Browsing by Subject "Wind"
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Item A reverse osmosis treatment process for produced water: optimization, process control, and renewable energy application(2009-06-02) Mareth, BrettFresh water resources in many of the world's oil producing regions, such as western Texas, are scarce, while produced water from oil wells is plentiful, though unfit for most applications due to high salinity and other contamination. Disposing of this water is a great expense to oil producers. This research seeks to advance a technology developed to treat produced water by reverse osmosis and other means to render it suitable for agricultural or industrial use, while simultaneously reducing disposal costs. Pilot testing of the process thus far has demonstrated the technology's capability to produce good-quality water, but process optimization and control were yet to be fully addressed and are focuses of this work. Also, the use of renewable resources (wind and solar) are analyzed as potential power sources for the process, and an overview of reverse osmosis membrane fouling is presented. A computer model of the process was created using a dynamic simulator, Aspen Dynamics, to determine energy consumption of various process design alternatives, and to test control strategies. By preserving the mechanical energy of the concentrate stream of the reverse osmosis membrane, process energy requirements can be reduced several fold from that of the current configuration. Process control schemes utilizing basic feedback control methods with proportional-integral (PI) controllers are proposed, with the feasibility of the strategy for the most complex process design verified by successful dynamic simulation. A macro-driven spreadsheet was created to allow for quick and easy cost comparisons of renewable energy sources in a variety of locations. Using this tool, wind and solar costs were compared for cities in regions throughout Texas. The renewable energy resource showing the greatest potential was wind power, with the analysis showing that in windy regions such as the Texas Panhandle, wind-generated power costs are approximately equal to those generated with diesel fuel.Item Aeolian dune-field boundary conditions and dune interactions related to dune-field pattern formation on Earth and Mars(2009-12) Ewing, Ryan Cotter; Kocurek, GaryAeolian dune fields form some of the most striking patterns on Earth and Mars. These patterns reflect the internal dune dynamics of self-organization within boundary conditions, which are the unique set of environmental variables within which each dune field evolves. Dune-field pattern self-organization occurs because of interactions between the dunes themselves and the rich diversity of dune-field patterns arises because boundary conditions alter the type and frequency of dune interactions. These hypotheses are explored in three parts. First, source-area geometry and areal limits are two newly recognized boundary conditions. Measurements of crest length and spacing from satellite images of dune patterns with point and line source-area geometries show an increase in crest length and spacing over distance, whereas crest length and spacing in plane-sourced patterns emerge equally across the dune field. The areal limit boundary condition is the size and shape of the dune field itself. Empirical measurements from ten dune fields ranging over four orders of magnitude in area show that spacing increases and defect density decreases as the area of the dune field increases. A simple analytical model indicates that dune fields that are five times longer in the dune migration direction can achieve the greatest spacing for a given area. Second, time-series aerial photographs and airborne LiDAR show that fully developed, crescentic aeolian dunes at White Sands, New Mexico, interact and the dune pattern organizes in systematically similar ways as wind ripples and subaqueous dunes and ripples. Interaction type, classified as constructive, regenerative or neutral in terms of pattern development, changes spatially with the pattern because of the imposition of the line-source area and sediment availability boundary conditions. Upwind dominance by constructive interactions at the field line-source yields to neutral and regenerative interactions in the sediment availability-limited field center. Third, the dune-field pattern in the Olympia Undae Dune Field on Mars is comprised of two generations of dunes. This scenario of pattern reformation with a new wind regime shows that the emergence of the younger pattern is controlled by the boundary condition of the antecedent dune topography imposed upon the interaction between the younger and older patterns.Item Characterization of hurricane gust factors using observed and analytical data(Texas Tech University, 2009-05) Edwards, Rebecca Paulsen; Schroeder, John L.; Gilliam, Kathleen; Smith, Douglas A.The nature of turbulence in the hurricane boundary layer has been the subject of much discussion. Two questions in particular continue to be the source for debate and ongoing research. The first question is whether or not hurricane GFs exhibit the same behavior as GFs from winds generated by extratropical systems (thunderstorms excluded). The second question is whether the structure of the wind, and the resulting gust factors, change at high wind speeds. This study seeks to address those two questions using a variety of data sources and analysis techniques. Observational data were collected from both landfalling tropical cyclones and synoptically generated extratropical wind. Analytical data at a variety of wind speeds were created using an inverse fast Fourier Transform of the universal spectrum for wind in the perturbed terrain. Gust factors and other parameters were computed for both types of data and the results assimilated in a data base. Analysis of these data yielded interesting results. A strong dependence on surface roughness was noted for gust factors from both observed and analytical data. However, once efforts were made to control for this dependency by stratifying the data into roughness regimes using the roughness length, slight differences between the tropical and extratropical gust factor data remained. Analysis of the artificial data, suggest spectral differences between the tropical and extratropical regimes due to the presence of additional low-frequency energy in the tropical regime. A slight decrease of the gust factor with increasing wind speed was noted in the high-speed analytical data. A similar decrease was suggested in the tropical data. It was concluded that the low-frequency spectral differences between the two regimes have less of an effect on the resulting gust factors as the wind speed increases, resulting in better agreement between the two distributions.Item Concerto for piano and wind ensemble(2012-05) Stanton, Zachary Kane, 1983-; Pinkston, Russell; Welcher, Dan; Grantham, Donald; Sharlat, Yevgeniy; O'Hare, ThomasConcerto for Piano and Wind Ensemble is a 16-minute work for piano and winds, brass, and percussion. Although piano is my primary instrument, I have written relatively little for it. With this piece I sought to write a work in the vein of the Romantic and early Twentieth Century piano concerto repertoire, which I listened to and absorbed as a young musician, but with a more contemporary harmonic language. Rather than using the traditional orchestra as the accompanying ensemble, I chose the wind ensemble, which has a limited concerto repertoire, giving me the opportunity to make a meaningful contribution to its literature.Item Design and control of an integrated wind-water desalination system for an inland municipality(Texas Tech University, 2008-08) Noll, Dennis D.; Ewing, Bradley T.; Song, Lianfa; Swift, Andrew H. P.; Chapman, Jamie C.Current water pricing standards do not take economic responsibility for dwindling potable water aquifer resources. By only incorporating financial, but not true economic costs of these scarce resources, serious depletion of these often slow-recharging groundwater resources has occurred in many areas in the United States. Aquifer depletion for some areas looms on a 50-year or closer horizon, and many municipalities in the Southwest and elsewhere face potential distress due to lack of sustainable fresh water availability. In order for these cities to remain economically and physically viable, alternative water resources must be found. An affected West Texas inland municipality will become the subject of research to evaluate the technology and economics of a full-scale, integrated, wind-powered reverse osmosis water purification system. The integrated system will be applied to produce potable water from a brackish aquifer using renewable energy to reduce the energy costs of the system. An adaptive and intelligent control algorithm will control the integrated wind-water system. The algorithm will process streaming real-time water use and electrical demand data in combination with wind speed measurements in order to determine the best use of the energy produced by a turbine array: either for water purification or for displacing conventional power on other municipal loads. The end product of this system is a water purification process that will utilize a brackish water aquifer for all of the city‘s potable water needs, and wind energy for all associated pumping, reverse osmosis, distribution and other electrical loads.Item Estimating emissions impacts to the bulk power system of increased electric vehicle and renewable energy usage(2013-12) Meehan, Colin Markey; Webber, Michael E., 1971-; Baldick, RossThe research presented in this thesis examines the use of electric vehicles and renewable energy to reduce emissions of CO₂, SO₂ and NO[subscript x], and within the state of Texas. The analysis examines the impact of increased renewable energy output and electric vehicle charging on the emissions of fossil fuel electric generators used to serve the bulk power system within Texas. The analysis then compares those impacts to alternative scenarios in which fossil fuel generation replaces some renewable energy generation, and Internal Combustion Engine (ICE) vehicles of varying efficiency are used instead of electric vehicles. This research uses temporally-resolved regression analysis combined with a unit commitment and dispatch model that incorporates several different scenarios for EV charging and fuel mixes to evaluate emissions outcomes based on a variety of conditions. Hourly historical generation and emission data for each fossil fuel generator, combined with hourly output data for non-fossil fuel units aggregated by fuel type (i.e. nuclear, wind, hydro-electric) within the Electric Reliability Council of Texas (ERCOT) footprint is regressed to assess the impact of wind generation output on fossil-fuel generation emissions. The regression analysis is used to assess potential increases in emissions resulting from the ramping of fossil-fuel Electric Generation Units (EGUs) to compensate for variability in wind generation output due to changing weather conditions. The unit commitment dispatch model is used to evaluate the impact of changes in customer demand due to increased usage and charging of electric vehicles on the ERCOT system and any resulting increase in emissions from generation used to meet this new demand. The model uses detailed cost, performance and emissions data for EGUs in the ERCOT footprint to simulate the impact of a variety of charging scenarios and fuel mixes on EGU dispatch patterns and any resulting change in system-wide emissions. The results of this model are combined with the results of the regression analysis to present a more complete analysis of the combined impacts of increase EV and renewable energy usage on the emissions of CO₂, SO₂ and NO[subscript x] within the ERCOT footprint. Based on these analyses the increases in renewable energy generation demonstrate clear benefits in terms of emission reductions when the impacts of increased emissions due to more frequent ramping of fossil-fuel units are taken into account. This analysis also finds that EV charging generally has emissions benefits across a range of charging patterns and bulk power system fuel mixes, although in certain circumstances EV charging might result in higher emissions than the use of ICE vehicles. This research finds when future ICE vehicles with reduced emissions are taken into account, approximately half of the modeled scenarios show net emissions benefits from EV charging, while half show net emissions costs when emissions impacts across pollutants are taken into account.Item Examination of the Coastal Transition Zone in Hurricane Frances (2004)(2011-05) Hirth, Brian D.; Schroeder, John L.; Weiss, Christopher C.; Smith, Douglas A.Understanding the structure of the coastal internal boundary layer (IBL) during the landfall of a tropical cyclone has important ramifications on operational forecasting, structural design, and post-storm damage assessment. Despite these important issues, it is unclear how the structure of the IBL evolves at the coastline on micro- and meso-scales during a landfalling hurricane. Knowledge of the vertical kinematic structure within tropical cyclones over water has improved greatly through aircraft reconnaissance missions and the advent of GPS dropsondes and the Stepped Frequency Microwave Radiometers. Unfortunately, reconnaissance and research aircraft are limited to over-water missions resulting in a poor understanding of vertical kinematic structure near the coastal interface where changes in IBL structure are expected due to changes in coastal geometry and surface roughness. Additionally, IBL structure may evolve due to the passage of convective precipitation and associated downdrafts. A unique observational dataset was collected from the coastal transition zone in the onshore flow region of Hurricane Frances (2004) over Cape Canaveral, FL. Single- and dual-Doppler radar data collected by the Shared Mobile Atmospheric Research and Teaching radars provide the ability to discern horizontal and vertical mean IBL structure over a complex coastal interface while assessing the influence of a variable underlying surface and the passage of transient convective wind gusts. Additional wind speed data were collected by a meso-network of surface towers operated by the Cape Canaveral Air Force Station and Kennedy Space Center along with a portable surface tower deployed by Texas Tech University. Radar and tower data analyses reveal that IBL mean structure over the Cape Canaveral remains quite consistent during the landfall of Hurricane Frances, though IBL growth is suppressed when compared to empirical growth models. Additionally, transient convective gusts commonly perturb the mean structure at the top of the IBL, though the higher momentum associated with these gusts is typically not able to descend to the surface within an established IBL.Item Investigation of Data Quality for Wind Tunnel Internal Balance Testing(2013-04-04) Hidore, John PrestonAchieving high quality, consistency, and testing efficiency in wind tunnel tests using internal balances is accomplished through the use of new testing methods, analysis of data output, and standardized documentation of test procedures at the Texas A&M Low Speed Wind Tunnel. The wind tunnel is capable of performing internal balance testing on models that experience less than 500 pounds of normal force. Testing has shown less than a 3% mean flow variation with the sting mount installed and a turbulence intensity of less than 0.25%. Documentation of procedures and check- lists for installation of internal balance testing equipment and test execution provide higher efficiency and consistency during a test. A step-by-step examination of the data analysis routines and associated uncertainty equations show uncertainty in the force and moment coefficients for the Mark XIII internal balance to be approximately ? 0.05 and ? 0.02, respectively. Quantifying the uncertainty of the primary output parameters and showing repeatability of the data within the defined uncertainty limits achieved higher quality results.Item My good puzzle pieces: The environmental effects of knowledge(2013-07) Hurt, Alisa M.; Farris, Don R.; Wallace, Mark C.; Crooks, Steven M.Everything is related to everything. We are all the result of a never ending thread of cause and effects. As we evolve and progress, the choices we make add up to define our path. As an individual this decision making can be the make or break of our personal future. As a specie our actions have an exponential impact on our surroundings, making our choices either long term sustainable or not. We can only make wise choices by knowing the effects that our past has had on the environment and making corrections to diminish negative impacts while exploring and developing new avenues that make our progress sustainable. Hence the important role that knowledge plays in our future and the difference between our story being one of survival or annihilation.Item On the spiral troughs of Mars(2013-08) Smith, Isaac Blaine; Holt, John W., Ph. D.The north and south polar layered deposits (NPLD and SPLD respectively) of Mars are 2 – 3 km thick and mostly ice, comprising nearly all of the known water reserves on Mars. They are commonly believed to hold a detailed record of recent (~10 – 100 Myr) climate within their layers. Dominating the surface of the NPLD, intriguing spiral depressions called troughs, exhibit a pinwheel appearance. In late 2006, the Shallow Radar (SHARAD) instrument began making observations. SHARAD can detect internal structure within the PLD, making observations that are impossible with instruments that only inspect the surface. SHARAD data reveals a unique stratigraphic record associated with trough formation and migration. The troughs did not exist during deposition of the first half of NPLD accumulation but initiated some 1000 m below the current surface and have migrated as much as 100 km northward. Three processes are responsible for this migration: wind transport, insolation induced sublimation, and atmospheric deposition. I synthesize work from ground penetrating radar, optical imagery, established analogs, and atmospheric modeling in order to derive a process model that describes trough formation and evolution, including migration. The NPLD spiral troughs belong to a larger classification of features called cyclic steps, which can exist in either erosional or depositional environments. On the SPLD, troughs and a variety of other features exist. While SPLD features are more complex than NPLD troughs, they exist due to the same three processes.Item Understanding the strengths and weaknesses of a new-generation numerical weather prediction model for application to short-term wind energy prediction(2012-12) Fowler, Padriac; Ancell, Brian A.; Schroeder, John L.; Swift, Andrew H. P.; McCaa, JimWind power is a growing economy and science. It has far reaching consequences in all aspects of society and if goals of energy sustainability and security are to be met, wind power will become crucial. Numerous studies, including the U.S. Department of Energy’s report “20% by 2030”, have already shown the incredible growth of wind power in the past 5 years. A compelling problem with this growth is that in spite of all the wind power currently online in the United States, according to the “20% by 2030” report, we have only utilized about 0.3% of the total available land based wind power, and are only 11% of the way to the 2030 goal of 300GW of installed wind. Wind power is entirely at the mercy of the wind, and in essence, the entire atmosphere. These are very dynamic systems and because of this, the energy distribution and market system of the United States are already feeling the strain of integrating wind as a significant resource. One of the main ways in which wind integration is achieved is by producing wind power forecasts. To date, several works have concluded that wind speed and wind power forecasting have economic benefits for wind farms and are necessary for the best integration into the electric grid. The work of this thesis is simulation conducted with the Weather Research and Forecasting model. The model is run as an ensemble of simulations varying each only by atmospheric boundary parameterizations schemes. Three case studies significant to wind power are assessed and discussed in terms of overall weather prediction, atmospheric boundary layer processes, and their significance to wind energy prediction.Item The unlikely success of green power in America’s reddest state, and its uncertain future(2012-05) Gerdau, Axel; Dahlby, Tracy; Alves, RosentalThis narrative chronicles the development of the utility scale wind industry in Texas from the perspective of the people who made it possible. It also looks ahead at the challenges facing the most mature green power sector in the United States.Item Wind forecast verification : a study in the accuracy of wind forecasts made by the Weather Channel and AccuWeather(2011-08) Scheele, Kyle Fred; Bickel, J. Eric; Hasenbein, JohnThe Weather Channel (TWC) and AccuWeather (AWX) are leading providers of weather information to the general public. The purpose of this Master’s Report is to examine the wind speed forecasts made by these two providers and determine their reliability and accuracy. The data used within this report was collected over a 12-month period at 51 locations across the state of Texas. The locations were grouped according to wind power class, which ranged from Class 1 to Class 4. The length of the forecast period was 9 days for TWC and 14 days for AWX. It was found that the values forecasted by TWC were generally not well calibrated, but were never far from being perfectly calibrated and always demonstrated positive skill. The sharpness of TWC’s forecasts decreased consistently with lead time, allowing them to maintain a skill score greater than the climatological average throughout the forecast period. TWC tended to over-forecast wind speed in short term forecasts, especially within the lower wind power class regions. AWX forecasts were found to have positive skill the first 6 days of the forecasting period before becoming near zero or negative. AWX’s forecasts maintained a fairly high sharpness throughout the forecast period, which helped contribute to increasingly un-calibrated forecast values and negative skill in longer term forecasts. The findings within this report should help provide a better understanding of the wind forecasts made by TWC and AWX, and determine the strengths and weaknesses of both companies.