Thesis (M. P. A.)--Texas State University-San Marcos, 2009. / "Spring 2009." Includes bibliographical references (leaves 75-79).

Thesis (Ph. D.)--Open University. BLDSC no. DX218866.

Zugl.: Berlin, Freie Univ., Diss., 2003. / With a German abstract. Includes bibliographical references.

Thesis (M. Eng. Sc.)--University of Queensland, 2002. / Includes bibliographical references (p. 141).

Thesis (M. Arch.)--University of Hong Kong, 2001. / Includes special report study entitled: An education and research centre on renewable energy. Includes bibliographical references.

Solar photovoltaic industry is a hot research field, massive attempts are going on all over the world to increase its productivity in different ways. One of the challenges for solar cells is the light spectrum mismatch losses, which referred to the part of solar spectrum that cannot be utilized to electricity by the conventional cells. Two ways have been suggested to overcome solar spectrum mismatch losses, the first is multi layered cells (tandem cells) with a different light behavior for each layer, and the second is spectrum conversion which is this researches subject. Spectral modification or conversion in solar cells industry has been studied and different lab scale models have been introduced. According to nanoscale journal, such technology may be the base of the next generation solar cells, mentioning specifically the use of luminescence down conversion and up conversion techniques to control the light spectrum on the solar cell, these endeavors targets to produce solar cells that is not subjugated to Shockley-Queisser maximum efficiency limit of 31%. This research aims to draw a map of various ideas introduced to incorporate similar technologies in solar cell products, beside further suggestion to enhance its technical behavior and to push the commercialization of the technology forward. This is expected to reveal clear image about technology’s future development map for the upcoming studies, and to create a motivation for further studies towards a commercial production scale. The proposed commercialized model will result in enhancing the maximum theoretical efficiency limit to 48% if all spectral mismatch loses have been eliminated. Quantum energy level diagrams have been illustrated to describe each model’s performance under a theoretical light spectrum.

The field of solar energy conversion has experienced resurgence in recent years due to mounting concerns related to fossil fuel consumption. The sheer quantity of available solar energy and corresponding opportunity for technological improvement has motivated extensive study of novel light-absorbing semiconductors for solar energy conversion. Often, these studies have focused on new ways of synthesizing and altering thin film semiconductor materials with unique compositions and morphologies in order to optimize them for higher conversion efficiencies. In this dissertation, we discuss the synthesis and electrochemical characterization of a variety of candidate semiconductor materials exhibiting promising characteristics for photoelectrochemical solar energy conversion. Three specific methods of thin film deposition are detailed. The first is a physical vapor deposition technique used to independently tune the morphology and composition of hematite (α-Fe2O3) based materials. Because of hematite’s poor electronic properties, these modifications were able to significantly improve its performance as a photoanode for water oxidation. The second technique is electrodeposition, which was employed to deposit the novel ternary metal oxide, CuBi2O4. The study of these films, along with those prepared by physical vapor deposition, provided insight into the factors limiting the ability of this photo-active material to function as a photocathode for hydrogen evolution from water. The third technique is chemical spray pyrolysis, which was employed to deposit and optimize films of the bismuth chalco-halides BiOI and BiSI. These studies were used to obtain previously unknown properties of these materials relevant to their utilization in photoelectrochemical cells. The manipulation of deposition temperature had significant effects on these properties and dictated the films’ overall photoconversion performance. / text

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

Many public and private entities have heavily invested in efficiency measures and renewable sources to generate energy savings and reduce fossil fuel consumption. Private utilities have invested over $4 billion in energy efficiency with 56% of these investments directed towards consumer incentives. However, the magnitude of the expected savings and the effectiveness of the technological measures remain uncertain. Multiple studies attribute the reasons driving these uncertainties to behavioral phenomena such as “the rebound effect.” This work provides insights on the uncertainties generating potential differences between expected and observed performances of demand-side measures (DSM) and distributed generation strategies, using mixed methods that employ both empirical analyses and engineering economics. This study also provides guidelines to stakeholders to effectively use the benefits from DSM strategies towards asset preservation for affordable multifamily houses. Section 2 describes how joint efficiency gains compare to similar singular efficiency gains for single-family households and discusses the implications of these differences. This work provides empirical models of marginal technical change for multiple residential electricity end-uses, including space conditioning technologies, appliances, devices, and electric vehicles. Results indicate that the relative household level of technological sophistication significantly influences the performance of demand-side measures, particularly the presence of a programmable thermostat. As to space conditioning, results demonstrate that sufficient consistent technical improvement leads to net energy savings, which could be due to technical factors or to a declining marginal rebound effect. Section 3 empirically evaluates the performance of distributed residential photovoltaic (PV) solar panels and identifies the technological and demographic factors influencing PV performance and adoption choice. Results show that modeling PV adoption choice significantly impacts the household energy demand, suggesting that the differences in the actual evaluated behavioral responses and the self-reported changes in electricity consumption are more complex than assumed by other studies. The analysis indicates that electricity use decreases marginally for PV adopters if sufficient efficiency improvements in space conditioning are made. Results further imply that households that adopt solar panels might “take back” roughly 24% of the annual electricity production for PV technologies. Section 4 describes replicable engineering economic models for estimating conventional rehabilitation, energy, and water retrofit costs for low-income multi-family housing units. The purpose of this study is to prioritize policy interventions aimed at maintaining property location and use, and to identify the capital investment needs that could be partially provided by local and state housing authorities. Section 5 synthesizes the work, describes the future work, provides guidelines for local and state efficiency program administrators, and insights on prioritizing and designing efficiency interventions. / text