Despite increasing fuel cost volatility, regulatory uncertainty, and imminent shifts to industry dynamics, utility managers are forced to make tough decisions in regards to installing long-life generation assets. This study seeks to identify and quantify determinants of fuel choice in new electric power plants given vast uncertainties in the electricity generation sector. Using a probit functional form to estimate marginal effects on the likelihood of choosing wind versus natural gas powered generation, I find positive effects of natural gas prices in the period three years prior to initial operation of the new facility, positive effects of static-level standard score of mix, and positive effects of wind-power density. Additional feedstock choice sets and parameters are considered. All models suggest that (a) feedstock costs are significant predictors of fuel choice, (b) state-level regulatory learning enhances likelihood of choosing relatively young technologies, (c) Renewable Portfolio Standards result in artificial substitution between wind and solar technologies, and (d) population density, more so than political influence, predicts choices to install wind-powered capacity. Public policy and managerial implications are discussed.

The mathematical analysis has been developed by using finite volume method, experimental data from literatures, and solving numerically to predict solid oxide fuel cell performances with different operating conditions and different material properties. The in-house program presents flow fields, temperature distributions, and performance predictions of typical solid oxide fuel cells operating at different temperatures, 1000 C, 800 C, 600 C, and 500 C, and different electrolyte materials, Yttria-Stabilized zirconia (YSZ) and Gadolinia-doped ceria (CGO). From performance predictions show that the performance of an anode-supported planar SOFC is better than that of an electrolyte-supported planar SOFC for the same material used, same electrode electrochemical considerations, and same operating conditions. The anode-supported solid oxide fuel cells can be used to give the high power density in the higher current density range than the electrolyte-supported solid oxide fuel cells. Even though the electrolyte-supported solid oxide fuel cells give the lower power density and can operate in the lower current density range but they can be used as a small power generator which is portable and provide low power. Furthermore, it is shown that the effect of the electrolyte materials plays important roles to the performance predictions. This should be noted that performance comparisons are obtained by using the same electrode materials. The YSZ-electrolyte solid oxide fuel cells in this work show higher performance than the CGO-electrolyte solid oxide fuel cells when SOFCs operate above 756 C. On the other hand, when CGO based SOFCs operate under 756 C, they shows higher performance than YSZ based SOFCs because the conductivity values of CGO are higher than that of YSZ temperatures lower than 756 C. Since the CGO conductivity in this work is high and the effects of different electrode materials, they can be implied that conductivity values of electrolyte and electrode materials have to be improved.

Thesis (Ph. D.)--Cornell University, 1928. / The first article is from the University of the Philippines Natural and applied science bulletin, v. 1, no. 3, July, 1931 and the second ("Experiment station contribution no. 742") from the Philippine agriculturist, v. 20.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 137-145). Also available in electronic version.

<p> The unique features of the Interrupted Thorium Cycle owing to Pa-233 have been examined including possible implications for practical implementation of the cycle. Generalized trajectories for the fuel inventories of fusion-fission symbionts are derived through a comprehensive parametric analysis. The resultant formulations are then applied to a specific example. It is concluded that this formulation and analysis leads to more exact fissile and fusile fuel characterizations than suggested by conventional procedures. </p> / Thesis / Master of Engineering (MEngr)

No description available.

No description available.

Increasing carbon emissions and insecurities in oil supply have led to heightened interest in hydrogen powered fuel cells. Preferably, the cell runs on hydrogen gas, though due to the sensitivity of the catalytic components in the fuel cell to carbon monoxide, the hydrogen must be extremely pure (typically <50 ppm CO). Due to a lack of hydrogen infrastructure, it is envisaged that a medium term solution will be the reforming of more conventional fuels such as gasoline. The gas mixture produced however, contains impurities such as CO, CO₂ and CH₄. Purification may be achieved using palladium membranes, which allow selective permeation of hydrogen. This thesis describes the research carried out in conjunction with Johnson Matthey on thin (typically 7.5 μm) palladium/silver alloy membranes supported on both ceramic and stainless steel porous tubular substrates. Extensive experimental flow testing has been performed to assess the effect of temperature, feed composition, including wet feeds, and membrane thickness on the hydrogen purification properties. An existing Fortran based model was validated and revised to accurately account for the effects of operating conditions such as temperature and carbon monoxide concentration. This work provided excellent correlation between experimental and simulated results. The validated and improved model was incorporated in the design of a hydrogen refuelling station in Aspen Plus and the palladium membrane requirements assessed to supply 650 fuel cell vehicles per day. The system incorporated a steam reformer, membrane clean-up module, water trap and high pressure compressor for hydrogen storage at 1000 bara. Operating conditions such as system pressure, fuel feed and steam to carbon ratio were investigated and adjusted to optimise the overall system efficiency. An efficiency of 52% was achieved with a steam to carbon ratio of SCR = 2.5. A membrane requirement of 6000 standard tubes was found to provide a 90% hydrogen recovery efficiency.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015 / Spent nuclear fuel storage is gradually becoming a nightmare for nuclear reactors which were commissioned in the 1980s. This leaves the nuclear facility management with the dilemma of having to choose between pursuing the cask storage option to relieve the demand pressure on the spent fuel pool, or to opt for the more radical but unpopular option of shutting down the reactor compromising the energy supply, and South Africa is no exception. In a bid to minimise the risk of reactor shut down, the Nuclear Analysis Section (NAS) of Eskom launched the present study of investigating the design requirements of spent fuel casks suitable for the storage and transportation of spent fuel assemblies that have an initial enrichment of up to 5 wt% and much higher burnup of between 50 and 60 GWD/MTU. The aim of the present study is to investigate the suitability of the existing casks for use in 5 wt% enriched fuel, given that they are licensed for a maximum enrichment of 3.5 wt%. As a result of the huge number of casks required, there is potentially a risk of shortage of cask storage space and, therefore, it was prudent that the study also investigates the most optimum storage array that will maximise the storage space, while keeping the effective neutron multiplication factor (keff) below the internationally recommended value of 0.95 [IAEA, 2014]. As such, it is also necessary to identify parameters which have the greatest effect on the neutron multiplication factor. These include determining the effect of changes in moderator and fuel temperature on the neutron multiplication factor and also what the effect of an increase in the concentration in 10B of the boral plate will have on the neutron multiplication factor. / M T 2016

The currently reported work involved fundamental study of auto-ignition under unusually high knock intensities in an optical spark ignition engine. The single cylinder research engine adopted included full bore overhead optical access capable of withstanding continuous peak in-cylinder pressure and knock intensity of up to 150 bar and 60 bar respectively. Heavy knock was deliberately induced under relatively low loads (5 bar IMEP) using inlet air heating up to 66 °C and a primary reference fuel blend of reduced octane rating (75 RON). High speed chemiluminescence natural light imaging was used together with simultaneous heat release analysis to evaluate the combustion events. The key out comes of this study could be listed as follow: • Proof and improved understanding of multi centred auto-ignition events under high KIs • Improved understanding of the potential pitfalls of over-fuelling for heavy knock suppression • Optical validation of 'natural' oil droplet release and on-off behaviour of knocking cycles Multiple centred auto-ignition events were regularly observed to lead in to violent knocking events, with knock intensities above 140 bar observed. The ability to directly image the events associated with such high magnitude of knock is believed to be a world first in a full bore optical engine. The multiple centred events were in good agreement with the developing detonation theory to be the key mechanism leading to heavy knock in modern downsized SI engines. The accompanying thermodynamic analysis indicated lack of relation between knock intensity and the remaining unburned mass fraction burned at the onset of the auto-ignition. Spatial analysis of the full series of images captured demonstrated random location of the first captured auto-ignition sites during developing auto-ignition events. Under such circumstances new flame kernels formed at these sites, with initial steady growth sometimes observed to suppress the growth of the earlier spark initiated main flame front prior to violent end gas auto-ignition. It was found that pre-ignition most commonly initiated in the area surrounding the exhaust valve head and resulted in a deflagration that caused the overall combustion phasing to be over advanced. In the cycles after heavy knock, droplets of what appeared to be lubricant were sometimes observed moving within the main charge and causing pre-ignition. These released lubricant droplets were found to survive within the combustion chamber for multiple cycles and were associated with a corresponding "on-off" knocking combustion pattern that has been so widely associated with super-knock in real downsized spark ignition engines. This research also concerned with improving understanding of the competing effects of latent heat of vaporization and auto-ignition delay times of different ethanol blended fuels during heaving knocking combustion. Under normal operation the engine was operated under port fuel injection with a stoichiometric air-fuel mixture. Additional excess fuel of varied blend was then introduced directly into the end-gas in short transient bursts. As the mass of excess fuel was progressively increased a trade-off was apparent, with knock intensity first increasing by up to 60% before lower unburned gas temperatures suppressed knock under extremely rich conditions (γ=0.66). This trade-off is not usually observed during conventional low intensity knock suppression via over-fuelling and has been associated with the reducing auto-ignition delay times outweighing the influence of charge cooling and ratio of specific heats. Ethanol had the highest latent heat of vaporization amongst the other fuels directly injected and was more effective to reduce knock intensity albeit still aggravating knock under slightly rich conditions. Overall, the results demonstrate the risks in employing excess fuel to suppress knock deep within a heavy knocking combustion regime (potentially including a Super-Knock regime).