylenes (BTEX), trimethylbenzenes (TMBs) and naphthalene, due to their higher mobility and potential risks to human health. Ethanol is thought to increase mobility of the NAPL, create higher hydrocarbon concentrations in groundwater due to cosolvency, and decrease the rate of gasoline hydrocarbon biodegradation, with consequent increase in the length of the dissolved plumes. The objective of this research was to improve the knowledge about ethanol fate in the subsurface and the impacts it might have on the fate of gasoline compounds. To investigate that, laboratory experiments and controlled field tests supported by numerical modeling were conducted. To evaluate the impact of ethanol on dissolved hydrocarbon plumes, data from a controlled field test were evaluated using a numerical model. The mass discharge of BTEX, TMB and naphthalene from three sources (E0, E10 and E95) emplaced below the water table was compared to simulation results obtained in the numerical model BIONAPL/3D. It was shown that if ethanol fuel mixtures get below the water table, ethanol is dissolved and travels downgradient fast, in a short slug. Mass discharge from the E0 and E10 sources had similar hydrocarbon decay rates, indicating that ethanol from E10 had no impact on hydrocarbon degradation. In contrast, the estimated hydrocarbon decay rates were significantly lower when the source was E95. The aquifer did not have enough oxygen to support the mass loss observed assuming complete mineralization. Assuming a heterogeneous distribution of hydraulic conductivity did little to overcome this discrepancy. A better match between the numerical model and the field data was obtained assuming partial degradation of hydrocarbons to intermediate compounds, with consequent less demand for oxygen. Besides depending on the concentration of ethanol in the groundwater, the impact of ethanol on hydrocarbon degradation appears to be highly dependent on the aquifer conditions, such as availability of electron acceptors and adaptation of the microbial community. Another concern related to ethanol biodegradation is formation of explosive levels of methane. In this study, methane δ13C from toluene and ethanol as substrates was evaluated in microcosm tests. It was shown that methane is enriched in δ13C when ethanol is the substrate. Ethanol derived methane δ13C is in the range of -20‰ to 30‰, while methane from gasoline is around -55‰. The different ranges of δ13C allow it to be used as a tool to identify methane’s origin. This tool was applied to seven ethanol-gasoline contaminated sites. Methane origin could be clearly distinguished in five of the seven sites, while in the other two sites methane appears to have been produced from both ethanol and gasoline. Both ethanol and gasoline were identified as the source of methane in hazardous concentrations. The behaviour of ethanol fuels in the unsaturated zone was evaluated in 2-dimensional (2-D) lab tests and in a controlled field test. In the 2-D lab tests, dyed gasoline and ethanol were injected in the unsaturated zone simulated in a transparent plexiglass box packed with glass beads. Tests were performed under both static conditions and with horizontal groundwater flow. It was confirmed that some ethanol can be retained in the unsaturated zone pore water. However, most of the ethanol went through the unsaturated zone and reached the pre-existing gasoline pool. Ethanol displaced the NAPL to deeper positions, and it was shown that for large ethanol releases much of the gasoline can be displaced to below the water table. The ethanol that reaches the capillary fringe was shown to travel downgradient rapidly at the top of the capillary fringe, while ethanol was also retained in the unsaturated zone. The behaviour of ethanol fuel spills was further evaluated in a controlled field test. 200L of E10 containing around 5% MTBE was released into the unsaturated zone. Groundwater concentrations of ethanol, MTBE, BTEX, TMB and naphthalene above and below the water table were monitored downgradient of the source in multilevel wells. Lab tests were performed to evaluate the applicability of these samplers for volatile organic compounds. It was shown that volatilization losses might be significant when bubbles formation in the sampling line could not be avoided. A method for losses estimation and correction of the concentrations was developed. Concentrations in the source zone were measured in soil samples. Despite the thin (35 cm) unsaturated zone at the site, most of the ethanol was retained in the unsaturated zone pore water, above the capillary fringe. Being in zones of low effective hydraulic conductivity, ethanol was not transported downgradient, and remained in the unsaturated zone for more than 100 days. Ethanol mass discharge was much lower than would be anticipated based solely on the ethanol fraction in the gasoline and on its solubility. Oscillations in the water table, particularly when a shallow position was maintained for prolonged periods, flushed some ethanol to zones with high water saturation, where horizontal transport occurred. The ethanol that reaches the saturated zone appears in the downgradient wells as a slug, with relatively low concentrations. No effect of ethanol on gasoline hydrocarbons was observed, a consequence of most of the ethanol being retained in the unsaturated zone. In summary, spills of ethanol fuels might have two different outcomes, depending on whether most of the ethanol is retained in the unsaturated zone or if most reaches the capillary fringe and the saturated zone. The relation between the ethanol volume spilled and the retention capacity of the unsaturated zone will control the spill behaviour. The volume of ethanol that can be retained in the unsaturated zone is a function of the volume of water that is contacted by the infiltrating NAPL. Therefore, the type of soil, heterogeneities, depth to the water table and area of the spill will be determinant factors. If a relatively large volume of ethanol reaches the capillary fringe, ethanol will travel rapidly in the groundwater possibly in high concentrations, potentially enhancing dissolved hydrocarbon plumes. However, when most of the ethanol is retained in the unsaturated zone, it will likely be detected downgradient only in low concentration, and in pulses spread in time. In this scenario, impact on hydrocarbon plumes will be minor.

This essay is written within my education for Technical Officer in the Swedish armed forces. The essay describes the alternative fuels that the Swedish armed forces can make use of if the supply of fossil fuels is insecure. The alternative fuels that are described and compared are; Synthetic diesel, Organic diesel, Methanol and Ethanol. The essay describes the process of producing the alternatives, the need for modification and the economics for each alternative. The alternatives are compared and assessed for their ability to secure the supply of fuel to the Swedish Armed Forces. The result of the study is that, while synthetic diesel has the best chemical constitution but is not produced in Sweden, the best alternative fuel for the Swedish armed forces at this moment is organic diesel.

The increasing use of ethanol as a gasoline additive has raised concerns over the potential impacts ethanol might have on groundwater contamination. In North America, 10% ethanol is commonly being added to gasoline (termed E10). Ethanol is usually denaturated with gasoline compounds before being transported; consequently E95 (95% ethanol) mixtures are also common. Therefore, spills with compositions ranging from E10 to E95 can be anticipated. The compounds of main concern associated with gasoline spills are benzene, toluene, ethylbenzene and xylenes (BTEX), trimethylbenzenes (TMBs) and naphthalene, due to their higher mobility and potential risks to human health. Ethanol is thought to increase mobility of the NAPL, create higher hydrocarbon concentrations in groundwater due to cosolvency, and decrease the rate of gasoline hydrocarbon biodegradation, with consequent increase in the length of the dissolved plumes. The objective of this research was to improve the knowledge about ethanol fate in the subsurface and the impacts it might have on the fate of gasoline compounds. To investigate that, laboratory experiments and controlled field tests supported by numerical modeling were conducted. To evaluate the impact of ethanol on dissolved hydrocarbon plumes, data from a controlled field test were evaluated using a numerical model. The mass discharge of BTEX, TMB and naphthalene from three sources (E0, E10 and E95) emplaced below the water table was compared to simulation results obtained in the numerical model BIONAPL/3D. It was shown that if ethanol fuel mixtures get below the water table, ethanol is dissolved and travels downgradient fast, in a short slug. Mass discharge from the E0 and E10 sources had similar hydrocarbon decay rates, indicating that ethanol from E10 had no impact on hydrocarbon degradation. In contrast, the estimated hydrocarbon decay rates were significantly lower when the source was E95. The aquifer did not have enough oxygen to support the mass loss observed assuming complete mineralization. Assuming a heterogeneous distribution of hydraulic conductivity did little to overcome this discrepancy. A better match between the numerical model and the field data was obtained assuming partial degradation of hydrocarbons to intermediate compounds, with consequent less demand for oxygen. Besides depending on the concentration of ethanol in the groundwater, the impact of ethanol on hydrocarbon degradation appears to be highly dependent on the aquifer conditions, such as availability of electron acceptors and adaptation of the microbial community. Another concern related to ethanol biodegradation is formation of explosive levels of methane. In this study, methane δ13C from toluene and ethanol as substrates was evaluated in microcosm tests. It was shown that methane is enriched in δ13C when ethanol is the substrate. Ethanol derived methane δ13C is in the range of -20‰ to 30‰, while methane from gasoline is around -55‰. The different ranges of δ13C allow it to be used as a tool to identify methane’s origin. This tool was applied to seven ethanol-gasoline contaminated sites. Methane origin could be clearly distinguished in five of the seven sites, while in the other two sites methane appears to have been produced from both ethanol and gasoline. Both ethanol and gasoline were identified as the source of methane in hazardous concentrations. The behaviour of ethanol fuels in the unsaturated zone was evaluated in 2-dimensional (2-D) lab tests and in a controlled field test. In the 2-D lab tests, dyed gasoline and ethanol were injected in the unsaturated zone simulated in a transparent plexiglass box packed with glass beads. Tests were performed under both static conditions and with horizontal groundwater flow. It was confirmed that some ethanol can be retained in the unsaturated zone pore water. However, most of the ethanol went through the unsaturated zone and reached the pre-existing gasoline pool. Ethanol displaced the NAPL to deeper positions, and it was shown that for large ethanol releases much of the gasoline can be displaced to below the water table. The ethanol that reaches the capillary fringe was shown to travel downgradient rapidly at the top of the capillary fringe, while ethanol was also retained in the unsaturated zone. The behaviour of ethanol fuel spills was further evaluated in a controlled field test. 200L of E10 containing around 5% MTBE was released into the unsaturated zone. Groundwater concentrations of ethanol, MTBE, BTEX, TMB and naphthalene above and below the water table were monitored downgradient of the source in multilevel wells. Lab tests were performed to evaluate the applicability of these samplers for volatile organic compounds. It was shown that volatilization losses might be significant when bubbles formation in the sampling line could not be avoided. A method for losses estimation and correction of the concentrations was developed. Concentrations in the source zone were measured in soil samples. Despite the thin (35 cm) unsaturated zone at the site, most of the ethanol was retained in the unsaturated zone pore water, above the capillary fringe. Being in zones of low effective hydraulic conductivity, ethanol was not transported downgradient, and remained in the unsaturated zone for more than 100 days. Ethanol mass discharge was much lower than would be anticipated based solely on the ethanol fraction in the gasoline and on its solubility. Oscillations in the water table, particularly when a shallow position was maintained for prolonged periods, flushed some ethanol to zones with high water saturation, where horizontal transport occurred. The ethanol that reaches the saturated zone appears in the downgradient wells as a slug, with relatively low concentrations. No effect of ethanol on gasoline hydrocarbons was observed, a consequence of most of the ethanol being retained in the unsaturated zone. In summary, spills of ethanol fuels might have two different outcomes, depending on whether most of the ethanol is retained in the unsaturated zone or if most reaches the capillary fringe and the saturated zone. The relation between the ethanol volume spilled and the retention capacity of the unsaturated zone will control the spill behaviour. The volume of ethanol that can be retained in the unsaturated zone is a function of the volume of water that is contacted by the infiltrating NAPL. Therefore, the type of soil, heterogeneities, depth to the water table and area of the spill will be determinant factors. If a relatively large volume of ethanol reaches the capillary fringe, ethanol will travel rapidly in the groundwater possibly in high concentrations, potentially enhancing dissolved hydrocarbon plumes. However, when most of the ethanol is retained in the unsaturated zone, it will likely be detected downgradient only in low concentration, and in pulses spread in time. In this scenario, impact on hydrocarbon plumes will be minor.

This thesis provides macro-, meso- and micro-level analyses of a potential hydrogen refuelling network with a case study for the Kitchener census metropolitan area in Canada. It provides recommendations on the appropriate number of stations required to meet estimated demand for hydrogen refuelling. Furthermore, scenarios are produced using geographic information systems (GIS) to show possible networks. Micro-level analysis brings in the planning aspect of hydrogen specific zoning codes and the possible impacts of citizen and stakeholder resistances to hydrogen.