Browsing by Subject "Energy"
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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 An Energy Analysis Of A Large, Multipurpose Educational Building In A Hot Climate(2012-02-14) Kamranzadeh, VahidehIn this project a steady-state building load for Constant Volume Terminal Reheat (CVTR), Dual Duct Constant Volume (DDCV) and Dual Duct Variable Air Volume (DDVAV) systems for the Zachry Engineering Building has been modeled. First, the thermal resistance values of the building structure have been calculated. After applying some assumptions, building characteristics were determined and building loads were calculated using the diversified loads calculation method. By having the daily data for six months for the Zachry building, the input to the CVTR, DDCV and DDVAV Microsoft Excel code were prepared for starting the simulation. The air handling units for the Zachry building are Dual Duct Variable Air Volume (DDVAV) systems. The calibration procedure has been used to compare the calibration signatures with characteristic signatures in order to determine which input variables need to be changed to achieve proper calibration. Calibration signatures are the difference between measured energy consumption and simulated energy consumption as a function of temperature. Characteristic signatures are the energy consumption as a function of temperature obtained by changing the value of input variables of the system. The base simulated model of the DDVAV system has been changed according to the characteristic signatures of the building and adjusted to get the closest result to the measured data. The simulation method for calibration could be used for energy audits, improving energy efficiency, and fault detection. In the base model of DDVAV, without any changes in the input, the chilled water consumption had an Root Mean Square Error (RMSE) of 56.705577 MMBtu/day and an Mean Bias Error (MBE) of 45.763256 MMBtu/day while hot water consumption had an RMSE of 1.9072574 MMBtu/day and an MBE of 45.763256 MMBtu/day. In the calibration process, system parameters such as zone temperature, cooling coil temperature, minimum supply air and minimum outdoor air have been changed. The decisions for varying the parameters were based on the characteristic signatures provided in the project. After applying changes to the system parameters, RMSE and MBE for both hot and cold water consumption were significantly reduced. After changes were applied, chilled water consumption had an RMSE of 12.749868 MMBtu/day and an MBE of 3.423188 MMBtu/day, and hot water consumption had an RMSE of 1.6790 MMBtu/day and an MBE 0.12513 of MMBtu/day.Item An Investigation of Using Isochoric Data Points in the Development of Natural Gas Equation of State(2014-02-27) Khazndar, Aoubai MAccess to energy is essential for the survival of humans, and the need for energy rises continuously because of population increase and economic progress. Fossil fuels continue to play the major role in satisfying energy demand. Among the fossil fuels, natural gas is the cleanest, most available, and most useful of the energy sources. It finds extensive use in residential, commercial, electric power generation and industrial applications. Moreover, the international energy outlook report released in 2011 indicates that yearly world natural gas consumption should increase from 111 trillion cubic feet in 2008 to 169 trillion cubic feet in 2035. Recently, new natural gas reservoirs have been discovered in many places throughout the world. In 2012, the total world supplies of proved natural gas reserves were estimated to be 6,746.8 trillion cubic feet. Thus, studies on natural gas are significant to advance the technique of natural gas processing, transportation and storage. In these three sectors, an accurate knowledge of the thermodynamic properties of natural gas is essential for engineering and technical processes. Developing accurate equations of state is important, and can provide us with accurate thermodynamic properties for natural gas. In addition, developing new techniques to produce mathematical models is important to create more accurate results and to enrich this field with new ideas, which might provide progress in the future. The aim of this thesis is to demonstrate a new approach for developing an equation of state. This technique relies upon isochoric data of carbon dioxide pure component to develop mathematical models. This thesis contains nine models based upon experimental and generated data. The generated data come from REFPROP, which also provides an accurate means to adjust experimental data to true isochores. Within this thesis, a regression analysis was performed - using Polymath 6.1 - to provide mathematical structure of the equation for carbon dioxide. Results indicate that models covering vapor phase has less deviation than models covering liquid or both phases, and models developed by the generated data has less deviation than models developed by the experimental data. The deviation obtained by most of the models was less than the random error imposed upon the data. In this study, we conclude that modeling an equation of state from isochores appears to provide sufficient advantages to encourage additional studies on pure fluids and multi-component mixtures.Item The application of systems engineering to a Space-based Solar Power Technology Demonstration Mission(2012-05) Chemouni Bach, Julien; Fowler, Wallace T.; Guerra, Lisa A.This thesis presents an end-to-end example of systems engineering through the development of a Space-based Solar Power Satellite (SSPS) technology demonstration mission. As part of a higher education effort by NASA to promote systems engineering in the undergraduate classroom, the purpose of this thesis is to provide an educational resource for faculty and students. NASA systems engineering processes are tailored and applied to the development of a conceptual mission in order to demonstrate the role of systems engineering in the definition of an aerospace mission. The motivation for choosing the SSPS concept is two fold. First, as a renewable energy concept, space-based solar power is a relevant topic in today's world. Second, previous SSPS studies have been largely focused on developing full-scale concepts and lack a formalized systems engineering approach. The development of an SSPS technology demonstration mission allows for an emphasis on determining mission, and overall concept, feasibility in terms of technical needs and risks. These are assessed through a formalized systems engineering approach that is defined as an early concept or feasibility study, typical of Pre-Phase A activities. An architecture is developed from a mission scope, involving the following trade studies: power beam type, power beam frequency, transmitter type, solar array, and satellite orbit. Then, a system hierarchy, interfaces, and requirements are constructed, and cost and risk analysis are performed. The results indicate that the SSPS concept is still technologically immature and further concept studies and analyses are required before it can be implemented even at the technology demonstration level. This effort should be largely focused on raising the technological maturity of some key systems, including structure, deployment mechanisms, power management and distribution, and thermal systems. These results, and the process of reaching them, thus demonstrate the importance and value of systems engineering in determining mission feasibility early on in the project lifecycle.Item Assessing and controlling concentrations of volatile organic compounds in the retail environment(2014-05) Nirlo, Éléna Laure; Corsi, Richard L.; Siegel, Jeffrey A.Retail buildings have potential for both short-term (customer) and long-term (occupational) exposure to indoor pollutants. A multitude of sources of volatile organic compounds (VOCs) are common to the retail environment. Volatile organic compounds can be odorous, irritating or carcinogenic. Through a field investigation and modeling study, this dissertation investigates exposure to, and control of, VOCs in retail buildings. Fourteen U.S. retail stores were tested one to four times each over a period of a year, for a total of twenty-four test visits. Over a hundred parameters were investigated to characterize each of the buildings, including ventilation system parameters, and airborne pollutants both indoors and outdoors. Concentrations of VOCs were simultaneously measured using five different methods: Summa canisters, sorbent tubes, 2,4-dinitrophenylhydrazine (DNPH) tubes, a photoionization detector (PID), and a colorimetric real-time formaldehyde monitor (FMM). The resulting dataset was analyzed to evaluate underlying trends in the concentrations and speciation of VOCs, identify influencing factors, and determine contaminants of concern. A parametric framework based on a time-averaged mass balance was then developed to compare strategies to reduce formaldehyde concentrations in retail stores. Mitigation of exposure to formaldehyde through air cleaning (filtration), emission control (humidity control), and targeted dilution (local ventilation) were assessed. Results of the field study suggested that formaldehyde was the most important contaminant of concern in the retail stores investigated, as all 14 stores exceeded the most conservative health guideline for formaldehyde (OEHHA TWA REL = 7.3 ppb) during at least one sampling event. Formaldehyde monitors were strongly correlated with DNPH tube results. The FMM showed promising characteristics, supporting further consideration as real-time indicators to control ventilation and/or environmental parameters. The vast majority of the remaining VOCs were present at low concentrations, but episodic activities such as cooking and cleaning led to relatively high indoor concentrations for ethanol, acetaldehyde, and terpenoids. Results of the modeling effort demonstrated that local ventilation caused the most uniform improvements to indoor formaldehyde concentrations across building characteristics, but humidity control appeared to have a very limited impact. Filtration used under specific conditions could lead to larger decreases in formaldehyde concentrations than all other strategies investigated, and was the least energy-intensive.Item Atmospheric emissions and air quality impacts of natural gas production from shale formations(2014-08) Zavala Araiza, Daniel; Allen, David T.; Webber, Michael; McDonald-Buller, Elena; Hildebrandt Ruiz, Lea; Edgar, ThomasNatural gas is at the core of the energy supply and security debates; new extraction technologies, such as horizontal drilling and hydraulic fracturing, have expanded natural gas production. As with any energy system, however, natural gas has an environmental footprint and this thesis examines the air quality impacts of natural gas production. Greenhouse gas (GHG), criteria pollutant, and toxic emissions from natural gas production have been subject to a great amount of uncertainty, largely due to limited measurements of emission rates from key sources. This thesis reports direct and indirect measurements of emissions, assessing the spatial and temporal distributions of emissions, as well as the role of very high emitting wells and high emitting sources in determining national emissions. Direct measurements are used to identify, characterize and classify the most important sources of continuous and episodic emissions, and to analyze mitigation opportunities. Methods are proposed and demonstrated for reconciling these direct measurements of emissions from sources with measurements of ambient concentrations. Collectively, the direct source measurements, and analyses of ambient air pollutant measurements in natural gas production regions reported in this work improve the estimation, characterization, and methods for monitoring air quality implications of shale gas production.Item Characterizing the energy transfer from a thermite reaction to a target(2007-12) Burkhard, Jonathan N.; Pantoya, Michelle; James, Darryl; Berg, Jordan M.Nano-sized materials often have novel properties that drastically improve performance. Very few studies on the nano-aluminum and water combustion reaction have been done without the addition of a gelling agent. The depth at which gas fueled underwater cutting torches can be used is limited by their fuel gas storage pressure restrictions. Using a nano-aluminum and water thermite reaction as the fuel for an underwater cutting torch eliminates depth limitations and creates a unique opportunity to use ambient water from the surrounding environment as the oxidizer for the reaction. Reaction characteristics were studied with high speed video analysis in inert and oxidizing environments. The heat transfer characteristics of the nano-aluminum and water reaction were compared to baseline methylacetylene-propadiene and propane fueled torches by collecting temperature data on metal test plates with thermocouples and a high speed infrared camera. Additives, such as Teflon powder, were mixed with the original thermite reactants to improve heat transfer to the test plates from the reaction. High speed video data showed that flame propagation rates were not significantly affected by the environment surrounding the reaction. Differential scanning calorimeter data confirmed that the aluminum was reacting efficiently. Temperature data from the test plates was compared after 0.9 s of heating. Thermocouple data confirms infrared camera temperature measurements. The MAPP gas torch, propane torch, Al/water reaction, and Al/water/Teflon reaction heated the plates at an average rate of 29.3 ± 0.2, 23.1 ± 0.2, 54 ± 3, and 38 ± 1 K/s respectively. The temperature change per mass of fuel burned was calculated for each torch and reaction as 400 ± 200, 500 ± 200, 180 ± 60, and 130 ± 30 K/g respectively. The time required to reach the oxidation temperature of steel for each torch and reaction was 40 ± 20, 50 ± 30, 21 ± 9, and 30 ± 10 seconds respectively. This study concludes that the Al/water reaction could significantly improve an underwater cutting device because surrounding water could be used as the primary oxidizer, the reaction has a higher heating rate than gas fuels, and the usable depth is not limited by fuel storage pressures.Item Climate action strategies for the University of Texas at Austin(2010-05) Hernandez, Marinoelle; Eaton, David J.; Walker, Jim H.This report analyzes the current greenhouse gas emissions inventory for The University of Texas at Austin (UT-Austin), reviews the carbon reduction strategies being implemented at UT-Austin and other peer institutions, and offers recommendations for strategies that could reduce greenhouse gas emissions at UT-Austin in the future.Item Computational, theoretical investigation of materials for a sustainable energy future(2016-08) Stauffer, Shannon Kaylie; Henkelman, Graeme; Mullins, Charles B; Crooks, Richard; Hwang, Gyeong; Milliron, DeliaOver the past several decades there has been significant progress in electronic structure theory, statistical sampling algorithms and computational resources which can be leveraged to calculate fundamental properties of materials and estimate rates of relevant chemical reactions. In the following dissertation, I use computational methods to address the materials problem of a sustainable energy future. Energy storage technologies have played a vital role in the mobile-technology revolution and the transition to utilize more sustainable energy sources; however improvements to the energy density, charge/discharge rate, and safety of rechargeable batteries are needed to realize the ambitious goals of fully electric vehicles and on-grid storage in areas with intermittent, renewable power sources. Li-ion batteries, in general, have a potential to fulfill these demands. In the following work, a new, high energy density electrode material with little capacity loss is considered. Additionally, the complex interaction between an electrode/electrolyte model system is considered in a potential dependent computational framework. Having a sustainable energy future also means utilizing energy-efficient processing in industrial scale applications. Separation processes use roughly 12% of all energy consumed in the United States due to energy-intensive thermal separation techniques. A final study looks at an alloy catalysts for the separation of ethylene from ethane/ethylene mixtures. A unique selectivity property was discovered that may help design catalysts to replace thermal separation of gases.Item Designing a Real-time Strategy Game about Sustainable Energy Use(2011-08-08) Doucet, Lars AndreasThis thesis documents the development of a video game about sustainable energy use that unites fun with learning. Many other educational games do not properly translate knowledge, facts, and lessons into the language of games: mechanics, rules, rewards, and feedback. This approach differs by using game mechanics in new ways to express lessons about energy sustainability. This design is based on the real time strategy (RTS) genre. Players of these types of games must manage economic problems such as extracting, refining, and allocating resources, as well as industrial problems such as producing buildings and military units. These games often use imaginative fantasy elements to connect with their audience, but also made-up economic numbers and fictional resources such as magic crystals which have little to do with the real world. This thesis' approach retains the fantasy elements and gameplay conventions of this popular genre, but uses numbers, resources, and situations based on research about real-world energy production. The intended result is a game in which the player learns about energy use simply by trying to overcome the game's challenges. In addition, a combined quantitative/qualitative study was performed, which shows that players of the game learned new things, enjoyed the game, and became more interested in the topic of energy use.Item Development of a Segregated Municipal Solid Waste Gasification System for Electrical Power Generation(2013-04-11) Maglinao, Amado LatayanGasification technologies are expected to play a key role in the future of solid waste management since the conversion of municipal and industrial solid wastes to a gaseous fuel significantly increases its value. Municipal solid waste (MSW) gasification for electrical power generation was conducted in a fluidized bed gasifier and the feasibility of using a control system was evaluated to facilitate its management and operation. The performance of an engine using the gas produced was evaluated. A procedure was also tested to upgrade the quality of the gas and optimize its production. The devices installed and automated control system developed was able to achieve and maintain the set conditions for optimum gasification. The most important parameters of reaction temperature and equivalence ratio were fully controlled. Gas production went at a rate of 4.00 kg min-1 with a yield of 2.78 m3 kg-1 of fuel and a heating value (HV) of 7.94 MJ Nm-3. Within the set limits of the tests, the highest production of synthesis gas and the net heating value of 8.97 MJ Nm-3 resulted from gasification at 725?C and ER of 0.25 which was very close to the predicted value of 7.47 MJ Nm-3. This was not affected by temperature but significantly affected by the equivalence ratio. The overall engine-generator efficiency at 7.5 kW electrical power load was lower at 19.81% for gasoline fueled engine compared to 35.27% for synthesis gas. The pressure swing adsorption (PSA) system increased the net heating value of the product gas by an average of 38% gas over that of inlet gas. There were no traces of carbon dioxide in the product gas indicating that it had been completely adsorbed by the system. MSW showed relatively lower fouling and slagging tendencies than cotton gin trash (CGT) and dairy manure (DM). This was further supported by the compressive strength measurements of the ash of MSW, CGT and DM and the EDS elemental analysis of the MSW ash.Item A dynamic model-based estimate of the potential value of a vanadium redox flow battery for energy arbitrage and frequency regulation in Texas(2012-08) Fares, Robert Leo; Webber, Michael E., 1971-; Meyers, Jeremy P.Large-scale electrochemical energy storage is a technology that is uniquely suited to integrate intermittent renewable energy sources with the electric grid on a large scale. Grid-based energy storage also has the potential to reduce costs associated with periods of peak electric demand. For these reasons, this work describes the potential applications for grid-based energy storage, and then reviews large-scale energy storage technology innovations since the development of the lead-acid battery. The potential value of grid-based battery energy storage is discussed in the context of restructured electricity markets; then, a dynamic model-based economic optimization routine is developed to gauge the potential value of a vanadium redox flow battery (VRFB) operating for wholesale energy arbitrage and frequency regulation in Texas. Based on this analysis, the relative value of a VRFB in various regions of Texas for energy arbitrage and frequency regulation is examined. It is shown that frequency regulation is an appealing application for a grid-based VRFB, with a VRFB utilized for frequency regulation service in Texas potentially worth approximately $1500/kW. Finally, the effect of a VRFB’s characteristics on its value for frequency regulation and energy arbitrage are compared, and the operational insight developed in this work is used to glean how policies to integrate a large-scale energy storage with the electricity market might be crafted.Item Ecological and evolutionary analyses of range limits and biodiversity patterns(2011-12) Behrman, Kathrine Delany; Keitt, Timothy H.; Kirkpatrick, Mark, 1956-The goal of this dissertation is to further our understanding of how spatially heterogeneous landscapes may impact the formation of range boundaries that then aggregate to form large-scale biodiversity patterns. These patterns have been analyzed from many different perspectives by ecologists, evolutionary biologist, and physiologists using a variety of different theoretical, statistical, and mechanistic models. For some species, there is an obvious abrupt change in the environment causing a range boundary. Other environments change gradually, and it is unclear why species fail to adapt and expand their range. The first chapter develops a novel theoretical model of how the establishment of new mutations allows for adaptation to an environmental gradient, when there is no genetic variation for the trait that limits the range. Shallow environmental gradients favor mutations that arise nearer to the range margin, have smaller phenotypic effects, and allow for proportionately larger expansions than steep gradients. Mutations that allow for range expansion tend to have large phenotypic effects causing substantial range expansions. Spatial and temporal variation in climatic and environmental variables is important for understanding species response to climate change. The second chapter uses a mechanistic model to simulate switchgrass (Panicum virgatum L.) productivity across the central and eastern U.S. for current and future climate conditions. Florida and the Gulf Coast of Texas and Louisiana have the highest predicted current and future yields. Regions where future temperature and precipitation are anticipated to increase, larger future yields are expected. Large-scale geographic patterns of biodiversity are documented for many taxa. The mechanisms allowing for the coexistence of more of species in certain regions are poorly understood. The third chapter employs a newly developed wavelet lifting technique to extract scale-dependent patterns from irregularly spaced two-dimensional ecological data and analyzes the relationship between breeding avian richness and four energy variables. Evapotranspiration, temperature, and precipitation are significant predictors of richness at intermediate-to-large scales. Net primary production is the only significant predictor across small-to-large scales, and explains the most variation in richness (~40%) at an intermediate scale. Changes in the species-energy relationship with scale, may indicate a shift in the mechanism governing species richness.Item Economic forecasting and optimization in a smart grid built environment(2013-08) Sriprasad, Akshay; Edgar, Thomas F.This Master’s Report outlines graduate research work completed by Akshay Sriprasad, who is supervised by Professor Tom Edgar, in the area of modeling and systems optimization for the smart grid. The scope this report includes the development and validation of strategies to elicit demand response, defined as reduction of peak demand, at the residential level, in conjunction with collaborative research efforts from the Pecan Street Research Institute, a smart grid research consortium based in Austin, TX. The first project outlined is an artificial neural network-‐based demand forecasting model, initially developed for UT’s campus cooling system and adapted for residential homes. Utilizing this forecasting model, a number of demand response-‐focused optimization studies are carried out, including optimization of community energy storage for peak shifting, and electric vehicle charging optimization to harness inexpensive night-‐time Texas wind energy. Community energy storage and electric vehicles are chosen as ideal dynamic charging media due to increased proliferation and focus of Pecan Street Research Institute on critical emerging technologies. As these two technologies involve significant capital investment, an alternative mobile application-‐based demand response strategy is outlined to complete a comprehensive portfolio of demand response strategies to suit a variety of budgets and capabilities.Item Electric vehicles and public charging infrastructure : impediments and opportunities for success in the United States(2012-05) Borden, Eric Joshua; Boske, Leigh B.; Duncan, RogerToday’s debate regarding the United States (U.S.) transportation sector has never been more important. As similar discussions embroil electricity generation, one can see the powerful forces of the status-quo pitted against growing momentum behind alternatives. The electric vehicle (EV) finds itself somewhere in the middle of the debate, as a possible alternative to the conventional vehicle (CV). As demonstrated in this report, electric vehicles are neither new nor technologically infeasible. Current circumstances have initiated what appears to be a revival of the EV – this includes years of high oil prices, geopolitical instability, and growing awareness of environmental concerns resulting from CV usage. Nevertheless, impediments remain. One of the most important is the prospect of building public charging infrastructure to allow drivers to use an EV like their conventional vehicle, for both long and short distances. Public charging infrastructure, however, cannot be built without some critical mass of EV’s on the road to use them – otherwise they are not economically feasible. This report analyzes various facets of both EV’s and public charging infrastructure to give the reader a clear understanding of the complex criteria that must be understood to assess EV’s in the United States. Texas is given special consideration as a case study in this report, particularly the Austin area where public charging infrastructure for EV’s is currently being implemented. Through a detailed analysis of electric vehicles and charging infrastructure, as well as the United States transportation system, this report seeks to reach conclusions over the role EV’s and public charging infrastructure should play in the future U.S. transportation system.Item Electrical and Production Load Factors(2010-07-14) Sen, TapajyotiLoad factors are an important simplification of electrical energy use data and depend on the ratio of average demand to peak demand. Based on operating hours of a facility they serve as an important benchmarking tool for the industrial sector. The operating hours of small and medium sized manufacturing facilities are analyzed to identify the most common operating hour or shift work patterns. About 75% of manufacturing facilities fall into expected operating hour patterns with operating hours near 40, 80, 120 and 168 hours/week. Two types of load factors, electrical and production are computed for each shift classification within major industry categories in the U.S. The load factor based on monthly billing hours (ELF) increases with operating hours from about 0.4 for a nominal one shift operation, to about 0.7 for around-the-clock operation. On the other hand, the load factor based on production hours (PLF) shows an inverse trend, varying from about 1.4 for one shift operation to 0.7 for around-the-clock operation. When used as a diagnostic tool, if the PLF exceeds unity, then unnecessary energy consumption may be taking place. For plants operating at 40 hours per week, the ELF value was found to greater than the theoretical maximum, while the PLF value was greater than one, suggesting that these facilities may have significant energy usage outside production hours. The data for the PLF however, is more scattered for plants operating less than 80 hours per week, indicating that grouping PLF data based on operating hours may not be a reasonable approach to benchmarking energy use in industries. This analysis uses annual electricity consumption and demand along with operating hour data of manufacturing plants available in the U.S. Department of Energy?s Industrial Assessment Center (IAC) database. The annual values are used because more desirable monthly data are not available. Monthly data are preferred as they capture the load profile of the facility more accurately. The data there come from Industrial Assessment Centers which employ university engineering students, faculty and staff to perform energy assessments for small to medium-sized manufacturing plants. The nation-wide IAC program is sponsored by the U.S. Department of Energy.Item Encoding serial data for energy-delay-product and energy minimization(2009-05-15) Ekambavanan, SasidharanSerial or parallel buses are widely used to communicate information in most electronic devices. The energy consumed by bus interconnects may comprise a signi?cant portion of the overall energy consumption of the device. Hence, techniques to reduce the energy consumption of bus interconnects have become an important area of research. One common method adopted to reduce energy is Bus Encoding, where redundant bits are added to the original data stream either in time or space to reduce the energy consumption. In this thesis, a novel bus encoding technique, called the Multiple Codebook Approach (MCA), is presented to reduce the Energy-Delay-Product (EDP) and Energy for data transmission over serial buses. For any symbol that is to be transmitted on the bus, the best code is selected (from an EDP or energy minimization standpoint) from among a set of codebooks. In particular, the implementation utilizes 3 codebooks. To minimize EDP, the codeword for each symbol is selected based on the product of the number of transitions resulting from its transmission in a serial manner, and the codeword length. To minimize energy, the codeword for each symbol is selected based on the number of transitions alone. The MCA is compared with other reported techniques in the literature, and the results are quite promising. The MCA achieves a 11% improvement in EDP and 3% improvement iv in Energy over the best approach known for serial data transmission, which was reported by Macii and others.Item Energy and environmental contexts of cities, transportation systems, and emerging vehicle technologies : how plug-in electric vehicles and urban design influence energy consumption and emissions(2013-12) Nichols, Brice G.; Kockelman, KaraThis thesis is divided into two parts. The first evaluates the role of the built environment in life-cycle energy consumption, by comparing different neighborhood and city styles. Through a holistic modeling and accounting framework, this work identifies the largest energy-consuming sectors, among residential and commercial buildings, personal vehicles and transit trips, and supporting infrastructure (roads, sidewalks, parking lots, water pipes, street lighting). Life-cycle energy calculations include operational energy use (e.g., gasoline for vehicles, electricity and natural gas for buildings) and embodied energy used to produce materials and construct buildings and infrastructure. Case study neighborhoods in Austin, Texas, and larger-scale regional models suggest that building energy demands comprise around 50% of life-cycle energy demands, while transportation demands (from driving and infrastructure alike) contribute around 40%, across all cases. However, results also suggest that population density and average residential unit size play a major role in defining per-capita energy consumption. Operational demands made up about 90% of life-cycle energy demands, suggesting that v most urban energy savings can be obtained from reduced personal vehicle trips and more efficient vehicles and buildings. Case study comparisons suggest that neighborhoods and regions with greater density and higher share of multi-family housing units tend to reduce operational (and thus life-cycle) energy demands with less travel demand and decreased home and work energy use, per capita. The second part of this modeled plug-in electric vehicle (PEV) emissions impacts in Texas, by considering four possible vehicle adoption scenarios (where PEVs make up 1, 5, 10, and 25% of total passenger vehicles). The analysis anticipates PEV electricity demand and emissions rates, based on current Texas power grid data. Results indicate that PEV emissions depend significantly on which specific power plants are used to power the vehicles, but that PEVs' average per-mile emissions rates for NO[subscript x], PM, and CO₂ are all likely to be lower than today's average passenger car, when today's average mix is used. Power produced from 100% coal plants could produce 14 times as much NO[subscript x], 3,200 times as much SO₂, nearly 10 times as much CO₂ and CO₂eq, 2.5 times as much PM₁₀, and VOCs, and nearly 80 times the NO₂ compared to a grid with 100% natural gas plants.Item Energy intensity ratios as net energy measures for selected countries 1978-2010(2013-12) Maxwell, John Paul; King, Carey Wayne, 1974-; Zarnikau, Jay William, 1959-Stated simply, this thesis focuses on the relationship between energy and the economy. Using the foundation of King 2010, this analysis expands the scholarship from a U.S. focus to perform Energy Intensity Ratio analysis on forty-four countries for the time period 1978-2010. There are four fuels examined: coal, natural gas, crude oil and electricity. Using both the price and expenditures based Energy Intensity Ratio methods, outputs for each fuel in any applicable sector was determined. In addition, this work compiles an estimate of the total energy expenditures for the majority of the world. By examining the overall expenditures of gross domestic product spent on energy, the data showed two points in time where energy appears to become a constraint on growth. Though this thesis does not answer the question directly as to whether an increase in energy expenditures “causes” an increase in economic growth, or whether an increase in economic growth “causes” an increase in energy expenditures, the research shows that vi there may be a “threshold” effect whereby as energy expenditures become a greater share of output, the ability of economic growth to take place is affected.Item Energy Piles in Cooling Dominated Climates(2014-04-10) Akrouch, GhassanAir pollution is one of the main environmental problems mankind faces in the 21^(st) century caused by to the extensive use of fossil fuels. One of the opportunities to overcome this problem is to develop new technologies and methods to profit from the energy stored in the ground. A promising high-efficiency technology for the thermal control of buildings is the shallow geothermal energy. This technology is growing rapidly because it consumes less conventional energy for operation, which in turn results in fewer CO_(2) emissions. This technology harnesses constant and moderate ground temperature for thermal control of a building using foundation piles. Outside air temperature changes with the season, while ground temperature remains moderate and constant. In summer, ground temperature is lower than air temperature, and so the ground may be used as a heat sink. The opposite is true in winter; the ground becomes a heat source. This technology is used efficiently in cold, heating dominated climates. Could this be true in hot, cooling dominated climates? To achieve the ultimate goal and answer the above question, this study considered the different elements of a full SGES, namely: soil, climate, energy pile, and ground source heat pump. First, The need for a new, easy, and quick in-situ method to thermally characterize soils lead to the development of the Thermal Cone Test. Second, the soil-climate interaction and its effect on the thermodynamic efficiency of energy piles was an important factor to consider, where the decrease in soil saturation leads to a decrease in the heat exchange rate of energy piles. Third, the thermal use of foundation pile changes the pile and surrounding soil temperature where both materials are temperature dependent. This change in temperature leads to a change in the mechanical behavior of energy piles. Fourth, a full-scale test on installed and instrumented energy piles group was needed to understand the thermodynamics of a full system and to provide experimental data for a full economic study. Finally, this study was capped by an economic analysis to evaluate the cost, benefits, payback period, and feasibility of SGES in cooling dominated climates. The study presented in this dissertation found that integrating energy piles in heating and cooling systems in hot, cooling dominated climates could be economical and environmentally friendly solution, but attention should be paid to the thermodynamic efficiency of the system when unsaturated soil layer is encountered, and to the long term mechanical behavior of foundation piles in high plasticity clay where additional settlement could take place resulting from the increased creep rate caused by soil heating.
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