Engineering Commons^™

Chemical And Electronic Structure Of Surfaces And Interfaces In Cadmium Telluride Based Photovoltaic Devices, Douglas Arthur Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The surface and interface properties are of the upmost importance in the understanding, optimization, and application for photovoltaic devices. Often the chemical, electronic, and morphological properties of the films are empirically optimized, however when progress slows, a fundamental understanding of these properties can lead to breakthroughs. In this work, surfaces and interfaces of solar cell-relevant films are probed with a repertoire of X-ray analytical and microanalysis techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), X-ray emission (XES) spectroscopies, and atomic force (AFM) and scanning electron (SEM) microscopies.

Silicon-based devices currently dominate the solar market, which is rather inflexible …

Compounds Released From Biomass Deconstruction: Understanding Their Effect On Cellulose Enzyme Hydrolysis And Their Biological Activity, Angele Djioleu

Graduate Theses and Dissertations

The effect of compounds produced during biomass pretreatment on cellulolytic enzyme was investigated. Liquid prehydrolyzates were prepared by pretreating switchgrass using 24 combinations of temperature, time, and sulfuric acid concentration based on a full factorial design. Temperature was varied from 140°C to 180°C; time ranged from 10 to 40 min; and the sulfuric acid concentrations were 0.5% or 1% (v/v). Identified products in the prehydrolyzates included xylose, glucose, hydroxymethylfurfural (HMF), furfural, acetic acid, formic acid, and phenolic compounds at concentration ranging from 0 to 21.4 g/L. Pretreatment conditions significantly affected the concentrations of compounds detected in prehydrolyzates. When assayed in …

Designing, Building And Testing A Solar Thermoelectric Generation, Steg, For Energy Delivery To Remote Residential Areas In Developing Regions, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

New alternatives and inventive renewable energy techniques which encompass both generation and power management solutions are fundamental for meeting remote residential energy supply and demand today, especially if the grid is quasi-inexistent. Solar thermoelectric generators can be a cost-effective alternative to photovoltaics for a remote residential household power supply. A complete solar thermoelectric energy harvesting system is presented for energy delivery to remote residential areas in developing regions. To this end, the entire system was built, modeled, and then validated with LTspice simulator software via thermal-to-electrical analogy schemes. Valuable data in conjunction with two novel LTspice circuits were obtained, showing …

Water Withdrawal And Consumption Reduction Analysis For Electrical Energy Generation System, Narjes Nouri

Theses and Dissertations

There is an increasing concern over shrinking water resources. Water use in the energy sector primarily occurs in electricity generation. Anticipating scarcer supplies, the value of water is undoubtedly on the rise and design, implementation, and utilization of water saving mechanisms in energy generation systems are becoming inevitable. Most power plants generate power by boiling water to produce steam to spin electricity-generating turbines. Large quantities of water are often used to cool the steam in these plants. As a consequence, most fossil-based power plants in addition to consuming water, impact the water resources by raising the temperature of water withdrawn …

Investigation Of Electrolyte Wetting In Lithium Ion Batteries: Effects Of Electrode Pore Structures And Solution, Yangping Sheng

Theses and Dissertations

Beside natural source energy carriers such as petroleum, coal and natural gas, the lithium ion battery is a promising man-made energy carrier for the future. This is a similar process evolved from horse-powered era to engine driven age. There are still a lot of challenges ahead like low energy density, low rate performance, aging problems, high cost and safety etc.

In lithium ion batteries, investigation about manufacturing process is as important as the development of material. The manufacturing of lithium ion battery, including production process (slurry making, coating, drying etc.), and post-production (slitting, calendering etc.) is also complicated and critical …

Operation And Monitoring Of Parabolic Trough Concentrated Solar Power Plant, Harsha Vardhan Amba

USF Tampa Graduate Theses and Dissertations

The majority of the power generated today is produced using fossil fuels,emitting carbon dioxide and other pollutants every second. Also, fossil fuels will eventually run out. For the increasing worldwide energy demand, the use f reliable and environmentally beneficial natural energy sources is one of the biggest challenges. Alongside wind and water, the solar energy which is clean, CO2-neutral and limitless, is our most valuable resource.

Concentrated solar power (CSP) is becoming one of the excellent alternative sources for the power industry. The successful implementation of this technology requires the efficient design of tracking and operation system of the CSP …

Bio-Photoelectrochemical Solar Cells Incorporating Reaction Center And Reaction Center Plus Light Harvesting Complexes, Houman Yaghoubi

USF Tampa Graduate Theses and Dissertations

Harvesting solar energy can potentially be a promising solution to the energy crisis now and in the future. However, material and processing costs continue to be the most important limitations for the commercial devices. A key solution to these problems might lie within the development of bio-hybrid solar cells that seeks to mimic photosynthesis to harvest solar energy and to take advantage of the low material costs, negative carbon footprint, and material abundance. The bio-photoelectrochemical cell technologies exploit biomimetic means of energy conversion by utilizing plant-derived photosystems which can be inexpensive and ultimately the most sustainable alternative. Plants and photosynthetic …

Research On The Application Of Solar Photovoltaic System On Large Ocean-Going Ships, Wanhe Huang

Maritime Safety & Environment Management Dissertations (Dalian)

No abstract provided.

Tin Nanoparticles Encapsulated In Hollow Tio2 Spheres As High Performance Anode Materials For Li-Ion Batteries, Xiang Pan

Theses and Dissertations

Tin, an anode material with a high capacity for lithium-ion batteries, has poor cyclic performance because of the high volume expansion upon lithiation. Based on a literature review of the applications of lithium-ion batteries and current research progress of the tin-based anode materials for lithium-ion batteries, we developed a method to synthesize hollow TiO2 spheres with tin nanoparticles anchored on the inner surface of the TiO2 shell. Such a unique tin/TiO2 composite alleviates the volume change of tin–based anode materials in charge-discharge processes. SnCl2·2H2O (Tin (II) chloride dihydrate) and titanium (IV) isopropoxide (TIPT) were used as the Sn source and …

Integrated Li-Ion Ultracapacitor With Lead Acid Battery For Vehicular Start-Stop, Emad Manla

Theses and Dissertations

Advancements in automobile manufacturing aim at improving the driving experience at every level possible. One improvement aspect is increasing gas efficiency via hybridization, which can be achieved by introducing a feature called start-stop. This feature automatically switches the internal combustion engine off when it idles and switches it back on when it is time to resume driving. This application has been proven to reduce the amount of gas consumption and emission of greenhouse effect gases in the atmosphere. However, the repeated cranking of the engine puts a large amount of stress on the lead acid battery required to perform the …

Synthesis Of Palladium And Palladium-Copper Nanostructures As Electrocatalysts, Haibin Wu

Graduate Theses and Dissertations

Pd and its alloys are alternatives of Pt as promising catalysts and electrocatalysts for many reactions. Size controlled synthesis of nanoparticles remains a major research subject, since smaller size particles show better catalytic performance. In this work, we developed a modified chemical wet method to prepare Pd and Pd-Cu nanostructures with uniform small size. Different sizes and shapes of Pd nanostructures were successfully synthesized by using the two reducing agents (i.e., L-ascorbyl-6-palmitate or phenylphosphinic acid). The reducing agents play a role to control the final morphologies and sizes of particles. The use of L-ascorbyl-6-palmitate favors to form irregular branch shapes …

Virtual Droop Control Framework And Stability Analyses For Microgrids With High Penetration Of Renewables, Ashishkumar Kanubhai Solanki

Theses and Dissertations

Microgrids can provide the most promising means of integrating large amounts of distributed sources into the power grid and can supply reliable power to critical loads. However, managing distributed sources and loads within a microgrid during island and grid-tie modes and during transitions is a challenge. Stable operation of a microgrid is a concern specifically during the starting of motor loads, switching of large loads, and in presence of high penetration of renewable resources. Hence, a generalized control framework is required to regulate microgrid voltage and frequency, maintain power quality, manage Distributed Generations (DG) and ensure microgrid stability. Several control …

Computational And Experimental Study On Innovative Horizontal-Axis Wind Turbine Blade Designs, Abdulrahman A. Alsultan

Theses and Dissertations

This study was made to explore three novel blade geometries with intent to increase power production of a horizontal axes, three blade arrangement wind turbine. This was done by designing the blades using computer aided design (CAD) modeling software, followed by a rigorous testing phase, utilizing a computational fluid dynamics software (CFD). The blades then went into a cycle of iterative design to achieve the best parameters that will positively impact the overall power generation efficiency. These steps were followed by printing the blades utilizing 3D Printing technology, testing them for the power generation, and finally, tabulating these findings to …

Experimental Verification And Integration Of A Next Generation Smart Power Management System, Tavis Clemmer

Graduate Theses and Dissertations

With the increase in energy demand by the residential community in this country and the diminishing fossil fuel resources being used for electric energy production there is a need for a system to efficiently manage power within a residence. The Smart Green Power Node (SGPN) is a next generation energy management system that automates on-site energy production, storage, consumption, and grid usage to yield the most savings for both the utility and the consumer. Such a system automatically manages on-site distributed generation sources such as a PhotoVoltaic (PV) input and battery storage to curtail grid energy usage when the price …

Incorporating Environmental And Social Factors Into Decision-Making Of An Oil And Gas Industry To Improve Sustainability, Gaurav Dabhadkar

Graduate Theses and Dissertations

The energy industry (including the oil and gas industry) is facing unparalleled scrutiny and demands from stakeholders including investors, regulators (industry and environmental), communities, and other stakeholders. Sustainable development is one of the major concerns of the oil and gas industry. Companies are seeking to increase sustainability of their operations by considering environmental and Social concerns in addition to economic concerns. Oil and gas companies need to take decisions at different stages of the product life cycle (e.g. planning, design, exploration, production, and clean-up) which have direct or indirect impact on the organization's objectives. Addressing economic, technical, Social, and environmental …

Top-Down Aluminum Induced Crystallization For Photovoltaics, Seth Daniel Shumate

Graduate Theses and Dissertations

Passivating silicon solar cell surfaces is critical to fabricating very high efficiency and low cost photovoltaic devices. The sun-facing surface of the solar cell, known as the emitter, is particularly important when designing a solar cell. This work focused first on an alternative method of forming the emitter of silicon solar cells, and secondly on a method for improving the surface passivation of both these non-traditional and standard n-type solar cells.

Top-down aluminum induced crystallization (TAIC) was used for forming a polycrystalline silicon layer from amorphous silicon using aluminum to catalyze the crystallization at much lower temperatures than otherwise possible. …

Enhancement Of The Performance Of Gaas Based Solar Cells By Using Plasmonic, Anti-Reflection Coating And Hydrophobic Effects, Yahia Fayiz Makableh

Graduate Theses and Dissertations

Investigation of renewable energy resources is gaining huge momentum in recent years due to the limited fossil fuels, and their detriment impact on the environment. Solar energy is promising to meet the increased energy demand. In order to achieve this goal, solar energy has to be harvested efficiently at low cost. Therefore, higher efficiency solar cells are the primary focus of research worldwide. Photovoltaics based on InAs/GaAs intermediate band solar cells and their device performance enhancements are investigated in this dissertation. The device enhancement is carried out by surface modification methods. The dissertation work is inspired by the need of …

Transformation Of Swine Manure And Algal Consortia To Value-Added Products, Mahmoud A. Sharara

Graduate Theses and Dissertations

The swine production sector is projected to grow globally. In the past, this growth manifested itself in increased herd sizes and geographically concentrated production. Although economically sound, these trends had negative consequences on surrounding ecosystems. Over-application of manure resulted in water quality degradation, while long-term storage of manure slurries was found to promote release of potent GHG emissions. There is a need for innovative approaches for swine manure management that are compatible with current scales of production, and increasingly strict environmental regulations.

This study aims to investigate the potential for incorporating gasification as part of a novel swine manure management …

Applying The Analytic Hierarchy Process To Oil Sands Environmental Compliance Risk Management, Izak Johannes Roux

Walden Dissertations and Doctoral Studies

Oil companies in Alberta, Canada, invested $32 billion on new oil sands projects in 2013. Despite the size of this investment, there is a demonstrable deficiency in the uniformity and understanding of environmental legislation requirements that manifest into increased project compliance risks. This descriptive study developed 2 prioritized lists of environmental regulatory compliance risks and mitigation strategies and used multi-criteria decision theory for its theoretical framework. Information from compiled lists of environmental compliance risks and mitigation strategies was used to generate a specialized pairwise survey, which was piloted by 5 subject matter experts (SMEs). The survey was validated by a …

Advanced Computational Modeling Of The Internal Structure Of Smart Wind-Turbine Blades, Sanket Seetaram Bhogle

Dissertations, Master's Theses and Master's Reports - Open

Implementation of stable aeroelastic models with the ability to capture the complex features of Multi concept smartblades is a prime step in reducing the uncertainties that come along with blade dynamics. The numerical simulations of fluid structure interaction can thus be used to test a realistic scenarios comprising of full-scale blades at a reasonably low computational cost.

A code which was a combination of two advanced numerical models was designed and was run with the help of paralell HPC supercomputer platform. The first model was based on a variation of dimensional reduction technique proposed by Hodges and Yu. This model …

The Use Of Jatropha Curcas To Achieve A Self Sufficient Water Distribution System: A Case Study In Rural Senegal, Alexandra Archer

Dissertations, Master's Theses and Master's Reports - Open

The use of Jatropha curcas as a source of oil for fueling water pumps holds promise for rural communities struggling to achieve water security in arid climates. The potential for use in developing communities as an affordable, sustainable fuel source has been highly recommended for many reasons: it is easily propagated, drought resistant, grows rapidly, and has high-oil-content seeds, as well as medicinal and economic potential. This study uses a rural community in Senegal, West Africa, and calculates at what level of Jatropha curcas production the village is able to be self-sufficient in fueling their water system to meet drinking, …

A Computational Study Of A Photovoltaic Compound Parabolic Concentrator, William M. Vance

Browse all Theses and Dissertations

Routines have been written and added to the Wright State developed solar system simulation program called Solar_PVHFC to model incident solar radiation for a compound parabolic concentrator (CPC) that uses solar panels (photovoltaic panels) to produce electrical energy. Solar_PVHFC is a program that models a solar energy system composed of solar panels to produce electricity from the sun, hydrogen storage tanks to chemically store the energy produced by the solar panels, and fuel cells to convert between electrical and chemical energy when required. Solar_PVHFC features several adjustable parameters to model a solar panel, hydrogen storage, and fuel cell system. Now …

Novel Endohedral Derivatives Of Sc3n@C2n (N = 34, 40) And Unique Tether Controlled Bis-Functionalization Of Fullerenes, Maira Raquel Ceron Hernandez

Open Access Theses & Dissertations

Since the discovery of fullerenes in 1985, their exohedral functionalization has been necessary to increase their solubility and explore their properties and potential applications in materials science and medicinal chemistry. This Thesis provides a short overview of the importance of electronic, size and shape complementarity in determining the structures of specific endohedral fullerene compounds. This is followed by a description of a new method for the separation of scandium nitride endohedral fullerenes Sc3N@C2n (n = 34, 39 and 40), and their monofunctionalization.

We also present the regioselective synThesis of easily isolable bis-derivatives of C60, C70, and M3N@Ih-C80 (M = Sc, …

Processing And Property Evaluation Of Tungsten-Based Mixed Oxides For Photovoltaics And Optoelectronics, Mirella Vargas

Open Access Theses & Dissertations

Tungsten Oxide (WO3) films and low-dimensional structures have proven to be promising candidates in the fields of photonics and electronics. WO3 is a well-established n-type semiconductor characterized by unique electrochromic behavior, an ideal optical band gap that permits transparency over a wide spectral range, and high chemical integrity. The plethora of diverse properties endow WO3 to be highly effective in applications related to electrochromism, gas sensing, and deriving economical energy. Compared to the bulk films, a materials system involving WO3 and a related species (elements or metal oxides) offer the opportunity to tailor the electrochromic response, and an overall enhancement …

Study Of A Directly Heated Oxy-Fuel Supercritical Power Generation System, A S M Arifur Rahim Chowdhury

Open Access Theses & Dissertations

The Directly heated supercritical oxy-fuel gas turbines have the potential to become an important addition to current power generation systems. They provide a higher thermal efficiency and more effective carbon capture techniques than existing gas turbines. Due to the higher density of the working fluids, the turbomachinery size in these systems can be reduced significantly; this will facilitate to minimize the operational cost. To achieve supercritical working fluid at the turbine inlet combustion needs to be conducted under enormous amounts of pressure; these values are is about 10 times those found in the present gas turbines. Additionally, existing material operational …

Analysis Of Carbon Policies For Electricity Networks With High Penetration Of Green Generation, Felipe Feijoo

USF Tampa Graduate Theses and Dissertations

In recent decades, climate change has become one of the most crucial challenges for humanity. Climate change has a direct correlation with global warming, caused mainly by the green house gas emissions (GHG). The Environmental Protection Agency in the U.S. (EPA) attributes carbon dioxide to account for approximately 82\% of the GHG emissions. Unfortunately, the energy sector is the main producer of carbon dioxide, with China and the U.S. as the highest emitters. Therefore, there is a strong (positive) correlation between energy production, global warming, and climate change. Stringent carbon emissions reduction targets have been established in order to reduce …

Achieving Reliable Generation \& Delivery Of Energy Through Robust Optimization, Anna Danandeh

USF Tampa Graduate Theses and Dissertations

In this dissertation, we elaborate on the inherent risks and uncertainties in power systems and associated industries, and develop practical solution methods to eliminate their adverse effects.

our research agenda consists of practice-driven problems in different stages of power generation as follows. (1) Affordable fuel procurement through developing a comprehensive fuel supply chain design and operations planning system for electricity generation companies, (2) reliable electricity generation through incorporating dynamic asset rating concept in the unit commitment problem, and (3) efficient demand management through proposing a job scheduling model for effective local generation consumption.

Since reliability cannot be compromised in energy …

Single And Multiple Objective Biomass-To-Biofuel Supply Chain Optimization Considering Environmental Impacts, Claudia Evangelina Valles Sosa

Open Access Theses & Dissertations

Bioenergy has become an important alternative source of energy to alleviate the reliance on petroleum energy. Bioenergy offers diminishing climate change by reducing Green House Gas Emissions, as well as providing energy security and enhancing rural development. The Energy Independence and Security Act mandate the use of 21 billion gallons of advanced biofuels including 16 billion gallons of cellulosic biofuels by the year 2022. It is clear that Biomass can make a substantial contribution to supply future energy demand in a sustainable way. However, the supply of sustainable energy is one of the main challenges that mankind will face over …

Experimental Investigation Of Encapsulated Phase Change Materials For Thermal Energy Storage, Tanvir E. Alam

USF Tampa Graduate Theses and Dissertations

Thermal energy storage (TES) is one of the most attractive and cost effective solutions to the intermittent generation systems like solar, wind and other renewable sources, compared to alternatives. It creates a bridge between the power supply and demand during peak hours or at times of emergency to ensure the continuous supply of energy. Among all the TES systems, latent heat thermal energy storage (LHTES) draws lots of interests as it has high energy density and can store or retrieve energy isothermally. Two major technical challenges associated with the LHTES are low thermal conductivity of the phase change materials (PCMs), …

High Temperature Helical Tubular Receiver For Concentrating Solar Power System, Nazmul Hossain

Open Access Theses & Dissertations

In the field of conventional cleaner power generation technology, concentrating solar power systems have introduced remarkable opportunity. In a solar power tower, solar energy concentrated by the heliostats at a single point produces very high temperature. Falling solid particles or heat transfer fluid passing through that high temperature region absorbs heat to generate electricity. Increasing the residence time will result in more heat gain and increase efficiency. A novel design of solar receiver for both fluid and solid particle is approached in this paper which can increase residence time resulting in higher temperature gain in one cycle compared to conventional …