Physical Sciences and Mathematics Commons^™

Wind Turbine Controls For Farm And Offshore Operation, Zhongzhou Yang

Theses and Dissertations

Development of advanced control techniques is a critical measure for reducing the cost of energy for wind power generation, in terms of both enhancing energy capture and reducing fatigue load. There are two remarkable trends for wind energy. First, more and more large wind farms are developed in order to reduce the unit-power cost in installation, operation, maintenance and transmission. Second, offshore wind energy has received significant attention when the scarcity of land resource has appeared to be a major bottleneck for next level of wind penetration, especially for Europe and Asia. This dissertation study investigates on several wind turbine …

The Water Wall: A Passive Solar Collection And Thermal Storage Device For Supplementary Radiant Heating, Rhett Roman Noseck

UNLV Theses, Dissertations, Professional Papers, and Capstones

Through the implementation of passive solar building systems, suburbia could take a fresh new step forward toward a progressively more sustainable direction. Making passive solar strategies a priority, master planned community developments would see opportunity to change the style and design of future suburban residences.

The focus and intention of this body of work is to research, design, fabricate, and test a prototype of a passive solar heating device using water as the medium for thermal storage. The size and shape of the design for the water wall device will be determined by the currently built suburban environment; however, for …

Criticality And Characteristic Neutronic Analysis Of A Transient-State Shockwave In A Pulsed Spherical Gaseous Uranium-Hexafluoride Reactor, Jeremiah Boles

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to analyze the theoretical criticality of a spherical uranium-hexafluoride reactor with a transient, pulsed shockwave emanating from the center of the sphere in an outward-radial direction. This novel nuclear reactor design, based upon pulsed fission in a spherical enclosure is proposed for possible use in direct energy conversion, where the energy from fission products is captured through the use of electrostatic fields or through induction. An analysis of the dynamic behavior of the shockwave in this reactor is the subject of this thesis. As a shockwave travels through a fluid medium, the characteristics of …

Hydrogeological And Thermal Sustainability Of Geothermal Borehole Heat Exchangers, S. Emad Dehkordi

Electronic Thesis and Dissertation Repository

Assessment of the current approach taken by guidelines and design methods of vertical closed loop heat exchangers shows that often groundwater flow is either disregarded or is not methodically incorporated. The state of scientific research in this arena reveals that overlooking the groundwater flow in the design procedure may not always be a correct assumption. The significance of advective heat transport compared to conduction is defined by the groundwater flux or Darcy velocity which heavily depends on the hydraulic conductivity of the ground, followed by the hydraulic gradient which has a relatively limited range. A sensitivity analysis on ground and …

Environmental Tradeoffs In Bioenergy Production And Agricultural Practices, Alicia Lynn English

Open Access Dissertations

The focus of this dissertation is the environmental tradeoffs of stover removal within the Corn Belt. The environmental tradeoffs considered are mainly concerned with managing soil erosion and soil quality. The analysis layers soil characteristics, management strategies and per acre costs using an integrated RUSLE2/WEPS model and an economic optimization model to illuminate a lower bound supply response. Different assumptions were tested in regards to sustainability, prices, and market integration for five states and 18,760 soil types throughout the Corn Belt. Sustainability was defined to limit soil erosion from wind and water to 5 tons/acre/year and the soil organic matter …

Electric Machine Differential For Vehicle Traction Control And Stability Control, Sandun Shivantha Kuruppu

Open Access Dissertations

Evolving requirements in energy efficiency and tightening regulations for reliable electric drivetrains drive the advancement of the hybrid electric (HEV) and full electric vehicle (EV) technology. Different configurations of EV and HEV architectures are evaluated for their performance. The future technology is trending towards utilizing distinctive properties in electric machines to not only to improve efficiency but also to realize advanced road adhesion controls and vehicle stability controls. Electric machine differential (EMD) is such a concept under current investigation for applications in the near future. Reliability of a power train is critical. Therefore, sophisticated fault detection schemes are essential in …

Redefining The Operation And Design Considerations Of Organic Solar Cells: Role Of Morphology And Defect States, Biswajit Ray

Open Access Dissertations

Organic photovoltaic (OPV) technology is currently a topic of great interest for potentially low cost solar energy conversion and possibility of many novel PV applications (e.g., building-integrated PV, portable solar cells). Successful commercialization of this technology, however, will require significant improvement in efficiency and lifetime. In the last few years, innovation in novel polymer synthesis has raised the efficiency of OPV above 10%, at par with a-Si and earth-abundant solar cells. Further improvement in performance relies on breakthroughs in device design, which requires profound understanding of the physics of device operation. A major challenge in the design of the state …

Solar Cell Temperature Dependent Efficiency And Very High Temperature Efficiency Limits, John Robert Wilcox

Open Access Dissertations

Clean renewable solar energy is and will continue to be a critically important source of electrical energy. Solar energy has the potential of meeting all of the world's energy needs, and has seen substantial growth in recent years. Solar cells can convert sun light directly into electrical energy, and much progress has been made in making them less expensive and more efficient. Solar cells are often characterized and modeled at 25 °C, which is significantly lower than their peak operating temperature. In some thermal concentrating systems, solar cells operate above 300 °C. Since increasing the temperature drastically affects the terminal …

Energy Systems Analysis For A Solar Economy, Dharik Sanchan Mallapragada

Open Access Dissertations

The use of solar energy for human needs faces challenges owing to its relatively low energy intensity and intermittent availability, coupled with the constrained availability of renewable carbon and land resources. This study uses systems analysis tools to identify carbon and energy efficient transformations of solar energy for different purposes, including transportation fuels and grid-scale energy storage. These efforts have been complemented with a feasibility analysis of existing fossil-energy and other hybrid pathways.

In an era of limited fossil resources, liquid fuels from sustainably available (SA) biomass could meet the energy needs of the transportation sector. We present a method …

An Experimental Investigation Of Wind Turbine Aerodynamic Interaction, Brandon Lee Ennis

Open Access Dissertations

Wind turbines have become a viable component in the overall energy makeup of the United States due to improved economics where energy prices have risen and production costs dropped. For a fixed cost, the effectiveness of a wind turbine financially is highly related to its performance. Considering the size of current wind farms, a minor performance improvement will result in large additional sums of revenue. A problem that has received attention with wind farms is that while the fixed costs of the development do get spread out further to reduce the installed cost of each wind turbine, the wind turbines …

An Analysis Of The Impact Of Storage Temperature, Moisture Content & Duration Upon The Chemical Components & Bioprocessing Of Lignocellulosic Biomass, Arun Athmanathan

Open Access Dissertations

The successful utilization of lignocellulosic biomass as a feedstock for fuels and chemicals necessitates storage for 2-6 months. It is correspondingly important to understand the impact of storage parameters - moisture concentration, temperature and duration - on biomass quality.

As aerobic storage is the most viable large-scale solution, aerobic storage experiments were carried out with three projected bioenergy feedstocks - sweet sorghum (Sorghum bicolor) bagasse, corn (Zea mays) stover and switchgrass (Panicum virgatum). Stored samples of each were examined for dry matter loss and composition change to develop a material balance around carbohydrates and lignin.

A mean dry matter loss …

Technology Agnostic Analysis And Design For Improved Performance, Variability, And Reliability In Thin Film Photovoltaics, Sourabh Dongaonkar

Open Access Dissertations

Thin film photovoltaics (TFPV) offer low cost alternatives to conventional crystalline Silicon (c-Si) PV, and can enable novel applications of PV technology. Their large scale adoption however, requires significant improvements in process yield, and operational reliability. In order to address these challenges, comprehensive understanding of factors affecting panel yield, and predictive models of performance reliability are needed. This has proved to be especially challenging for TFPV for two reasons in particular. First, TFPV technologies encompass a wide variety of materials, processes, and structures, which fragments the research effort. Moreover, the monolithic manufacturing of TFPV modules differs significantly from that of …

Sustainable Development Of Tajikistan: Perspectives For Tajik Aluminum Company (Talco), Tahmina Azizova

Capstone Collection

Energy efficiency is one the most pressing objectives of the XXI century. Energy efficiency is an intrinsic part of sustainable development of any country. But it is especially crucial for country like Tajikistan, which has an inefficient energy use pattern as a result of the legacy of Soviet era. Energy resources required for economic development can be obtained not only through increased extraction of raw materials, but also through improved energy efficiency at the demand side. Tajikistan imports about 35 percent of its energy needs, which makes the country extremely energy-dependent. That leads to an obvious inference that for Tajikistan …

Hydrogen Generation From Magnesium Hydride By Using Organic Acid, Yen-Hsi Ho

Theses and Dissertations

In this paper, the hydrolysis of solid magnesium hydride has been studied with the high concentration of catalyst at the varying temperature. An organic acid (acetic acid, CH3COOH) has been chosen as the catalyst. The study has three objectives: first, using three different weights of MgH2 react with aqueous solution of acid for the hydrogen generation experiments. Secondly, utilizing acetic acid as the catalyst accelerates hydrogen generation. Third, emphasizing the combination of the three operating conditions (the weight of MgH2, the concentration of acetic acid, and the varying temperature) influence the amount of hydrogen generation. The experiments results show acetic …

A Gis-Based Multi-Objective Optimization Of A Lignocellulosic Biomass Supply Chain: A Case Study In Tennessee, Zidong Wang

Masters Theses

To achieve an economically and environmentally sustainable lignocellulosic biomass (LCB)-based biofuel industry sector, the design and location of a sustainable LCB supply chain is important. In this study, a multi-objective optimization model integrated with high-resolution geographical data was developed to examine the optimal switchgrass supply chain for a potential biorefinery in Tennessee, specifically evaluating the potential tradeoffs between the objectives of minimizing plant-gate cost and GHG emissions from the switchgrass supply chain. The key findings of this study are as follows: both plant-gate feedstock cost and GHG emissions were sensitive to the type of land converted into switchgrass production, the …

Market Mechanisms And Price Volatility In New York Electricity Markets, Kimberly Blecich

Honors Theses

The past two decades have born witness to a cascade of new legislation and market design measures to restructure the United States’ electric power industry from price-setting regulatory agencies to competitive markets. Deregulation was intended to increase competition and improve market efficiency while preserving the reliability of the transmission system. Results have varied in success, and deregulation has invariably led to an increase in both the overall price level of electricity and volatility of those prices. Investigating these deregulation consequences is crucial for market operations and retrospective analyses of deployed mechanism outcomes. The objective of this study is to extend …

A Cross-Country Analysis Of Energy Efficient Development, Nicholas Fleagle

Honors Theses

Maximizing energy efficiency, producing as much as possible with as little energy as possible, is something every country should be working toward. This study measures the efficiency of specific countries by examining the interrelationships that exist among each country’s energy consumption and such measures of development as health, education, income, access to essentials and CO2 emissions. It then analyses why certain countries are more efficient than others and how these inefficient countries can improve. Data Envelopment Analysis (DEA) is used to generate a cross country comparison of energy efficiency scores over multiple dimensions of development. Pairs of inefficient countries and …

Hydraulic Fracturing Wastewater: Treatment Methods For Flowback And Produced And Water, Claire Cummins

Honors Theses

In order to prevent groundwater contamination that could potentially put millions of human’s health at risk, as well as billions of the federal government’s money on solving the problem, hydraulic fracturing needs to be heavily regulated. This will ensure that hydrofracking is being done in an environmentally responsible way by every natural gas drilling company and not just those who are willing to pay extra for systems and treatment methods that are more expensive but also more effective. The technology for treating hydrofracking wastewater has not been fully developed and would be used a lot more widely throughout the industry …

An Analysis Of Horizontal Gas Drilling And Its Impact On Spot Market Pricing: A Focus On The Marcellus Shale Production Potential, Samuel O'Connell

Honors Theses

This paper attempts to quantify how the rapid increase in shale gas production in the past fifteen years has impacted regional natural gas spot prices. This method of natural gas extraction-pumping water mixed with sand and clay first vertically and then horizontally, with clay and sand particulates holding fractures open to allow the flow of natural gas-has a shorter well lifespan and faster decline rate than conventional wells. Through analyzing the degree of market integration between shale gas production and spot prices, we can quantify what impact different shale plays have had on the regional pricing of natural gas. With …

Impact Of The Keystone Xl Pipeline On North American Crude Oil Prices, Shawn Ian Stuart

Honors Theses

This paper determines the economic impact of the TransCanada Keystone XL pipeline project. As the Keystone XL pipeline is extremely controversial it is beneficial to determine the impact on North American crude oil prices. Determining the economic impact the Keystone XL pipeline will have on crude oil prices will be a large detriment of whether the pipeline is economically beneficial. By using spot crude prices from different regions around North America and adding capacity of crude oil transmission from western Canada to southeast United States this paper determines the changes in regional spot crude oil prices. As the economic conditions …

Extending Technology Roadmap Through Fuzzy Cognitive Map-Based Scenarios: The Case Of The Wind Energy Sector Of Pakistan, Muhammad Amer

Dissertations and Theses

In this modern era, energy is a key element required for sustainable development and prosperity of a society. Pakistan is an energy deficient country facing problems due to the shortage of over 4000 MW of electricity. The national energy sector is heavily dependent on imported fossil-fuel resources. The energy crisis is negatively affecting all economic and business activities, and it is widely recognized as a severe obstacle to growth and poverty reduction in the country. Establishment of wind farms can help to overcome the energy crisis.

In this research, a national level wind energy roadmap is developed through scenario planning. …

A System Dynamics Analysis Of The Growth In Virginia's Residential Electricity Consumption Trends, 1980-2010., Raguram Sellakkannu

Masters Theses, 2010-2019

Residential electricity consumption in the Commonwealth of Virginia has more than doubled in three decades, between 1980 and 2010. Per capita and per household consumption rates have grown faster than many other states including New York and California. The following dissertation applies systems dynamics methodology to explore the causes of growth in Virginia’s per capita and per household residential electricity consumption rates in relative contrast to New York and California over the past several decades. Major databases used in the study were accessed from the United States Energy Information Administration and the Census Bureau. Qualitative modelling applying system dynamics principles …

Dc Microgrid Modeling And Energy Storage Placement To Enhance System Stability, Carl Westerby

Theses and Dissertations

The work of this thesis represents a joint venture between the University of Wisconsin-Milwaukee and the University of Wisconsin-Madison. A DC microgrid is selected for the efficiency benefits, lack of reactive power in the system, and ease of connecting to an AC grid. The system modeling relies on physical parameters and industry standard methods for the estimation of loads and lines. An example model is created for the University of Wisconsin - Milwaukee's Campus. Due to the high penetration of renewable energy sources in the example model, system stability is a concern. To help mitigate stability issues, analysis is performed …

Experimenting With Polymer Blend Solar Cells And Active Layer Thickness, Ryan Blumenthal

Physics

Bulk heterojunction organic photovoltaics utilize the electrical characteristics of semi-conductive polymers. These solution processable materials are beneficial because of their low material cost, light weight, and simple fabrication requirements. Our devices employ multiple photoactive polymers, P3HT and PCPDTBT, to absorb photons over a wide spectral range. We optimized various device characteristics including thickness and thermal anneal usage to reach a power conversion efficiency of 3.0% in AM1.5 sunlight. Device performance degrades over time due to atmospheric water and oxygen, prompting us to investigate device packaging to extend cell lifetime for additional testing.

Low Turbulence Wind Tunnel Design And Wind Turbine Wake Characterization, Andrew Welsh

Theses and Dissertations

As the prevalence of wind turbines in the energy market increases, so too does the demand for high-wind real-estate. As a result, wind turbines are placed closer together, which leads to structural challenges due to the cyclical fatigue loading from the wake of upwind turbines. Characterizing the wake behind wind turbines with respect to those downwind is especially important given the 20-year wind turbine lifetime that commercial wind turbine consumers expect. This project aimed to characterize the near wake behind a model wind turbine.

In order to accomplish this, a 12.8 meter-long and 1.22 meter-square test section low-turbulence wind tunnel …

Floatovoltaics: Quantifying The Benefits Of A Hydro-Solar Power Fusion, Abe Mckay

Pomona Senior Theses

To slow climate change, humans should take immediate and widespread action. One way to slow climate change is by switching to switch to renewable power plants such as solar fields. Recently, pioneering companies have built solar fields on water bodies. This study found that such a pairing of water and solar could increase production efficiency by 8-10% through panel cooling, save millions of liters of water from evaporation, and produce energy with under-utilized space.

A Policymaker's Guide To Feed-In Tariffs: Encouraging A Responsible Transition To Renewable Electricity In California, Roland P. Thayer

Pomona Senior Theses

The feed-in tariff is a flexible, yet effective mechanism in promoting the proliferation of renewable electricity in California. The tariff creates a stable investment environment that protects both the utilities and the renewable electricity generators. Not only does the system foster capacity growth, but also technological advancement to the point where renewable electricity can compete in the market without assistance. From an environmental standpoint, the feed-in tariff contributes significantly towards achieving the emissions reduction goals set forth by AB32 without causing harmful increases to electricity prices.

The feed-in tariff model has been used in countries all over the world and …

Oil, Oil, Everywhere: Environmental And Human Impacts Of Oil Extraction In The Niger Delta, Julia Pitkin

Pomona Senior Theses

Oil extraction in Nigeria has caused extensive environmental degradation and health problems in many Nigerian communities, particularly in the ecologically sensitive Niger Delta where nearly all of the oil extraction takes place. The reasons for this are complex and have roots in Nigeria’s colonial past. The Nigerian economy is largely reliant on its petroleum resources which, in conjunction with governmental corruption and high international demand for Nigerian oil, has created a system where environmental externalities are largely ignored. Multinational oil companies with little stake in the development and environment of Nigeria are responsible for most of the extraction projects and …

Investigation Of Peak Load Reduction Strategies In Residential Buildings In Cooling Dominated Climates, Fady Atallah

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation of peak load reduction strategies in residential buildings contributes to the global international efforts in reducing energy consumption and is related directly to energy efficiency in residential and commercial buildings. Work reported here involves computer aided building energy simulation of energy efficient and non-energy efficient residential homes coupled with empirical energy consumption data gathered from monitoring an array of energy efficient residential homes. The latter have been implemented for peak load reduction strategies. In addition non-energy efficient residential homes have been monitored to compare performance to the energy efficient homes. This study demonstrates the crucial importance of energy …

Predicting The Performance Of A Solar Domestic Water Heating System With Evacuated Tube Collectors And Hydronic Radiant Flooring, Kimberly Nicole Hammer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Residential solar thermal system installations have been significantly increasing in the last decade and there exists limited resources for reasonably predicting the performance of those systems. A simulated model is developed in MATLAB® and used to predict the performance of a solar domestic water heating system. In the simulated system, hot water is generated using evacuated tube solar collectors and stored in a domestic hot water storage tank, which utilizes immersed coil heat exchangers. The system is designed to provide hydronic radiant floor heating to its occupants based on the heat loss of a building energy model for an energy-efficient …