Browsing by Subject "Solar energy"
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Item À qui le soleil : how Morocco’s developing solar capacities have altered urban infrastructural provisions(2015-12) Rowlinson, Thomas Edmond; Liedl, Petra, 1976-; Wilson, Patricia AnnThe creation of a sustainable, solar-based energy sector in Morocco involves changes to both its domestic energy infrastructure as well as the surrounding political and financial arrangements. This research shows that such changes affect Morocco’s most vulnerable urban citizens, specifically those without current grid service, or hacked grid service: those who live in bidonvilles, or shantytowns and slums. I trace such changes in Morocco’s solar energy to the perpetuation of neocolonial narratives of European energy and historical uses of infrastructure in urban manifestations of colonialism. With a focus on domestic large-scale solar energy generation systems like the publicly-operated MASEN, as well as international, public-private enterprises such as Desertec (a German-Moroccan partnership that is mega-regional in scope), this thesis assesses the level of access afforded to bidonville citizens in Morocco’s biggest city, Casablanca. I offer some ideas on how the flexibility and accessibility in the scale and operation of solar can provide generation capacities to urban citizens living in informal communities.Item A solar adsorption cooling system: an analytical and experimental study(Texas Tech University, 1977-08) Thongprasert, ManitNot availableItem Item Item Computer based data processing system for the Crosbyton Solar Power Project(Texas Tech University, 1981-12) Chao, Shih-ChengThe objective of this study is to establish a Data Processing System to monitor system operation performance during test and changing weather conditions and support the ADVS performance simulation and other applications. This Data Processing System was separated into four basic procedures: (1) Data Copying Procedure, copying the raw data from initial tape to disk pack for later processing; (2) Data Converting Procedure, converting the raw data of each channel currently in service into the appropriate process variables by using calibration curves; (3) Data Storage, preserving raw and converted data for later use and for historical purposes; and (4) Recovery of Data, recovering selected data for use in analysis and evaluation. This Data Processing System built up a data base to supply data for simulation and analysis of any operating day since the ADVS began operations and data collection on January 23, 1980.Item Development and use of a duststorm simulation chamber to evaluate solar concentrator degradation as characterized by loss in reflectivity(Texas Tech University, 1980-12) Collier, Elwin GreggNot availableItem Dynamic Reactive Power Control of Isolated Power Systems(2012-10-03) Falahi, MiladThis dissertation presents dynamic reactive power control of isolated power systems. Isolated systems include MicroGrids in islanded mode, shipboard power systems operating offshore, or any other power system operating in islanded mode intentionally or due to a fault. Isolated power systems experience fast transients due to lack of an infinite bus capable of dictating the voltage and frequency reference. This dissertation only focuses on reactive control of islanded MicroGrids and AC/DC shipboard power systems. The problem is tackled using a Model Predictive Control (MPC) method, which uses a simplified model of the system to predict the voltage behavior of the system in future. The MPC method minimizes the voltage deviation of the predicted bus voltage; therefore, it is inherently robust and stable. In other words, this method can easily predict the behavior of the system and take necessary control actions to avoid instability. Further, this method is capable of reaching a smooth voltage profile and rejecting possible disturbances in the system. The studied MicroGrids in this dissertation integrate intermittent distributed energy resources such as wind and solar generators. These non-dispatchable sources add to the uncertainty of the system and make voltage and reactive control more challenging. The model predictive controller uses the capability of these sources and coordinates them dynamically to achieve the voltage goals of the controller. The MPC controller is implemented online in a closed control loop, which means it is self-correcting with the feedback it receives from the system.Item Economic analysis of wind and solar energy sources of Turkey(2011-05) Erturk, Mehmet; Groat, Charles G.; Jablonowski, Christopher J.Renewable energy sources have become very popular in the last years in electricity generation thanks to the technological developments, the increase in the price of fossil fuels and the environmental concerns. These factors have also prompted Turkey to utilize her very rich renewable energy sources to meet the demand increasing around 7% annually. In this study, solar and wind energy potential of Turkey is analyzed in terms of its economics to find out whether these sources are real alternatives to fossil fuels in electricity generation. Before this analysis, wind and solar energy technologies and costs and wind and solar energy potential of Turkey are discussed. Then, models are set up for five technologies which are onshore wind, offshore wind, solar PV, solar trough and solar tower technologies models to calculate cash flows which are used to calculate payback, NPV, IRR, LCE and shut-down price to conduct economic analysis. In addition to base case scenario, uncertainty analysis is done for the most promising technologies which are onshore wind and solar tower technologies by evaluating NPV and LCE under uncertain environment. The main finding of these analyses is that only onshore wind projects are attractive in Turkey; none of other technologies is attractive. However, with a minor increase in the regulated price for solar thermal electricity, tower plant projects will also be attractive.Item Feasibility study of an integrated wind and solar farm by evaluating the wind turbine shadows(2012-05) Shanghavi, Sahil; Grady, W. M.; Santoso, SuryaThis thesis analyzes the feasibility of having an integrated wind and solar farm to optimize the use of land resources and capital investment by evaluating the effect that wind turbine shadows have on the area surrounding them. Two methods are used to predict shadow impact. The first method is based on the traditional textbook “Clear Sky” equations, which have maximum sensitivity to shadows because the method considers every day to be a perfect day. The second method uses measured global-horizontal and diffuse-horizontal solar radiation in units of W/m2, which take into account the true variations of daily conditions. The calculations are performed for 1 square meter surfaces, over different assumed areas of a wind power plant, for every second of the day. For purposes of shadow calculations, the tip-top height (i.e., tower height plus blade length) is used. All calculations are performed with the specifications of a GE 1.5 MW wind turbine, which is the most commonly used wind turbine in USA.Item Firming Wind Energy with Solar Photovoltaics(2011-08) Pattison, Chris; Swift, Andrew H. P.; Gilliam, Kathleen; Giesselmann, Michael G.; Silva, Dakshina G. d.A number of research and development groups and several renewable project operators have examined combining wind power production with on-site solar power production. Past research has been devoted to small, off-grid applications only. In the absence of actually building a utility-scale project, short time scale (5 minutes) estimates of combined power production are difficult to simulate due to the lack of hub-height wind data combined with on-site solar insolation data available in similar time scales. This presentation will present hub-height, high-fidelity, wind data from the Texas Tech University’s 200-meter meteorological tower combined with a co-located solar pyranometer to estimate short-term (5-minute) power production data. Recent reduced costs associated with solar-PV may make this option more attractive in the future. This analysis addresses fixed-plate, single- and dual-axis PV arrays. This presentation also includes an economic analysis of the wind-only, solar-only, and combined wind-solar plants. Over the past few years, renewable energy has entered the electrical grid at an exponential rate. To reduce the uncertainties for the grid operator, wind power plants “firm” their production under power purchase agreements (PPA’s) paying penalties when the “firm” production is not met. This puts more risk on the wind power provider in order to secure a higher sale price. Since wind power is best at night and solar power is only during the day, by combining their synergies, uncertainty is reduced and higher PPA’s are possible. This analysis will present economic estimates of the ability of plant operators to secure higher purchase prices for power by raising the “firm” production level and reducing the uncertainties.Item An integrated energy storage scheme for a dispatchable wind and solar powered energy system(2009-12) Garrison, Jared Brett; Webber, Michael E., 1971-; Schmidt, PhilipWind and solar technologies have experienced rapid market growth recently as a result of the growing interest for implementation of renewable energy. However, the intermittency of wind and solar power is a major obstacle to their broader use. The additional risks of unexpected interruptions and mismatch with demand have hindered the expansion of these two primary renewable resources. The goal of this research is to analyze an integrated energy system that includes a novel configuration of wind and solar coupled with two storage methods to make both wind and solar sources dispatchable during peak demand, thereby enabling their broader use. Named DSWiSS for Dispatchable Solar Wind Storage System, the proposed system utilizes compressed air energy storage (CAES) that is driven from wind energy and thermal storage supplied by concentrating solar thermal power in order to achieve this desired dispatchability. Although DSWiSS mimics the operation of a typical CAES facility, the replacement of energy derived from fossil fuels with energy generated from renewable resources makes this system unique. While current CAES facilities use off peak electricity to power their compressors, this system uses power from wind turbines. Also, rather than using natural gas for heating of the compressed air before its expansion through a turbine, DSWiSS uses solar thermal energy and thermal storage. For this research, two models were created; the first is a dynamic model of a 1.5 MW variable speed wind turbine, programmed in PSCAD/EMTDC, that utilizes rotor resistive control to maintain rated power output. This model simulates the dynamic response of the wind turbine to changing wind conditions as well as the nominal performance parameters at all wind speeds. The second model is a steady state thermodynamic simulation of the turbomachinery power unit in the DSWiSS facility. By assuming conditions similar to those of a currently operating CAES facility in McIntosh, Alabama, the model calculates the performance parameters of DSWiSS and estimates the relative energy input requirements. By combining these models with a levelized lifetime cost analysis estimates of the power system performance and the cost of energy for the DSWiSS facility were estimated. The combination of these components yielded an efficiency greater than 46% for the main power block and a nearly equal utilization of both renewable resources. It was also estimated that the overall system is only slightly more expensive per unit of electricity generated than the current technologies employed today, namely coal, nuclear, and natural gas, but is comparable to a stand-alone solar thermal facility. However, this economic analysis, though accurate with regard to the technologies chosen, will not be complete until cost values can be placed on some of the externalities associated with power generation such as fuel cost volatility, national security, and emissions.Item Integration and Optimization of Trigeneration Systems with Solar Energy, Biofuels, Process Heat and Fossil Fuels(2012-02-14) Tora, EmanThe escalating energy prices and the increasing environmental impact posed by the industrial usage of energy have spurred industry to adopt various approaches to conserving energy and mitigating negative environmental impact. This work aims at developing a systematic approach to integrate solar energy into industrial processes to drive thermal energy transfer systems producing power, cool, and heat. Solar energy is needed to be integrated with other different energy sources (biofuels, fossil fuels, process waste heat) to guarantee providing a stable energy supply, as industrial process energy sources must be a stable and reliable system. The thermal energy transform systems (turbines, refrigerators, heat exchangers) must be selected and designed carefully to provide the energy demand at the different forms (heat, cool, power). This dissertation introduces optimization-based approaches to address the following problems: ? Design of cogeneration systems with solar and fossil systems ? Design and integration of solar-biofuel-fossil cogeneration systems ? Design of solar-assisted absorption refrigeration systems and integration with the processing facility ? Development of thermally-coupled dual absorption refrigeration systems, and ? Design of solar-assisted trigeneration systems Several optimization formulations are introduced to provide methodical and systematic techniques to solve the aforementioned problems. The approach is also sequenced into interacting steps. First, heat integration is carried out to minimize industrial heating and cooling utilities. Different forms of external-energy sources (e.g., solar, biofuel, fossil fuel) are screened and selected. To optimize the cost and to overcome the dynamic fluctuation of the solar energy and biofuel production systems, fossil fuel is used to supplement the renewable forms of energy. An optimization approach is adopted to determine the optimal mix of energy forms (fossil, bio fuels, and solar) to be supplied to the process, the system specifications, and the scheduling of the system operation. Several case studies are solved to demonstrate the effectiveness and applicability of the devised procedure. The results show that solar trigeneration systems have higher overall performance than the solar thermal power plants. Integrating the absorption refrigerators improves the energy usage and it provides the process by its cooling demand. Thermal coupling of the dual absorption refrigerators increases the coefficient of performance up to 33 percent. Moreover, the process is provided by two cooling levels.Item Mixed metal oxide semiconductors and electrocatalyst materials for solar energy conversion(2013-12) Berglund, Sean Patrick; Mullins, C. B.The sun is a vast source of renewable energy, which can potentially be used to satisfy the world's increasing energy demand. Yet many material challenges need to be overcome before solar energy conversion can be implemented on a larger scale. This dissertation focuses on materials used for solar energy conversion through photo-electrochemical (PEC) processes. It discusses methods for improving PEC materials, namely mixed metal oxide semiconductors, by nanostructuring, incorporation of additional elements, and application surface electrocatalysts. In this dissertation several material synthesis techniques are detailed. A high vacuum synthesis process known as reactive ballistic deposition (RBD) is used to synthesize nanostructured bismuth vanadate (BiVO₄), which is studied for PEC water oxidation. Additionally, ballistic deposition (BD) is used to incorporate Mo and W into nanostructured BiVO₄ to improve the PEC activity. An array dispenser and scanner system is used to incorporate metals into copper oxide (CuO) and copper bismuth oxide (CuBi₂O₄) and over 3,000 unique material compositions are tested for cathodic photoactivity. The system is also used to test 35 elements as single component metal oxides, mixed metal oxides, and dopants for titanium dioxide (TiO₂) for use in dye-sensitized solar cells (DSCs). Lastly, RBD is used to deposit tungsten semicarbide (W₂C) onto p-type silicon (p-type) substrates as an electrocatalyst for PEC proton reduction. In many cases, the synthesis techniques and new material combinations presented in this dissertation result in improved PEC performance. The materials are thoroughly assessed and characterized to gain insights into their nanostructure, chemical composition, light absorption, charge transport properties, catalytic activity, and stability.Item Nanotechnology for Solar-hydrogen Production via Photoelectrochemical Water-splitting: Design, Synthesis, Characterization, and Application of Nanomaterials and Quantum Dots(2012-02-14) Alenzi, Naser D.Hydrogen production by water-splitting using solar energy and nanostructure photocatalysts is very promising as a renewable, efficient, environmentally clean technology. The key is to reduce the cost of hydrogen production as well as increase the solar-to-hydrogen conversion efficiency by searching for cost-effective photocatalytic materials. In this dissertation, energy efficiency calculation was carried out based on hydrogen production observation to evaluate the nanomaterials activity. The results are important to gain better understanding of water-splitting reaction mechanism. Design, synthesis, characterization/properties and application of these nanomaterials was the road-map to achieve the research objectives. The design of TiO2 is selected based on unique photocatalytic and photovoltaic properties and high stability in aqueous solution. Various structures of nanocomposites TiO2 were designed according to their characteristics and potential activity. TiO2 with quantum dots, nanocomposites thin film, nanofibers, nanorods, nanowires (core/shell), nanotubes, nanopowders, nanoparticles, and nanosphere decorated with low cost metals, sensitized with dye, and doped with nitrogen are designed. Green physical and chemical synthesis methods such as sol-gel techniques, autoclave, microwave, electrospinning, wet impregnation, hydrothermal, chemical vapor deposition, template-based fabrication (porous anodic aluminium oxide membrane), drop casting, dip coating, wet coating were used to synthesize and fabricate the nanomaterials and quantum dots.Both bottom-up and top-down synthesis techniques were used. The ability to control and manipulate the size, shape/geometry, crystal structure, chemical compositions, interaction and interface properties of these materials at nano-scale during the synthesis enable to enhance their thermal, optical, chemical, electrical, ?etc properties. Several characterization techniques such as XRD, XPS, EDS, SEM, UV-visible spectra, and optical microscopic and digital camera were also obtained to characterize the properties and confirm to achieve the desired design. The application or processing to test the activity of these nanomaterials for hydrogen production by water-splitting was conducted through extensive experimental program. It was carried out in a one photo-single column experimental set-up to detect hydrogen evolution. A high throughput screening process to evaluate single photo reduction catalysts was established here for simplicity, safety, cost-effective and flexibility of testing nanomaterials for water photoreduction reactivity and hydrogen generation. Therefore, methanol as electron donor or oxidation agent was mixed with water in equal volume ratio in order to prevent the oxygen evolution and only measured the time course of hydrogen production. The primary objectives of this study is to investigate the following (1) The structure-properties relationship through testing quantum dots, nanocomposites thin film, nanofibers, nanorods, nanowires (core/shell), nanotubes, nanopowders, nanoparticles, nanospheres of TiO2 decorated with metals, dye sensitization, and nitrogen-doping. (2) The role of adding electron donors/relays to solution and their effect on semiconductor surface-electrolyte interface under constant conditions such as KI, Mv 2, NaCl, NaHCO3, sea and pure water. (3) Band gap and defect engineering by cation and anion doping. (4) Quantum dots and dye sensitization effect. The nanomaterials activity evaluated based on observed hydrogen production rate (?mol/h/g) experimentally and based on the energy efficiency (percent) calculation. Major findings in this dissertation are (1) A high throughput screening process to evaluate single photoreduction catalysts for solar-hydrogen production by water-splitting was established. (2) nanofibers structure of TiO2 doped with nitrogen, sensitized with dye (Rose Bengal Sodium) and quantum dots (CuInS2), and decorated with metals (Ag) showed the high solar-to-hydrogen conversion efficiency and high hydrogen production rate (3) Simple, safe, inexpensive, robust, efficient and green physical and chemical synthesis methods were used to prepare the nanomaterials and quantum dots. (4) Gaining insight and better understanding of water-splitting reaction mechanism by (a) Studying the structure-properties relationship of nanomaterials (b) Studying the role of additives on surface-interface chemistry of semiconductor and electrolyte (c) Knowing how to reduce the electron-hole recombination reactions to enhance quantum efficiency (d) Extending the absorption of nanomaterials to harness the visible light of solar spectrum radiation by doping and defect chemistry.Item Optical analysis of spherical segment solar collectors(Texas Tech University, 1977-05) Brock, Billy C.A powerful new approach for the calculation of optical flux distributions and power concentration ratios is described. This theory can be applied to mirrors of any shape, illuminated by a source of arbitrary angular extent provided appropriate structure relations can be determined. The method is not restricted to single reflections, but is valid for light which reflects from the mirror any number of times. The work focuses on spherical mirror segments with conical receivers. The result is an extremely accurate expression for the optical power concentration. The method is also applicable for point source illumination.Item Optical power concentrations on aligned and misaligned receivers in solar gridiron power systems(Texas Tech University, 1978-08) Leung, HipsumA powerful strategy, the ROSA approach, has been developed for calculation of optical power concentrations produced by solar collectors. The ROSA method is yery general and can be applied to concentrators and receivers of any geometrical shape. In addition, the method can be used for light from a source of finite extent undergoing any number of multiple reflections on the collector mirror. The work presented here is applied to optical concentrations on a conical receiver suspended in a spherical segment collector as appropriate for a Solar Gridiron Power System. Optical power concentrations on both aligned and misaligned receivers are described for various solar inclinations. A simplified approach for calculating azimuthally averaged power concentrations on a perfectly aligned receiver is also presented.Item Optimal design and integration of solar systems and fossil fuels for process cogeneration(2009-05-15) Tora, Eman Abdel-Hakim Aly MohamedBecause of the fluctuations in incident solar power, outlet power also changes over time (e.g., on an hourly basis or seasonally). If there is a need for a stable power outlet, there are options towards a steady state output of the system. This work is aimed at the development of systematic design procedures for two solar-based power generation strategies. The first is integration of fossil-fuel with the solar system to provide a compensation effect (power backup to supplement the power main source from solar energy). The second is the use of thermal energy storage (TES) systems to save solar energy in a thermal form and use it when solar input decreases. A common TES configuration is the two-tank system which allows the use of the collector heat transfer fluid (HTF) as a storing medium. For the two tanks, one tank has the hot medium (e.g., a molten salt) and the second has the cold storage media. Specifically, the following design challenges are addressed: 1. What is the optimal mix of energy forms to be supplied to the process? 2. What are the optimal scenario and integration mode to deliver the selected energy forms? How should they be integrated among themselves and with the process? 3. What is the optimal design of the energy systems? 4. What is the optimal dynamic strategy for operating the various energy systems? 5. What is the feasibility of using thermal energy storage to this optimum fossil fuel system? The developed procedure includes gathering and generation of relevant solar and climatic data, modeling of the various components of the solar, fossil, and power generation systems, and optimization of several aspects of the hybrid system. A case study is solved to demonstrate the effectiveness and applicability of the devised procedure.Item Performance analysis of a solar gridiron design verification system(Texas Tech University, 1981-05) Watson, Karan LeaNot availableItem The potential for biomimetic solar energy(2014-05) McGinnis, Colleen Jean; Moore, Steven A., 1945-The purpose of this thesis is to explore the potential for integrating biomimetic thinking into the design and implementation of photovoltaic energy systems in a way that promotes ecological health, economic feasibility, and equal access to cleaner energy. Photovoltaic energy production is among the most promising renewable energy sources, however, current conventional photovoltaic systems exhibit a number of shortcomings. Steering innovation toward socio-technical systems that are integrated with ecological systems will help support human needs without inhibiting larger ecological function. This investigation began with the construction of a conceptual biomimetic lens from a foundation of literature related to biomimicry in the built environment. Next, the underlying elements, interconnections and functions of both the ecological systems involved in photosynthesis and socio-technical systems related to photovoltaic energy production were defined and examined. The biomimetic lens was then applied to each system to envision biomimetic approaches to address shortcomings of current conventional photovoltaic systems. The suggested approaches aim to address shortcomings in the design, manufacture, and implementation of photovoltaic systems in ways that mimic key principles found in biology and ecology. Since the success of ecological systems is embedded in the nesting of interrelated systems, the biomimetic lens was applied at multiple scales: the chloroplast/solar cell, the leaf/solar panel, the plant/solar array, and the ecosystem/community scale. The results of this study both suggest the direction of further research in the development of biomimetic solar energy systems and provide insight into the effectiveness of biomimetic thinking as a strategy for designing equitable, economical, and ecologically sound systems.Item