Optimization Study of a Combined Wind-Solar Farm for a Specified Demand

At the present time, using wind and solar energy for producing electricity in the United States is becoming cost competitive. According to Lazard’s 2019 [36] levelized cost of energy (LCOE) analysis of a number of energy sources used for producing electricity in the United States, wind and solar are cheaper than natural gas and coal. While capital, maintenance, operation, and fuel costs are included in LCOE numbers, energy source intermittency is not. Intermittency is an important issue with wind and solar energy sources, but not with natural gas or coal energy sources. Combining wind and solar energy sources into one electrical generating station, is one means by which the intermittency of the electricity provided by wind alone and solar alone can be reduced. The combination of wind turbines and solar photovoltaic panels into a wind-solar farm can produce electricity over a greater fraction of the day or year than wind or solar alone. Predicting the energy output of different combinations of wind turbines and solar panels in a wind-solar farm is an objective of this work. While yearly electricity production rates are an important and necessary part of this work, this quantity does not provide a means to compare the wind-solar farms to each other, to a pure wind farm, to a pure solar farm, or to meeting a given electrical demand by purchasing all electricity from the local electrical grid. An economic analysis has to be performed to do this. This is the ultimate objective of this work. The economic analysis done in this work determines the net present cost of providing a specified electricity demand by a wind-solar farm with grid backup. Including grid purchased electricity to meet demand that cannot be met by the wind-solar farm is essential in this economic analysis. This sets the net present cost of providing all the electricity demand by grid purchased electricity as the cost that must be beat by a wind-solar farm with grid backup. Using grid backup also ensures that all of the electrical demand is met. Doing the economic analysis this way, means the intermittency costs of wind and solar are included in the economic analysis. The electrical output of many combinations of wind turbines and solar panels into one wind-solar farm are simulated in this work to see which combination provides the lowest netiv present cost of electricity for a specified electrical demand. The net present cost analysis performed n this work is different than a LCOE analysis because all the electricity produced for the net present cost analysis does not have value. For most of the simulations in this work, excess generated electricity is given no value. Only one economic simulation, for a given location, performed in this work is allowed to sell excess electricity from the wind-solar farm back to the electrical grid; and this is done at half the price at which it is purchased. The mathematical models that were pieced together to perform this work are presented. Detailed models of the solar and wind resource are utilized. The conversion of solar energy into electricity by the solar panels is handled with a solar panel efficiency. The conversion of wind energy into electricity is handled with a wind turbine power curve. Demand profiles for a given location are obtained from those published on the internet. The net present cost analysis is done including the time value of money. A MATLAB program was written to obtain numerical results from the mathematical models brought together to simulate the performance and costs of a windsolar farm with gird backup. Many results are presented in this thesis for three different cities in the United States. These cities are Rio Vista, California, Dallas, Texas, and Dayton, Ohio. For each of these locations, electricity demand profiles, wind and solar resource profiles, electricity produced by different sizes of wind-solar farms, excess electricity produced by these wind-solar farms over the required demand, and the net present cost of these wind-solar farms with grid backup using different cost constraints are presented. A base case of costs is developed and then single changes to these base case costs are investigated. The results show that combining wind turbines with photovoltaic panels can reduce the cost of providing a specified electricity demand. In Rio Vista, California wind-solar farms are cost competitive, whereas in Dayton, Ohio they are not. Whether a windsolar farm is cost competitive in Dallas, Texas depends on the cost conditions. A key factor in determining the attractiveness of wind-solar farms under the conditions used in this study, is the cost of grid electricit

A Model for Thermal Growth of Ultrathin Silicon Dioxide in O2 Ambient: A Rate Equation Approach

A new thermal oxidation model based on a rate equation approach with concentration dependent diffusion coefficient is proposed for ultrathin SiO2 for thicknesses of the order of 100 Å. The oxidation reaction of silicon is assumed to be dependent on the concentrations of unreacted silicon and oxygen. The results of oxide thickness versus oxidation time for various growth conditions and activation energies for diffusion coefficients are in agreement with various experimental data for O2 ambient

Photonics in engineering

This inaugural event is dedicated to showcasing the renewable/sustainable energy projects of UNLV faculty, staff, students, and collaborators, as well as other external projects underway statewide and nationally. The development and utilization of new technologies to protect the environment, achieve energy independence, and strengthen the economy will be explored. Speakers and poster-session presenters will provide further insight to many ongoing projects and innovative research ideas. Organized by UNLV’s Office of Strategic Energy Programs, the event offers participants the opportunity to learn about energy projects and will encourage networking and collaboration. This symposium is intended for researchers, educators, students, policy makers, public and private-sector energy and environmental professionals, and citizens

Analytical Expressions for Tunneling Time through Single and Double Barrier Structures

In the past, the quantum mechanical tunneling time through simple rectangular barrier has been obtained by various theoretical approaches including the dwell time, the phase delay time, the Larmor clock time and also using the numerical analysis of wave packets. The agreement among these approaches over a range of incident electron energy is far from satisfactory. In this manuscript, analytical expressions for the tunneling time are derived based on the group velocity approach (referred hereafter as the average particle time, τAPT) for single and double rectangular potential barriers under zero bias. The results of the single barrier case, including the limiting value of the tunneling time for various energy limits, are compared with these previous tunneling time calculations. The τAPT results provide physically meaningful tunneling times for zero and infinite incident energy limits of the electron. The τAPT for the double barrier structure is computed from the analytical solution as a function of the incident energy of the electron for two experimentally studied resonant tunneling structures. For both the single and double barrier cases, the effect of the structure parameters such as barrier width, height, and well width on the τAPT are obtained and reported

Model for Alumina nanopore-based Optical Filter

Alumina nanopore structures find applications in magnetic sensors, optical filters, and various biological devices. In this work, we present a ray-optics model for the optical filter. We present a detailed simulation and a simplified analytical expression for the reflectance as a function of the alumina parameters such as pore diameter, pore density, alumina thickness, and a function of the wavelength and angle of incidence of the illuminating plane electromagnetic wave. The reflectance vs wavelength in the range of 400–800nm obtained from the simulation and the analytical expression are compared with that of the experiments for thin and thick alumina. All results agree well for a thin layer of alumina pores (90nm) . When comparing experimental and theoretical results for a thick layer of alumina (1300nm) , the results disagree. One possible explanation for the discrepancy is that the dielectric constant may vary with the thickness of the anodized alumina. Based on this work, a ray optic mixing theory is presented for waves propagating obliquely to parallel slabs of dielectric mediums with a degree of spatial periodicity

Low-temperature Molecular Beam Epitaxy of GaAs: A Theoretical Investigation of Antisite Incorporation and Reflection High-energy Diffraction Oscillations

Surface dynamics dominate the incorporation of charged, As+Ga, and neutral, As0Ga, antisite arsenic, and the temporal variation of reflection high-energy electron diffraction(RHEED) intensity in the low-temperature molecular beam epitaxy of (100) gallium arsenide(GaAs). A rate equation model is proposed which includes the presence and dynamics of a physisorbed arsenic (PA) layer riding the growth surface. The PA layer dictates the incorporation and concentration of As+Ga and As0Ga. Additionally, it influences the RHEED oscillations (ROs) behavior and the RO’s dependence on its coverage through its contribution to the reflected intensity. The model results for the dependence of As+Ga and As0Ga concentrations on beam equivalent pressure (BEP) and growth temperature are in good agreement with experimental data. The experimental observations can be explained based on the saturation of the PA coverage at one monolayer and the competing rate processes such as the AsGa incorporation into and evaporation from the crystalline surface. Using the same kinetic model for the temporal behavior of the surface, the contribution of the PA layer to the RHEED intensity is computed based on kinematical theory of electron diffraction. The experimental observation of the ROs during growth at high and low temperatures with no ROs in the intermediate temperature range of 300–450 °C is in good agreement with our model results. At low temperatures, the surface is covered by the PA layer whose step density depends on that of the subsurface crystalline GaAs. Thus, a temporal variation of the step density of subsurface crystalline GaAs results in ROs, but with a different step height, that of the PA layer, of 2.48 Å. At high temperatures, the crystalline GaAs is exposed to the RHEED beam due to the evaporation of the PA layer and the ROs appear due to periodic step-density oscillations with a step height of 1.41 Å, which is the Ga–As crystalline interplanar distance. At intermediate temperatures, the surface is partially covered by the PA layer resulting in RHEED reflection contributions from both surfaces covered by the PA layer and crystal. Due to the very different interplanar distances between the crystalline GaAs and the PA layers, complete destructive interference of the RHEED intensity results at a 0.5 surface coverage of the PA layer. The RO dependence on the As BEP is also presented and discussed

Novel Theorems and Algorithms Relating to the Collatz Conjecture

Proposed in 1937, the Collatz conjecture has remained in the spotlight for mathematicians and computer scientists alike due to its simple proposal, yet intractable proof. In this paper, we propose several novel theorems, corollaries, and algorithms that explore relationships and properties between the natural numbers, their peak values, and the conjecture. These contributions primarily analyze the number of Collatz iterations it takes for a given integer to reach 1 or a number less than itself, or the relationship between a starting number and its peak value.Comment: 17 pages, 4 figures, 4 tables, 3 algorithms, 10 theorems, 2 corollaries, GitHub cod

Thin-film fabrication for high pressure thermoelectric and electrical resistivity studies

Thermoelectric materials are of interest for application such as thermoelectric cooler in microprocessors and power generators in cars. High pressure plays an important role in understanding the changes in the figure of merit of thermoelectric thin films. To study the thermoelectric thin films a direct approach is to fabricate the thin film on the surface of a diamond anvil, so that the pressure dependence of structure and transport properties can be investigated easily. If we could successfully fabricate the electrical probes by depositing thin films, then it reduces the use of electrical wires as probes inside the diamond cell, as the wires are easily breakable at high pressure. We have study different Molybdenum (MO) electrode fabrication and methods to deposit thermoelectric thin films using sputtering deposition (physical vapor deposition)

Energy Efficient RGBW Pixel Configuration for Light-emitting Displays

A study on LED displays has been conducted exploring a more efficient method for color generation than the traditional method. The study is comprehensive and thoroughly performed employing various sets of experiments in order to examine the functionality of the new proposed scheme which includes a literature review, theoretical modeling based on a scientific study, experimental data measurements of a developed prototype, and statistical data based on a survey. This study resulted in very interesting outcomes that may lead to a tremendous change in the existing LED display technology

On the Solutions of Three Variable Frobenius Related Problems Using Order Reduction Approach

This paper presents a new approach to determine the number of solutions of three variable Frobenius related problems and to find their solutions by using order reducing methods. Here, the order of a Frobenius related problem means the number of variables appearing in the problem. We present two types of order reduction methods that can be applied to the problem of finding all nonnegative solutions of three variable Frobenius related problems. The first method is used to reduce the equation of order three from a three variable Frobenius related problem to be a system of equations with two fixed variables. The second method reduces the equation of order three into three equations of order two, for which an algorithm is designed with an interesting open problem on solutions left as a conjecture