Dissertations / Theses on the topic 'Water and Energy limited'
To see the other types of publications on this topic, follow the link: Water and Energy limited.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Water and Energy limited.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Tobin, Erik, and Linnéa Tjernström. "Potential for cultivation of Miscanthus x Giganteus for biofuel production in different climate zones : with a changing climate and limited water resources." Thesis, KTH, Industriell ekologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-139099.
Full textAbstract:
Miscanthus Giganteus is a rapidly growing perennial grass utilizing C4 photosynthesis that is a promising candidate as a raw resource for “second generation” biofuel production. This study seeks to determine the long-term sustainability, from a water balance perspective, of cultivating this plant in different climate zones. CoupModel, a model for the soil-plant-atmosphere system, is utilized to model M. Giganteus and simulate its cultivation over a 30-year period at four sites in Europe, each representing a different climate zone. A future climate scenario building on historical climate data together with projections for monthly changes in temperature and precipitation, as modeled by the HadCM3 global climate model in the A2 emission scenario, is then created and used for another simulation at each site. The growth, yields, and water balances in each simulation are analyzed and compared. The highest yields and water use efficiencies are achieved in the warmest climates, but the most sustainable zones when taking water balance into account are the more humid ones. The humid continental, Dfb, zone and the humid subtropical, Cfa, zone are determined to be sustainable in the long-term for cultivation of M. Giganteus.Miscanthus Giganteus är ett snabbväxande perennt gräs med C4-fotosyntes samt en lovande kandidat som resurs i tillverkandet av andra generationens biobränslen. Denna studie syftar till att bestämma den långsiktiga hållbarheten av odling av denna växt i olika klimatzoner ur ett vattenbalansperspektiv. CoupModel, en datamodell som simulerar systemet “jord-planta-atmosfär”, används för att simulera M. Giganteus och dess tillväxt över en 30-årsperiod för fyra platser i Europa vilka alla representerar en klimatzon. Ett framtida klimatscenario som bygger på historisk klimatdata tillsammans med projektioner för framtida månatliga förändringar i temperatur och nederbörd, framtaget av HadCM3 för IPCC:s utsläppsscenario A2, tas sedan fram och används för att göra ytterligare en simulering för varje plats. Plantans tillväxt, skörd och vattenbalans för varje simulation analyseras och jämförs. De högsta skördarna och högst vattenanvändningseffektivitet uppnås i de varmaste klimaten, men de mest hållbara zonerna för odling av M. Giganteus när vattenbalansen tas hänsyn till är zonerna med mest nederbörd. Dfb-zonen, med fuktigt inlandsklimat, och Cfa-zonen med fuktigt subtropiskt klimat bedöms vara långsiktigt hållbara för odling av M. Giganteus.
2
Markwell, Darryl. "Improvements in sustainable energy and water practice in the food processing industry : an in depth analysis of the manufacture of Ghee at the Butter Producers' Cooperative Federation Limited, Brisbane." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/27661/1/Darryl_Markwell_Thesis.pdf.
Full textAbstract:
This thesis is a documented energy audit and long term study of energy and water reduction in a ghee factory. Global production of ghee exceeds 4 million tonnes annually. The factory in this study refines dairy products by non-traditional centrifugal separation and produces 99.9% pure, canned, crystallised Anhydrous Milk Fat (Ghee). Ghee is traditionally made by batch processing methods. The traditional method is less efficient, than centrifugal separation.
An in depth systematic investigation was conducted of each item of major equipment including; ammonia refrigeration, a steam boiler, canning equipment, pumps, heat exchangers and compressed air were all fine-tuned. Continuous monitoring of electrical usage showed that not every initiative worked, others had pay back periods of less than a year. In 1994-95 energy consumption was 6,582GJ and in 2003-04 it was 5,552GJ down 16% for a similar output.
A significant reduction in water usage was achieved by reducing the airflow in the refrigeration evaporative condensers to match the refrigeration load. Water usage has fallen 68% from18ML in 1994-95 to 5.78ML in 2003-04.
The methods reported in this thesis could be applied to other industries, which have similar equipment, and other ghee manufacturers.
3
Markwell, Darryl. "Improvements in sustainable energy and water practice in the food processing industry : an in depth analysis of the manufacture of Ghee at the Butter Producers' Cooperative Federation Limited, Brisbane." Queensland University of Technology, 2005. http://eprints.qut.edu.au/27661/.
Full textAbstract:
This thesis is a documented energy audit and long term study of energy and water reduction in a ghee factory. Global production of ghee exceeds 4 million tonnes annually. The factory in this study refines dairy products by non-traditional centrifugal separation and produces 99.9% pure, canned, crystallised Anhydrous Milk Fat (Ghee). Ghee is traditionally made by batch processing methods. The traditional method is less efficient, than centrifugal separation.
An in depth systematic investigation was conducted of each item of major equipment including; ammonia refrigeration, a steam boiler, canning equipment, pumps, heat exchangers and compressed air were all fine-tuned. Continuous monitoring of electrical usage showed that not every initiative worked, others had pay back periods of less than a year. In 1994-95 energy consumption was 6,582GJ and in 2003-04 it was 5,552GJ down 16% for a similar output.
A significant reduction in water usage was achieved by reducing the airflow in the refrigeration evaporative condensers to match the refrigeration load. Water usage has fallen 68% from18ML in 1994-95 to 5.78ML in 2003-04.
The methods reported in this thesis could be applied to other industries, which have similar equipment, and other ghee manufacturers.
4
Lukamba-Muhiya, Jean-Marc. "Solar water heaters in South Africa : limits and prospects." Master's thesis, University of Cape Town, 2003. http://hdl.handle.net/11427/6928.
Full textAbstract:
Bibliography: leaves 58-60.The objective of this study was to investigate the use of solar water healers (SWH) in South Africa, and identify policies and measures that would promote their use. It has been found that conditions are appropriate for the development and use of SWH in South Africa. but the current market for this technology still remains small. The findings of survey data collected in Lwandle shows that the interviewees appreciate the use of SWH technology provided by the local authorities. However, they complained of problems during winter, as there was no backup system for these units. This was considered as one of the limitations of the project. A comparative analysis between solar home systems (SHS) and solar water heaters in South Africa was made. The findings showed that SHS is well disseminated compared to SWH. The electrification programs in the country accelerated the dissemination of SHS. Government and Eskom are fully committed to the project with significant investments on the electrification in the remote areas. On the other hand, SWH were not financially or subsidised by the government. International donors and NGO's are still promoting the use of this technology. These two technologies are still expensive for many people in South Africa. Furthermore, SHS were subsidised while SWH were not and this has affected the dissemination of SWH in the country. This study gives some recommendations for policies and measures for the future wider dissemination of SWH in South Africa.
5
Antonelli, Anna Giulia. "An experimental study of water BLEVE." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textAbstract:
A BLEVE is a physical explosion characterized by the sudden expansion of a liquefied gas under pressure and the vapor space above it. In this work, the analysis of a set of water BLEVE experiments was carried out both in terms of data processing and numerical modelling. The main purpose of the project was to investigate safety implications of a pipe rupture containing superheated water that may affect a steam generation system in a nuclear or chemical plant. The experimental campaign consisted in 27 explosive tests in which an instantaneous depressurization of the content was enabled by the use of a calibrated rupture disk. A flange calibrated for different dimensions of the releasing orifice was incorporated in the prototype to replicate a pipe failure for various nominal sizes. The analysis primarily focused on the pressure field distribution generated in the surroundings, in the form of multiple shock waves. First observations came directly from high-speed pressure data recorded, showing a high directionality of the blast, stronger in the vertical direction, and the independence of the lead shock on the initial liquid fill level. The intensity of the overpressure of the lead shock was found to be increasingly correlated with the opening size. Available theoretical methods were used to preliminarily estimate the first overpressure peak. Models based on real gas behaviour and adiabatic irreversible expansion gave the best approximation of the vertical overpressure, providing an energy conversion factor (energy contributing to the blast overpressure over the total expansion energy) comparable with values found in the literature. A few CFD simulations were then performed under a shock tube configuration to validate the widely accepted assumption that the lead pressure peak is exclusively depending on the expansion of the pressurized vapor space.
6
Benichou, Léo. "Future Energy Supply, Simulations with Limited Resources." Thesis, KTH, Energi och klimatstudier, ECS, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-43733.
Full textAbstract:
Many different organizations publish energy scenarios, from International Energy Agencyto oilproducers, but also independent academic institutions or experts. Each of these scenarios presentsome particularities. They may also reflect the interests of the institutions producing them. Ifpolicy makers are to safely rely on some scenarios for planning and analysis, there is clear needfor awareness rising regarding energy scenarios and, more generally, the future energy constraint. The Shift Project think tank addresses energy and climate change constraints in the modern world.The double degree thesis work presented in this report is the result of a five month internshipwith the Shift Project. The work was dedicated to, on the one hand, the implementation of an onlineinformation platform gathering long term historical data and energy scenarios and, on the otherhand, the development of an analytical framework for energy scenarios. These tools bring a betterunderstanding of published scenarios first by providing a unique overview of the whole ‘scenariolandscape’ allowing making comparison on relative scales and questioning their credibility. Theobjective is to increase transparency around the assumptions and meaning of the scenarios. Thetools produced will help decision makers by providing transparent material and operative filters inthe wide information base of energy scenarios. Ultimately, they help highlight the keyissuesinfluencing the global energy agenda.
7
Savage, Christopher. "Derivation of line charge algorithms for Alpine Energy Limited." University of Canterbury. Engineering, 1997. http://hdl.handle.net/10092/9166.
Full textAbstract:
This report documents the work performed during 1997 by the author developing and examining possible line charge algorithms to be applied to the Alpine Energy Limited electrical distribution network. A database is created that enables three existing databases used by Alpine to be connected, allowing correlation of information across the databases. The most important effect of this is the ability to calculate the value of each segment in the network.
A software package is created that performs the above action and allows the capital cost recovery from the network (in the form of line charges) to be calculated using a series of over ten thousand possible asset-based and installation-based methods.
The software is highly adaptable and allows line charge investigations of a very diverse nature. Performance levels of assets may be calculated, along with identification of which customers in the network are being subsidised, and to what extent.
All files used by and created by the software are in an easy to read, text based format.
In the case of program output files, Microsoft Excel is the recommended package for analysis.
In preparation for a possible move to a GIS based system at Alpine, the software has been designed to allow changes to the input files that would result from a move away from Gentrack without a major re-work to the software package. While the database created allows the asset register to be linked into a GIS environment.
Algorithms have been built into the software that automatically check the validity of the database created for this project, enabling relatively straight-forward updating of this database.
8
Nilsson, Hanna, and Sandra Johansson. "Renewable energy water pump." Thesis, University of Skövde, School of Technology and Society, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:his:diva-4171.
Full textAbstract:
Målet med det här projektet är att bygga ett tillförlitligt pumpsystem som inte är beroende av elektricitet eller icke förnyelsebara bränslen. Pumpen ska klara att pumpa 50-100 liter per dygn till en höjd av 10 meter. Konstruktionen ska placeras i indianbyn El Vergel i Amazonas, Colombia. Pumpen ska pumpa orent vatten till vattenreningstunnor de månader som invånarna i byn inte har tillgång till regnvatten.
Olika koncept arbetades fram och utvärderades. Det som valdes var en cykeldriven vattenpump, vilken uppfyllde alla krav.
Pumpens axel är kopplad till bakhjulets fälg med en kilrem. När tramporna snurrar så överförs kraften från det främre kugghjulet till det bakre med cykelkedjan och sen med kilremmen från fälgen till pumpaxeln. Konstruktionen är enkel och den är lätt att laga om den går sönder. Resultaten är en tillförlitlig pump som pumpar med ett jämt flöde.
9
Teletar, Ä°brahim Emre. "Coding and multiaccess for the energy limited Rayleigh fading channel." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14759.
Full text
10
Alam, Ahmad Mahbubul. "Energy efficiency-spectral efficiency tradeoff in interference-limited wireless networks." Thesis, Rennes, INSA, 2017. http://www.theses.fr/2017ISAR0028/document.
Full textAbstract:
L'une des stratégies utilisée pour augmenter l'efficacité spectrale (ES) des réseaux cellulaires est de réutiliser la bande de fréquences sur des zones relativement petites. Le problème majeur dans ce cas est un plus grand niveau d'interférence, diminuant l'efficacité énergétique (EE). En plus d'une plus grande largeur de bande, la densification des réseaux (cellules de petite taille ou multi-utilisateur à entrées multiples et sortie unique, MU-EMSO), peut augmenter l'efficacité spectrale par unité de surface (ESuS). La consommation totale d'énergie des réseaux sans fil augmente en raison de la grande quantité de puissance de circuit consommée par les structures de réseau denses, réduisant l'EE. Dans cette thèse, la région EE-SE est caractérisé dans un réseau cellulaire hexagonal en considérant plusieurs facteurs de réutilisation de fréquences (FRF), ainsi que l'effet de masquage. La région EE-ESuS est étudiée avec des processus de Poisson ponctuels (PPP) pour modéliser un réseau MU-EMSO avec un précodeur à rapport signal sur fuite plus bruit (RSFB). Différentes densités de station de base (SB) et nombre d'antennes aux SB avec une consommation d'énergie statique sont considérées.Nous caractérisons d'abord la région EE-SE dans le réseau cellulaire hexagonal pour différentes FRF, avec et sans masquage. Avec le masquage en plus de la perte de propagation, la mesure de coupure ε-EE-ES est proposée pour évaluer les performances. Les courbes EE-ES présentent une grande partie linéaire, due à la consommation de puissance statique, suivie d'une forte diminution de l'EE, puisque le réseau est homogène et limité par les interférences. Les résultats montrent qu'un FRF de 1 pour les régions proches de la SB et des FRF plus élevés dans la région plus proche du bord de la cellule améliorent le point optimal du EE-ES. De plus, un meilleur compromis EE-ES peut être obtenu avec une valeur plus élevée de coupure. En outre, un FRF de 1 est le meilleur choix pour une valeur élevée de coupure en raison d'une réduction du rapport signal sur interférence plus bruit (RSIB).Les précodeurs sont utilisés en liaison descendante des réseaux cellulaires MU-EMSO à accès multiple par division spatiale (AMDS) pour améliorer le RSIB. La géométrie stochastique a été utilisée intensivement pour analyser de tels systèmes complexes. Nous obtenons une expression analytique de l'ESuS en régime asymptotique, c.-à-d. nombre d'antennes et d'utilisateurs infinis, en utilisant des résultats de matrices aléatoires et de géométrie stochastique. Les SBs et les utilisateurs sont modélisés par deux PPP indépendants et le précodage RSFB est utilisé. L'EE est dérivée d'un modèle de consommation de puissance linéaire. Les simulations de Monte Carlo montrent que les expressions analytiques sont précises même pour un nombre faible d'antennes et d'utilisateurs. De plus, les courbes d'EE-ESuS ont une grande partie linéaire avant une forte décroissante de l'EE, comme pour les réseaux hexagonaux. Les résultats montrent également que le précodeur RSFB offre de meilleurs performances que le précodeur forçage à zéro (FZ), qui est typiquement utilisé dans la literature. Les résultats numériques pour le précodeur RSFB montrent que déployer plus de SBs ou d'antennes aux BSs augmente l'ESuS, mais que le gain dépend du rapport des densités SB-utilisateurs et du nombre d'antennes lorsque la densité de l'utilisateur est fixe. L'EE augmente seulement lorsque l'augmentation de l'ESuS est plus importante que l'augmentation de la consommation d'énergie par unité de surface. D'autre part, lorsque la densité d'utilisateur augmente, l'ESuS dans la région limitée par les interférences peut être améliorée en déployant davantage de SB sans sacrifier l'EE et le débit ergodique des utilisateursOne of the used strategies to increase the spectral efficiency (SE) of cellular network is to reuse the frequency bandwidth over relatively small areas. The major issue in this case is higher interference, decreasing the energy efficiency (EE). In addition to the higher bandwidth, densification of the networks (e.g. small cells or multi-user multiple input single output, MU-MISO) potentially increases the area spectral efficiency (ASE). The total energy consumption of the wireless networks increases due to the large amount of circuit power consumed by the dense network structures, leading to the decrease of EE. In this thesis, the EE-SE achievable region is characterized in a hexagonal cellular network considering several frequency reuse factors (FRF), as well as shadowing. The EE-ASE region is also studied using Poisson point processes (PPP) to model the MU-MISO network with signal-to-leakage-and-noise ratio (SLNR) precoder. Different base station (BS) densities and different number of BS antennas with static power consumption are considered.The EE-SE region in a hexagonal cellular network for different FRF, both with and without shadowing is first characterized. When shadowing is considered in addition to the path loss, the ε-SE-EE tradeoff is proposed as an outage measure for performance evaluation. The EE-SE curves have a large linear part, due to the static power consumption, followed by a sharp decreasing EE, since the network is homogeneous and interference-limited. The results show that FRF of 1 for regions close to BS and higher FRF for regions closer to the cell edge improve the EE-SE optimal point. Moreover, better EE-SE tradeoff can be achieved with higher outage values. Besides, FRF of 1 is the best choice for very high outage value due to the significant signal-to-interference-plus-noise ratio (SINR) decrease.In downlink, precoders are used in space division multiple access (SDMA) MU-MISO cellular networks to improve the SINR. Stochastic geometry has been intensively used to analyse such a complex system. A closed-form expression for ASE in asymptotic regime, i.e. number of antennas and number of users grow to infinity, has been derived using random matrix theory and stochastic geometry. BSs and users are modeled by two independent PPP and SLNR precoder is used at BS. EE is then derived from a linear power consumption model. Monte Carlo simulations show that the analytical expressions are tight even for moderate number of antennas and users. Moreover, the EE-ASE curves have a large linear part before a sharply decreasing EE, as observed for hexagonal network. The results also show that SLNR outperforms the zero-foring (ZF) precoder, which is typically used in literature. Numerical results for SLNR show that deploying more BS or a large number of BS antennas increase ASE, but the gain depends on the BS-user density ratio and on the number of antennas when user density is fixed. EE increases only when the increase in ASE dominates the increase of the power consumption per unit area. On the other hand, when the user density increases, ASE in interference-limited region can be improved by deploying more BS without sacrificing EE and the ergodic rate of the users
11
Rabie, Ahmed Ibrahim El Said. "Nonlinear estimation of water network demands form limited measurement information." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3132.
Full text
12
Collins, Daniel B. G. (Daniel Benjamin Gardiner) 1976. "Geomorphology and ecohydrology of water-limited ecosystems : a modeling approach." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38559.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.Includes bibliographical references (p. 117-129).
The role of vegetation in shaping landforms and how these landforms respond to disturbances are the subjects of this work. A numerical model is developed to help develop a mechanistic understanding of the hydrological, ecological and geomorphic interactions in water-limited ecosystems. The growth of vegetation suppresses increases in runoff, thus reducing erosion efficiency and increasing topographic slopes as rainfall increases in dry climates. Moving along a climatic gradient to wetter climates leads to the point where the effect of vegetation is overwhelmed by increasing runoff, thus erosion efficiency increases and slopes decrease. This transition in vegetation controls translates into a minimum in drainage density for a semi-arid climate. Erosion efficiency is also affected by down-slope increases in vegetation, fostered by subsurface flow, an effect that reduces channel concavity. Plant characteristics also play a role in erosion by changing the variability of the vegetative effects. Comparing regions with the same fractional vegetation cover, those with faster growing or deeper rooted plants have greater erosion efficiencies.
(cont.) The landforms' responses to disturbances depend largely on the recovery time, which in turn depends on the climate and successional characteristics of the vegetation. The erosional response to sustained changes in mean annual rainfall depends on the magnitude and direction of the change as well as on the mean rainfall prior to the change. This means that landscapes most sensitive to erosion differ depending on whether rainfall increases or decreases. Hence, a landscape's sensitivity to erosion is a function of present state as well as change in climate. A second model explores the ecohydrological determinants of plant rooting strategies. Emphasis was placed on soil moisture, and on the factors that govern moisture availability. Results are consistent with observations, and show how rooting depth may respond to environmental factors that determine infiltration depth. Roots are deeper in coarser soils, and in wetter and cooler climates. For a given total rainfall, roots are deeper also where storms are shorter and more frequent.
by Daniel B.G. Collins.
Ph.D.
13
Tony. "Link Scheduling in Rechargeable Wireless Sensor Networks with Limited Harvested Energy." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/85547.
Full textAbstract:
To date, rechargeable Wireless Sensor Networks are of great interest because sensor nodes are able to harvest energy from their environment, e.g., solar and wind, and store the harvested energy in rechargeable batteries. In this thesis, we design three greedy heuristic algorithms, i.e., LS-rWSN, LSBCC, and LSDBS, to solve three proposed link scheduling problems in rWSNs, i.e., LSHUS, LSME-1, and LSME-2. Simulations on arbitrary networks show the merits and effectiveness of the proposed solutions.
14
Nyathi, Nongezile Sibhekile. "Water conservation through energy conservation." Diss., Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-08282007-124154.
Full textAbstract:
Thesis (M.Eng.)(Chemical Engineering)--University of Pretoria, 2006.Accompanied by a CD-ROM: Appendix B. Cooling tower model results. Includes bibliographical references. Available on the Internet via the World Wide Web.
15
Savulescu, L. E. "Simultaneous energy and water minimisation." Thesis, University of Manchester, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504684.
Full text
16
Dai, Tinglong. "Inventory management in the face of a limited storage capacity /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?IELM%202006%20DAI.
Full text
17
Mohan, Janani. "Dynamic Task Allocation in Robot Swarms with Limited Buffer and Energy Constraints." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/1230.
Full textAbstract:
Area exploration and information gathering are one of the fundamental problems in mobile robotics. Much of the current research in swarm robotics is aimed at developing practical solutions to this problem. Exploring large environments poses three main challenges. Firstly, there is the problem of limited connectivity among the robots. Secondly, each of the robots has a limited battery life which requires the robots to be recharged each time they are running out of charge. Lastly, the robots have limited memory to store data. In this work, we mainly focus on the memory and energy constraints of the robot swarm. The memory constraint forces the robots to travel to a centralized data collection center called sink, to deposit data each time their memory is full. The energy constraint forces the robots to travel to the charging station called dock to recharge when their battery level is low. However, this navigation plan is inefficient in terms of energy and time. There is additional energy dissipation in depositing data at the centralized sink. Moreover, ample amount of time is spent in traveling from one end of the arena to the sink owing to the memory constraint. The goal is that the robots perform data gathering in the least time possible with the optimal use of energy. Both the energy and time spent while depositing data at the sink act as an additional overhead cost to this goal. In this work, we propose to study an algorithm to tackle this scenario in a decentralized manner. We implement a dynamic task allocation algorithm which accomplishes the goal of exploration with data gathering by assigning roles to robots based on their memory buffer and energy levels. The algorithm assigns two sets of roles, to the entire group of robots, namely: Role A is the data gatherer, a robot which does the task of workspace exploration and data gathering, and Role B is data relayer, a robot which does the task of data transportation from data gatherers to the sink. By this division of labor, the robots dynamically decide which role to choose given the contradicting goals of maximizing data gathering and minimizing energy loss. The choice of a robot to perform the task of data gathering or data relaying is the key problem tackled in this work. We study the performance of the algorithm in terms of task distribution, time spent by the robots on each task and data throughput. We analyze the behavior of the robot swarm by varying the energy constraints, timeout parameter as well as strategies for relayer choice. We also test whether the algorithm is scalable.
18
Zakkour, Paul Daniel. "Energy use versus water quality : evaluating strategies for a sustainable energy future in the water industry." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397938.
Full text
19
Wanjiru, Evan. "Optimal energy-water nexus management in residential buildings incorporating renewable energy, efficient devices and water recycling." Thesis, University of Pretoria, 2017. http://hdl.handle.net/2263/61465.
Full textAbstract:
Developing nations face insurmountable challenges to reliably and sustainably provide energy and water to the population. These resources are intricately entwined such that decisions on the use of one affects the other (energy-water nexus). Inadequate and ageing infrastructure, increased population and connectivity, urbanization, improved standards of living and spatially uneven rainfall are some of the reasons causing this insecurity. Expanding and developing new supply infrastructure is not sustainable due to sky high costs and negative environmental impact such as increased greenhouse gas emissions and over extraction of surface water. The exponentially increasing demand, way above the capacity of supply infrastructure in most developing countries, requires urgent mitigation strategies through demand side management (DSM). The DSM strategies seek to increase efficiency of use of available resources and reducing demand from utilities in the short, medium and long term.
Renewable energy, rooftop rain water harvesting, pump-storage scheme and grey water recycling are some alternatives being used to curb the insecurity. However, renewable energy and rooftop water harvesting are spasmodic in nature hampering their adoption as the sole supply options for energy and water respectively.
The built environment is one of the largest energy and water consuming sectors in the world presenting a huge potential towards conserving and increasing efficiency of these resources. For this reason, coupled with the 1970s energy challenges, the concept of green buildings seeking to, among other factors, reduce the consumption of energy and water sprung up. Conventionally, policy makers, industry players and researchers have made decisions on either resource independently, with little knowledge on the effect it would have on the other. It is therefore imperative that optimal integration of alternative sources and resource efficient technologies are implemented and analysed jointly in order to achieve maximum benefits. This is a step closer to achieving green buildings while also improving energy and water security.
A multifaceted approach to save energy and water should integrate appropriate resource efficient technology, alternative source and an advanced and reliable control system to coordinate their operation.
In a typical South African urban residential house, water heating is one of the most energy and water intensive end uses while lawn irrigation is the highest water intensive end use occasioned by low rainfall and high evaporation. Therefore, seamless integration of these alternative supply and most resource intensive end uses provides the highest potential towards resource conservation. This thesis introduces the first practical and economical attempt to integrate various alternative energy and water supply options with efficient devices. The multifaceted approach used in this research has proven that optimal control strategy can significantly reduce the cost of these resources, bring in revenue through renewable energy sales, reuse waste water and reduce the demand for grid energy, water and waste water services.
This thesis is generally divided into cold and hot water categories; both of which energy-water nexus DSM is carried out. Open-loop optimal and closed-loop model predictive (MPC) control strategies that minimize the objective while meeting present technical and operational constraints are designed. In cold water systems, open-loop optimal and MPC strategies are designed to improve water reliability through a pump storage system. Energy efficiency (EE) of the pump is achieved through optimally shifting the load to off-peak period of the time-of-use (TOU) tariff in South Africa. Thereafter, an open-loop optimal control strategy is developed for rooftop rain water harvesting for lawn irrigation. The controller ensures water is conserved by using the stored rain water and ensuring only the required amount of water is used for irrigation. Further, EE is achieved through load shifting of the pump subject to the TOU tariff. The two control strategies are then developed to operate a grey water recycling system that is useful in meeting non-potable water demand such as toilet flushing and lawn irrigation and EE is achieved through shifting of pump's load. Finally, the two control strategies are designed for an integrated rain and grey water recycling for a residential house, whose life cycle cost (LCC) analysis is carried out. The hot water category is more energy intensive, and therefore, the open-loop optimal control strategy is developed to control a heat pump water heater (HPWH) and an instantaneous shower, both powered by grid-tied renewable energy systems. Solar and wind energy are used due to their abundance in South Africa. Thereafter, the MPC strategy is developed to power same devices with renewable energy systems. In both strategies, energy is saved through the use of renewable energy sources, that also bring in revenue through sale of excess power back to the grid. In addition, water is conserved through heating the cold water in the pipes using the instantaneous shower rather than running it down the drain while waiting for hot water to arrive. LCC analysis is also carried out for this strategy.
Each of the two control strategies has its strengths. The open loop optimal control is easier and cheaper to implement but is only suitable in cases where uncertainties and disturbances affecting the system do not alter the demand pattern for water in a major way. Conversely, the closed-loop MPC strategy is more complicated and costly to implement due to additional components like sensors, but comes with great robustness against uncertainties and disturbances. Both strategies are beneficial in ensuring security and reliability of energy and water is achieved. Importantly, technology alone cannot have sustainable DSM impact. Public education and awareness on importance of energy and water savings, improved efficiency and effect on supply infrastructure and greenhouse gas emissions are essential. Awareness is also important in enabling the acceptance of these technological advancements by the society.Thesis (PhD)--University of Pretoria, 2017.
National Hub for Energy Efficiency and Demand Side Management (EEDSM)
University of Pretoria
Electrical, Electronic and Computer Engineering
PhD
Unrestricted
20
Abdallah, Adel M. "Heterogeneous Water and Energy End-Uses and Implications for Residential Water and Energy Conservation and Management." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1313.
Full textAbstract:
The thesis develops an integrated approach to model heterogeneous household water and energy end-uses and their linkages. The approach considers variations in behavioral and technological water-and-energy-use factors that affect indoor residential water- and energy-use in the U.S. Here, we use a recent, large, national, disaggregated household dataset of potable hot and cold water end-uses collected from eleven cities. We also use national energy data to estimate heterogeneous energy-uses for household water appliances including toilets, showers, faucets, clothes-washers, and dishwashers. First, probability distributions of water- and energy-use factors are identified, correlated, and compared among study sites. Then Monte Carlo simulations are used to calculate probability distributions for estimated households’ water-and-energy-uses. Finally, linear regressions are used to find the relative effects of water and energy factors on household energy-use. Results show that water and energy distributions among households are heavily skewed, with the largest 14.6% of the users consuming 30.5% and 33.1% of water and energy, respectively. Water heater dispense temperature followed by faucet flowrate have the highest relative effect on household energy-use and should be targeted to reduce household energy use. The approach improves prior homogenous and deterministic water-energy models and can help utilities select and size cost-effective collaborative water and energy conservation actions.
21
Baillie, Craig Peter. "Strategies for maximising sugarcane yield with limited water in the Bundaberg district." University of Southern Queensland, Faculty of Engineering and Surveying, 2004. http://eprints.usq.edu.au/archive/00001406/.
Full textAbstract:
[Abstract]: Sugarcane farmers in Bundaberg have had limited access to irrigation water over the last ten years. The district has the potential of growing 3.8 million tonnes of sugarcane. However, a series of dry seasons saw this reduce to 2.1 million tonnes in 2002. Compounding the effects of both dry seasons and limited water supplies has been a 30% reduction in the sugar price over this period. The irrigation requirement of sugarcane in the Bundaberg area is 8 ML/ha. The original allocated volume for sugarcane production in this area was 4.5 ML/ha (based on 1970 production areas). However, as the area under production has increased and announced allocations in each year has reduced, this allocation is now equivalent to an application volume of about 2 ML/ha A change from the traditional practice of full irrigation is required as water supplies become depleted. As there were no clear guidelines on how growers could respond to diminishing water supplies, this research investigated opportunities to fine tune irrigation practices and the performance of irrigation systems (ie. low cost solutions) that would assist growers to maximise sugarcane yield. A grower survey was initially conducted to identify current practice and opportunities for change. Field investigations focused on the performance of water winch and furrow irrigation systems, which make up 91% of the irrigated area in the district. As most of these application systems have insufficient capacity to meet crop demands opportunities to schedule irrigations were limited to start up after rain. Improvements in irrigation system performance were found to provide the greatest potential to increase sugarcane yield under conditions of limited water. Investigations identified that irrigation performance could be significantly improved through relatively minor adjustment. Field trials found that wind speed and direction significantly influenced the performance of travelling gun irrigators. Although growers were generally aware of the effects of wind, meteorological data suggested that the opportunity to operate water winches in low wind conditions is limited. Changing to a taper nozzle under moderate to high wind conditions will reduce the effect of wind on performance. This practice was found to improve the uniformity (measured by Christiansen’s Uniformity Coefficient, CU) by 16%. The grower survey indicated that there was no preference towards the use of taper nozzles in windy conditions. Additional trial work developed a relationship between the variation in water applied to the field through non uniformity and sugarcane yield. An 8% reduction in yield was determined for a 10% reduction in CU. This indicated that changing to a taper nozzle could potentially increase sugarcane yield by 15% in high wind conditions. Other settings, which also influenced uniformity, included lane spacing and gun arc angle Simple changes to the operation of furrow irrigation systems were also found to dramatically improve irrigation performance. Field measurements in combination with simulation modelling of irrigation events using SIRMOD II identified that current irrigation performance ranged in application efficiency from 45 to 99% (mean of 79%) and a distribution uniformity from 71 to 93% (mean of 82%). Both application efficiency and distribution uniformity were increased to greater than 90% and 84% respectively, except on a cracking clay soil. Improvements in application efficiency and distribution uniformity were achieved by adjusting furrow flow rate (cup size), turning the irrigation off at the right time (ie. just as it reached the end of the field) and banking the end of the field. Growers had a good understanding of the correct cut off time and were attentive to reducing run off through either banking ends or tail water return. However, growers had a poor understanding of the significance of furrow flow rate. Other opportunities to improve irrigation performance on high infiltration soils included alternate furrow irrigation and shallow cultivation practices which maintained compaction in the interspace and reduced infiltration. Soil moisture and crop growth measurements indicated that sugarcane yield could be maximised by starting the irrigation rotation earlier after rainfall (ie. at a deficit equal to the irrigation amount). These observations were modelled using the crop simulation model APSIM sugar to assess the strategy over a longer time interval and the influence of seasonal variation. Simulation modelling showed that final sugarcane yields were not sensitive to irrigation start-up strategies. Yields for the start-up strategies modelled varied by less than 5 tc/ha. This minor difference occurred as the crop yield was driven by the total amount of water available to the plant. The limited amount of irrigation water available to the plant (2 to 3 ML/ha) had only a minor effect on the water balance and no significant change to effective rainfall between strategies. The greatest difference in yield occurred between irrigation treatments when water was left over at the end of the season (9.2 tc/ha). Starting irrigation earlier after rainfall events (on a 14 day rotation) provided the greatest opportunity to use all of the available irrigation supply. By comparison, delaying the application of the first irrigation after rainfall resulted in some of the irrigation water not being applied in 30% of years.
22
JIA, Xuexiu. "EXTENDED METHODOLOGY FOR WATER RESOURCES AND WATER-RELATED ENERGY ASSESSMENT ADDRESSING WATER QUALITY." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-433451.
Full textAbstract:
Problémy s vodou, zejména její nedostatek a znečištění, ovlivňují každodenní lidský život a hospodářský vývoj. Globální změny klimatu zvyšují pravděpodobnost a četnost extrémních událostí jako jsou sucho a záplavy. Rostoucí problémy s nepravidelnou dostupností a znečištěním vody vyžadují pokročilejší metodiky hodnocení vodních zdrojů, které povedou k efektivnímu využití a hospodaření s vodou. Tato práce se zabývá rozšířenými metodikami pro hodnocení vody z pohledu její kvality a kvantity a pro hodnocení spotřeby energie a produkce emisí souvisejících s vodou. Tři hlavní metodiky jsou navrženy na základě konceptu vodní stopy (Water Footprint) a pinch analýzy vody (Water Pinch Analysis) pro posouzení kvantitativních a kvalitativních hledisek využití a spotřeby vody. Použití těchto metod je rovněž demonstrováno pomocí numerických a empirických případových studií zaměřených na hodnocení a optimalizaci využití regionálních a průmyslových vodních zdrojůDále jsou diskutovány souvislosti mezi vodou a energií (Water-Energy Nexus) za účelem analýzy problémů týkající se vody z širší perspektivy. Z pohledu vody a vodních zdrojů je provedeno počáteční zhodnocení energetické náročnosti a produkce emisí skleníkových plynů v problematice odsolování mořské vody. Výsledky prezentované v této práci navazují na současné metodiky hodnocení vodních zdrojů. Stopa dostupnosti vody (Water Availability Footprint) byla navržena pro zohlednění dopadu degradace kvality vody ve stávajících postupech pro posuzování nedostatku vody, ve kterých nebyla dříve řešena. Druhým přínosem této práce je návrh konceptu kvantitativní-kvalitativní vodní stopy (Quantitative-Qualitative Water Footprint - QQWFP), ve kterém je definována vodní stopa z pohledu nákladů a následně je stanovena v souvislosti s celkovými náklady na spotřebu vody a odstraňování kontaminantů, které se do vody dostávají v průběhu jejího využití. Vodní stopa založená na nákladech poskytuje výsledky, které jsou intuitivnější jak pro management vodních zdrojů tak i pro veřejnost. Tento přístup umožňuje lépe kontrolovat a řídit průmyslové a regionální využívání a správu vody. Třetím přínosem této práce je rozšíření pinch analýzy nedostatku vody (Water Scarcity Pinch Analysis - WSPA), ve které je aplikována pinch analýzy vody na makroúrovni se zaměřením na regionální hodnocení a optimalizaci zdrojů a využívání vody. Všechny tři navržené metody jsou zaměřeny na stanovení dopadů využití vody z hlediska jejího množství a kvality, analýzy QQWFP a WSPA také pokrývají dopady vícečetných kontaminantů. Kromě hledání řešení se tato práce také pokouší naznačit potenciální směry pro budoucí výzkum v dané oblasti. Mezi významná potenciální témata k diskuzi patří 1) pokročilejší metoda kvantifikace vlivu více kontaminantů a 2) implementace a analýza ekonomické proveditelnosti přístupů WSPA a QQWFP s lokalizovanými daty s cílem nalézt přizpůsobené řešení pro optimální využití regionální a průmyslové vody.
23
Clark, Sylvia. "Water-power and water-supply : public health as a cause of the decline of water-power." Thesis, Open University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.256256.
Full text
24
Eden, Robert David. "Water hyacinth as an energy resource." Thesis, University of Warwick, 1993. http://wrap.warwick.ac.uk/104807/.
Full textAbstract:
Water hyacinth (Eichhornia crassipes, (Mart) Solms), a floating aquatic plant, has long been recognised as a potential commercial resource but, despite many attempts, its conversion from a nuisance into an asset has not been achieved on a significant scale. The thesis is an analysis and assessment of the options for overcoming the many difficulties encountered in the use of water hyacinth. Following a literature survey, from which a process flow path for optimum use of water hyacinth is devised, the thesis leads to an evaluation of the key components of the proposed system for use of water hyacinth as a large-scale energy resource. The principle component of a system to produce energy from water hyacinth is the anaerobic digester. Trials with high-rate anaerobic digesters were conducted in Bangladesh and Thailand. In Bangladesh, with the assistance of senior personnel from the Department of Chemistry of Dhaka University, an 8.3 cubic metre, multi-stage, upflow anaerobic digester was built within the grounds of the Housing and Building Research Institute in Dhaka. Trials with this unit, and associated laboratory work, demonstrated and quantified both the need and the scope for pre-treatment of raw water hyacinth prior to anaerobic digestion. Initial experimentation in Bangladesh laid down the foundations for an understanding of water hyacinth and led to the experimental programme performed in Thailand. In Thailand, following an extensive search and selection of suitable juicing apparatus, a series of batch reactors were run with juice made from separate parts of the whole plant. These results were compared with each other and with a reactor running on juice made from whole plant. The conclusion drawn from this experimentation was that, when mechanically pre-treated, the root section of the plant will contribute more to gas production than will the stem portion. In many previous trials the root has been discarded because of its resistance to anaerobic digestion in a raw form. A multi-stage upflow anaerobic digester was conceived with inclined weir plates, intended to resist blocking of the flow paths by insoluble solids in water hyacinth juice. A series of four of these units were built on a laboratory scale and trials carried out over a period of one month. These trials demonstrated that the proposal to juice water hyacinth prior to low-solids, high-rate anaerobic digestion is one that is technically feasible. The final sections of the thesis use an economic model of the proposed system to conclude that small-scale (3 m3 biogas per day) and medium- scale (1,000 m3 biogas per day) utilisation of water hyacinth will be difficult to achieve in a commercial setting. Large-scale (above 100,000 m3 biogas per day) utilisation of water hyacinth, however, is concluded to be of significant commercial potential.
25
Gay, Alanis Leon F. "Measuring Energy Efficiency of Water Utilities." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/34231.
Full textAbstract:
Water infrastructure systems worldwide use large amounts of energy to operate. Energy efficiency efforts are relevant because even relatively small gains in efficiency have the potential to bring significant benefits to these utilities in terms of financial savings and enhanced sustainability and resiliency. In order to achieve higher efficiency levels, energy usage must be measured and controlled.
A common tool used to measure energy efficiency in water utilities and perform comparisons between utilities is metric benchmarking. Energy benchmarking scores are intended to measure how efficient water systems are among their peers, in a simple and accurate fashion. Although many different benchmarking methods are currently used, we chose to use the segregated benchmarking scores proposed by Carlson on his research report from 2007 (Carlson, 2007).
The research objective is to improve these production energy use and treatment energy use benchmarking scores by analyzing the systemâ s particular characteristics that might skew the results, such as topology, water loss and raw water quality. We propose that benchmarking metrics should be always used within a particular context for each specific utility being analyzed. A complementary score (Thermodynamic Score) was developed to provide context on how energy efficient is the utility not only compared with other utilities, but also compared with the potential maximum efficiency the utility can reach itself.
We analyzed eight utilities from Virginia to obtain production and treatment energy use benchmarking scores and also thermodynamic scores using the minimum required energy approach. Benchmarking scores were skewed in 50% of the studied utilities. This means that benchmarking scores should never be used as a black box. The thermodynamic score proved to be useful for measurement of energy efficiency of a water utility on its production phase. In addition, some utilities can detect significant financial saving opportunities using the minimum required energy analysis for production operations.Master of Science
26
Monckton, Rhiannon. "Low energy electron interactions with water." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/low-energy-electron-interactions-with-water(c807bd78-59e3-4570-be3c-34feafc01fdf).html.
Full textAbstract:
Understanding the radiation chemistry of water is important in many disciplines including the nuclear industry, astrochemistry, and medicine. In recent years, low-energy electrons have been paid much greater attention, due to their abundance and reactivity in irradiated materials. Electrons with energies < 20 eV may interact via the dissociative electron attachment (DEA) mechanism, which has been found to cause single-strand breaks in DNA.DEA in water involves the capture of a low energy electron by a neutral water molecule into an outer orbital and is generally accompanied by excitation of the H2O molecule, causing it to dissociate. The aim of this work is to study the OH radical produced in DEA to H2O using laser-induced fluorescence (LIF).A high-vacuum chamber equipped with low energy electron gun, molecular beam and laser system was built for gas-phase studies of DEA in water. LIF spectra were recorded from OH formed by dissociation of gas-phase H2O, for determination of the rotational and vibrational state distributions. In addition to the gas-phase studies, low-energy (100 eV) electron-stimulated reactions in layered H2O/CO/H2O ices were investigated using a combination of temperature-programmed desorption (TPD) and infrared reflection-absorption spectroscopy (IRAS).For CO trapped within approximately 50 mono-layers of the vacuum interface both reduction and oxidation products were observed including HCO, H2CO, H3CO and CH3OH, and CO2. Concentration profiles of CO versus film thickness showed two zones in the film: a near-surface zone of preferential oxidation, and a zone of preferential reduction deeper in the film. A Monte Carlo model was developed based on diffusion of H atoms through the ice lattice, which supported the experimental results.
27
Gutierrez, Cori Omar. "Relationship and feedback between LULC changes and hydroclimatic variability in Amazonia." Electronic Thesis or Diss., Sorbonne université, 2024. http://www.theses.fr/2024SORUS123.
Full textAbstract:
La forêt amazonienne joue un rôle essentiel en tant que régulateur du système climatique et principal puits de carbone terrestre. Il contrôle les processus hydroclimatiques et atténue les effets des sécheresses grâce au couplage végétation-atmosphère. En fait, les forêts amazoniennes peuvent potentiellement affecter les régimes de précipitations grâce à des processus biophysiques tels que le recyclage de l'eau. Cependant, ces capacités ont été réduites au cours des dernières décennies en raison des perturbations du système climat-végétation ainsi que de l'intensification des sécheresses. Cela a accentué un processus de transition biophysique d'un écosystème à prédominance forestière vers une savane. Par conséquent, compte tenu de ces complexités, il est extrêmement important de comprendre la direction des changements.À l'aide de plusieurs ensembles de données et du modèle couplé ORCHIDEE-LMDZ, cette thèse approfondit l'étude des interactions entre l'hydroclimatologie et la végétation amazonienne. En outre, il cherche à élargir notre compréhension des modifications du système végétation-atmosphère et de ses liens avec le climat et des changements du LULC. De même, en tenant compte des taux croissants de déforestation, il étudie les effets et les rétroactions résultant d'un scénario de perte forestière à grande échelle sur les processus hydrologiques.Les résultats montrent que, dans le sud-ouest de l'Amazonie, les forêts passant d'un état influencé par la disponibilité énergétique à un état dépendant de la disponibilité en eau tout au long de l'année. Pendant la saison des pluies, la croissance de la végétation est principalement influencée par la disponibilité en énergie plutôt que par la disponibilité en eau. Cependant, en dehors de cette période, les forêts réagissent positivement aux précipitations et au stockage terrestre de l'eau, ce qui suggère que la végétation dépend principalement de l'approvisionnement hydrique. Toutefois, une analyse spatiale révèle que la déforestation récente modifie ces transitions et déstabilise l'équilibre naturel du système climat-végétation.La nature de ces déséquilibres en Amazonie n'est pas complètement claire. En examinant les liens entre les flux d'eau/énergie et les conditions de végétation, nous explorons si ces changements sont inhérents au climat ou résultent de processus anthropiques. 67% du sud-ouest a connu une transition vers un état majoritairement sec en raison du climat (forçage externe), tandis que 21% a connu une transition vers un état dominé par la déforestation (forçage interne). Cependant, les moteurs externes et internes entraînent simultanément des changements. En quantifiant les forçages, nous montrons que les synergies ont amené 74% du sud-ouest de l'Amazonie à un état de stress hydrique élevé. Or, ces dernières années, 30% des changements sont strictement dominés par des forçages internes. Cela suggère que les processus internes jouent un rôle croissant dans la transition vers des états caractérisés par un stress hydrique forestier élevé, particulièrement là où la déforestation et la pression anthropique augmentent.À l'aide du modèle couplé ORCHIDEE-LMDZ, les effets de la déforestation projetée de l'Amazonie d'ici 2050 sur le cycle de l'eau et la sécheresse sont examinés. La déforestation diminue les précipitations, réduit l'évapotranspiration et augmente le ruissellement. De plus, elle accentue le stress hydrique, notamment dans le sud-ouest de l'Amazonie (retour positif). La demande en eau dans l'atmosphère, à la surface et même dans la zone racinaire du sol s'intensifie pendant la saison sèche. Pendant la saison des pluies, le déficit d'humidité atmosphérique devient encore plus aigu vers les Andes tropicales, sur la région de l'Altiplano. Ces résultats permettent de mieux comprendre les effets possibles du déboisement massif sur la disponibilité en eau et la résilience de l'Amazonie dans un contexte où les changements se produisent à un rythme accéléréThe Amazon rainforest plays a vital role by functioning as a regulator of the climate system and as the main terrestrial carbon sink. It drives hydroclimatic processes and mitigates the effects of droughts through vegetation-atmosphere coupling. Indeed, Amazon forests have the potential to impact rainfall patterns through biophysical processes like water recycling. However, these capacities have been reduced during the last decades due to disturbances in the climate-vegetation system together with the intensification of droughts. All this has accentuated a process of biophysical transition from a predominantly forested ecosystem to a Savanna. Therefore, given these complexities, understanding the direction of changes is of vital importance.Using multiple datasets and the coupled ORCHIDEE and LMDZ models, this thesis delves into the study of the interactions between Amazon hydroclimatology and vegetation. In addition, it seeks to expand our understanding of modifications in the vegetation-atmosphere system and its links with climate and LULC changes. Likewise, taking into account the increasing rates of deforestation, it investigates the effects and feedback resulting from a large-scale forest loss scenario on hydrological processes.The results show that, over the southwestern Amazon, forests undergo a transition from being influenced by energy availability to depending on water availability throughout the year. During the rainy season, vegetation growth is primarily influenced by energy availability rather than water availability. Nevertheless, outside of this period, forests respond positively to precipitation and terrestrial water storage, suggesting that vegetation is primarily dependent on water supply. However, a spatial analysis reveals that recent deforestation modifies these transitions and destabilizes the natural balance in the climate-vegetation system.The nature of these imbalances in the Amazon is not entirely clarified. Through an approach based on the relationships of water/energy fluxes and vegetation conditions over the last four decades, it is explored whether these changes are intrinsic to climate variability or are driven by anthropogenic processes. 67% of the southwestern Amazon has experienced a transition towards a predominantly dry state due to climatic factors (external forcing), while 21% has transitioned towards a state dominated by deforestation (internal forcing). However, external and internal forcings are not independent processes, as both mechanisms drive changes simultaneously. By weighing the magnitudes of these forcings, we show that the synergies have led 74% of the southwestern Amazon toward a state of greater water stress. Nevertheless, during recent years, although combined external-internal processes continue to exert significant control over changes, 30% of these are strictly dominated by internal forcing. This suggests that internal processes are playing an increasingly relevant role in the transition towards a state characterized by high forest water stress, especially in areas where deforestation and anthropogenic pressure are increasing.Using the coupled ORCHIDEE and LMDZ models, the effects of projected Amazon deforestation by 2050 on the hydrological cycle and dryness are examined. Deforestation decreases precipitation, reduces evapotranspiration and increases runoff. Furthermore, deforestation accentuates water stress especially in the southwestern Amazon (positive feedback). Water demands in the atmosphere, on the land surface and even in the soil root zone intensify during the dry season. During the wet season, the deficit of specific atmospheric humidity becomes even more acute towards the tropical Andes over the Altiplano region. These findings provide a more thorough understanding of the possible effects of massive forest removal on the water availability and resilience of the Amazon in a context where changes are occurring at an accelerated rate
28
Yu, Kevin L. "Persistent Monitoring with Energy-Limited Unmanned Aerial Vehicles Assisted by Mobile Recharging Stations." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/83493.
Full textAbstract:
We study the problem of planning a tour for an energy-limited Unmanned Aerial Vehicle (UAV) to visit a set of sites in the least amount of time. We envision scenarios where the UAV can be recharged along the way either by landing on stationary recharging stations or on Unmanned Ground Vehicles (UGVs) acting as mobile recharging stations. This leads to a new variant of the Traveling Salesperson Problem (TSP) with mobile recharging stations. We present an algorithm that finds not only the order in which to visit the sites but also when and where to land on the charging stations to recharge. Our algorithm plans tours for the UGVs as well as determines the best locations to place stationary charging stations. While the problems we study are NP-Hard, we present a practical solution using Generalized TSP that finds the optimal solution. If the UGVs are slower, the algorithm also finds the minimum number of UGVs required to support the UAV mission such that the UAV is not required to wait for the UGV. We present a calibration routine to identify parameters that are needed for our algorithm as well as simulation results that show the running time is acceptable for reasonably sized instances in practice. We evaluate the performance of our algorithm through simulations and proof-of-concept experiments with a fully autonomous system of one UAV and UGV.Master of Science
Commercially available Unmanned Aerial Vehicles (UAVs), especially multi-rotor aircrafts, have a flight time of less than 30 minutes. However many UAV applications, such as surveillance, package delivery, and infrastructure monitoring, require much longer flight times. To address this problem, we present a system in which an Unmanned Ground Vehicle (UGV) can recharge the UAV during deployments. This thesis studies the problem of finding when, where, and how much to recharge the battery. We also allow for the UGV to recharge while moving from one site to another. We present an algorithm that finds the paths for the UAV and UGV to visit a set of points of interest in the least time possible. We also present algorithms for cases when the UGV is slower than the UAV, and more than one UGV may be required. We evaluate our algorithms through simulations and proof-of-concept experiments.
29
Hoover, Joseph Hamilton. "THE ARIZONA WATER-ENERGY NEXUS: ELECTRICITY FOR WATER AND WASTEWATER SERVICES." Thesis, The University of Arizona, 2009. http://hdl.handle.net/10150/193342.
Full textAbstract:
The water-energy nexus is the dependent relationship between water and energy resources. The nexus results in complex policy and management challenges for resources that have been historically managed independently. This study quantifies electricity used for water service provision in Arizona. Employing the water use cycle as an analysis tool, this study divides municipal water use for the Tucson metropolitan area and city of Phoenix into four components. The findings suggest that energy intensity differences between Phoenix and Tucson exists due to geographic variables. The city of Phoenix and Tucson metropolitan area currently consume 1.2% of statewide electricity for water and wastewater service. Electricity demand for water and wastewater service in Tucson for 2008-2030 will be 110-131%, which is greater than the 85% electricity growth statewide. Water and wastewater agencies now face decisions regarding future plans to meet water demand and maintain a low overall energy use for service provision.
30
Sølvskudt, Ida Oyen, and Birthe Sønning. "Norwegian Marine Energy Industry : To What Extent Can Norway Develop a Marine Energy Industry with a Limited Home Market?" Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for industriell økonomi og teknologiledelse, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-21068.
Full textAbstract:
This master thesis study to what extent Norway can build a wave and tidal (marine energy) industry with a limited home market. Marine energy entails immense power potential and can become an important, infinite renewable energy source if the technology reaches grid parity. Norway has physical resources, R&D history within marine energy and need for a new industry to extend the offshore competences after the oil reserves are empty. Thus, marine energy could provide great opportunities for Norway in the future. While other countries introduce favourable demand-side policies to stimulate the development of marine energy industry, Norway only has supply-side incentives making marine power production impossible with current, immature technologies. Inexpensive hydropower and low unemployment rates lead to minimal domestic demand for marine energy, and Norwegian private actors are to a low degree involved in the industry. Thus, the limited Norwegian market for marine energy raises a question of whether Norwegian marine energy industry can evolve. In order to investigate the importance of home market in existing theory, a literature review has been conducted. As there is little theory directly related to implications of limited home markets, three theory areas have been studied in depth, namely trade theory, innovation systems and emerging industries. In addition, four mini cases on similar renewable energy industries have been studied to cover potential shortcomings in theory. The thesis is primarily based on ten focused interviews with different marine industry and surrounding industry actors. In addition, we have performed research using leading energy publications and scientific reports, as well as attended conferences on marine- and renewable energy. Our combined data provides information on the development of marine energy industry and the current status of the Norwegian system for development of renewable energy. Our findings suggest that building an industry with a limited home market could be possible, but it demands (1) willingness to develop the industry among industry and surrounding actors, (2) advantageous conditions in home nation, (3) accessible demand in foreign markets, and (4) cooperation among the industry and surrounding actors. Norway has relevant competence from the oil and gas and maritime industries as well as favourable natural resources, which could function as advantageous conditions for development of a marine industry. UK and other leading markets are in addition close and accessible to Norwegian companies. However, our findings indicate that considerable development of a marine energy industry in Norway is unlikely at this point as there is low willingness and cooperation among the Norwegian actors, leading to little collective progress. If Norway is to become a leading nation within marine energy, increased involvement and cooperation among the industry and related actors is needed to ramp up the development: - Entrepreneurs need to increase cooperation in order to drive the technology development towards commercialization. - Policy makers need to increase its focus on marine energy, develop a long-term strategy for development and communicate this to the industry and the public. - Large companies need to extend involvement in the marine energy industry in order to increase legitimacy and contribute to diminish technical and financial challenges. - Investors need to increase knowledge and involvement in marine energy and realize needs in critical stages.
31
Al-Qudah, Hussein. "Optimal irrigation management under conditions of limited water supply in the Jordan Valley." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243295.
Full text
32
McPherson, E. Gregory. "Southwestern Landscaping that Saves Energy and Water." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 1989. http://hdl.handle.net/10150/144823.
Full textAbstract:
62 pp.Illustrated guidelines for energy and water conservation for landscaping in the southwestern area of the United States, along with the landscaping design process.Includes appendix on tree, shrub and vine characteristics and requirements. (62 pages.)
33
Hartwig, Gerhard Rudolf. "Grey water reclamation utilising solar thermal energy." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85631.
Full textAbstract:
Thesis (MScEng)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: The objective of this research was to obtain clean drinkable water from treated sewage effluent by using a solar-powered distillation cycle. Technologies and concepts were borrowed from the solar desalination industry to propose a unique circular distillation cell design. From the design, a specific mathematical correlation was developed to predict the distillate mass flow rate by using only evaporation and condensation temperature as inputs. This model was incorporated into a simulation model built using Transient System Simulation software. Long-term simulations were carried out to determine the operating capabilities of the design. A prototype was successfully constructed and operated. Experimental results indicated good agreement with the mass flow rate mathematical correlation. Water quality levels were tested against the South African National Standard 241 national drinking water quality standard. Four quality parameters are outside acceptable levels. Evidence suggested that acceptable quality levels could be reached. The circular distillation cell design is a major contribution made by this research. Another contribution is the simulation model capable of predicting an output for different locations. Finally, the proposed prototype is potentially a very valuable device contributing towards the reduction of consumer demand in terms of water and energy as well as the household load on the wastewater treatment system.
AFRIKAANSE OPSOMMING: Die doel van hierdie tesis is om te beskryf hoe behandelde rioolwater deur middel van ’n son aangedrewe distillasiesisteem gesuiwer kan word om drinkbare water as eindproduk te lewer. Die nodige tegnologieë en konsepte is oorgeneem uit kommersiële sonaangedrewe ontsoutingsisteme om met ’n unieke ontwerp voorendag te kom wat uit ’n sirkelvormige natuurlike konveksie distillasiesel bestaan. Met behulp van hierdie ontwerp is ’n wiskundige korrelasie ontwikkel om die gesuiwerde water se massavloei te bepaal. Slegs die verdampings- en kondensasietemperature word as insetwaardes gebruik om die massavloei te bereken. ’n Simulasiemodel is met behulp van die Transient System Simulation programmatuur gebou. Die wiskundige korrelasie is by die simulasiemodel geïnkorporeer om langtermynsimulasies te kan uitvoer. Voorts is ’n demonstrasiemodel suksesvol gebou en aangedryf. Eksperimentele resultate toon goeie ooreenstemming met die simulasieresultate. Die gesuiwerde water se gehalte is met die nationale SANS 241 drinkwaterstandaard as maatstaf getoets. Slegs vier gehalteparameters val buite die aanvaarbare vlakke, hoewel dit blyk dat hierdie elemente wel tot aanvaarbare vlakke verlaag kan word. Hierdie navorsing se grootstet bydrae is die ontwerp van die unieke sirkelvormige distillasiesel. ’n Bykomende bydra is die aanpasbaarheid van die simulasiemodel sodat dit produksievermoë op verskillende plekke kan voorspel. Die demonstrasiemodel is ’n potensieel waardevolle ontwerp wat kan bydra tot die verlaging in verbruikersaanvraag na water en energie. ’n Ontwerp van hierdie aard kan die las wat huishoudings op suiweringaanlegte vir rioolwater plaas, verlig.
34
Lee, Sojeong. "Water and energy resource dependence and conflict." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6458.
Full textAbstract:
The main purpose of this thesis is to understand the relationship between natural resources and conflict and cooperation. In this research, I develop a theory of resource dependence focusing on water and energy resources that are important to people’s survival and national economy and security. I theorize the relationship between resource dependence and interstate conflict in two ways. First, I argue that as a state becomes more dependent on natural resources, the state is less likely to engage in conflict with other states. Resource dependence reduces conflict risks because a state with greater resource dependence does not want to lose any benefits that they currently enjoy from natural resources and as a result the potential costs of conflict increases. Second, I argue that as two states become more extensively (salience) and equally (symmetry) reliant on natural resources together, they are less likely to fight. Since they have similar benefits associated with natural resources that neither states want to lose, they have more incentives to avoid risky conflict over natural resources.
To examine my theory of resource dependence and conflict, I create an original measure of a state’s level of dependence on freshwater resources and energy resources, in particular focusing on a state’s electricity demands, areas of river basins, and values of energy resources. I also create a dyadic measure of resource dependence (salience, symmetry, and interdependence). By using river-specific conflict data from the Transboundary Freshwater Disputes Database (TFDD) and militarized interstate disputes (MIDs) data from the Correlates of War (COW) project from 1960 – 2001, I test my arguments of the relationship between a state’s resource dependence and conflict at the monadic and the dyadic levels, as well as individual level in terms of citizens’ trust in government. Empirical analyses at the monadic level show that as a state becomes more dependent on water and energy resources, the state is less likely to engage in river conflicts with other states. However, a state’s resource dependence does not influence the chances for militarized conflict in shared river basins at the monadic level. Empirical results at the dyadic level also support my theory of resource dependence and conflict: as two states in a dyad become more extensively and equally dependent on water and energy resources, they are less likely to experience diplomatic conflicts and militarized interstate disputes. While high levels of resource dependence (demand and supply) reduce conflict at the monadic and dyadic levels, I find that pairs of countries with symmetric levels of resource dependence face higher conflict risks. In terms of trust in government, I find that a state’s level of resource dependence has positive impacts on people’s perception toward the government.
My dissertation makes several contributions to the field of resource conflict and international relations. This study is one of the first efforts to look at the degree of dependence on natural resources to understand the variation in conflict and cooperation over natural resources. The chances for interstate conflict varies under the same scarcity (e.g. lack of water) or abundance resource conditions (e.g. both states oil producers). By looking at a state’s level of resource dependence varying over time and space, this research can uncover more detailed understandings about the states or dyads most likely to fight over water and energy resources. This study is one of the first to use a state’s electricity needs as a measure to capture a state’s dependence on natural resources. Electricity is crucial to a state’s political economy and people’s survival. Hence, by looking at the level of electricity demands by a state regarding water and energy resources, we can understand how much a state depends on natural resources. Furthermore, this research sheds light on how a state’s dependence on natural resources affect people’s trust in government, beyond previous study’s resource curse argument. Different from the previous researchers’ pessimistic diagnosis on natural resources, a state’s high level of dependence on natural resources can contribute to people’s better perception toward the government. Theoretically, my theory of resource dependence and conflict establishes a direct connection between a relatively new field of natural resource conflict with well-developed and classic International Relations and Political Economy research. Practically, my research can help policy makers figure out where and when resource conflict is most likely between countries. Policy makers can develop policy provisions properly to avoid conflict and to encourage peaceful and cooperative resolution over natural resources between countries.
35
PICINARDI, Alberto. "Cogeneration of cooling energy and fresh water." Doctoral thesis, Università degli studi di Bergamo, 2011. http://hdl.handle.net/10446/883.
Full textAbstract:
A design simulation of the cogeneration system allowed to chose the best HD unit configuration, while a TRNSYS off-design simulation revealed the main design variables on which to focus the optimization. The optimization study on the design variables was performed by GenOpt, a generic optimization program which minimizes an objective function with respect to multiple variables. This study has been carried out on different objective functions and reveals that maximizing the production of cooling energy means damaging the fresh water production. A compromise solution has been chosen to balance the contrast between cooling energy and fresh water production.
36
PICINARDI, Alberto. "Cogeneration of cooling energy and fresh water." Doctoral thesis, Università degli studi di Bergamo, 2011. http://hdl.handle.net/10446/222125.
Full textAbstract:
A design simulation of the cogeneration system allowed to chose the best HD unit configuration, while a TRNSYS off-design simulation revealed the main design variables on which to focus the optimization. The optimization study on the design variables was performed by GenOpt, a generic optimization program which minimizes an objective function with respect to multiple variables. This study has been carried out on different objective functions and reveals that maximizing the production of cooling energy means damaging the fresh water production. A compromise solution has been chosen to balance the contrast between cooling energy and fresh water production.
37
Telci, Ilker Tonguc. "Optimal water quality management in surface water systems and energy recovery in water distribution networks." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45861.
Full textAbstract:
Two of the most important environmental challenges in the 21st century are to protect the quality of fresh water resources and to utilize renewable energy sources to lower greenhouse gas emissions. This study contributes to the solution of the first challenge by providing methodologies for optimal design of real-time water quality monitoring systems and interpretation of data supplied by the monitoring system to identify potential pollution sources in river networks. In this study, the optimal river water quality monitoring network design aspect of the overall monitoring program is addressed by a novel methodology for the analysis of this problem. In this analysis, the locations of sampling sites are determined such that the contaminant detection time is minimized for the river network while achieving maximum reliability for the monitoring system performance. The data collected from these monitoring stations can be used to identify contamination source locations. This study suggests a methodology that utilizes a classification routine which associates the observations on a contaminant spill with one or more of the candidate spill locations in the river network. This approach consists of a training step followed by a sequential elimination of the candidate spill locations which lead to the identification of potential spill locations. In order to contribute the solution of the second environmental challenge, this study suggests utilizing available excess energy in water distribution systems by providing a methodology for optimal design of energy recovery systems. The energy recovery in water distribution systems is possible by using micro hydroelectric turbines to harvest available excess energy inevitably produced to satisfy consumer demands and to maintain adequate pressures. In this study, an optimization approach for the design of energy recovery systems in water distribution networks is proposed. This methodology is based on finding the best locations for micro hydroelectric plants in the network to recover the excess energy. Due to the unsteady nature of flow in water distribution networks, the proposed methodology also determines optimum operation schedules for the micro turbines.
38
Magagna, Davide. "Oscillating water column wave pump : a wave energy converter for water delivery." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/349009/.
Full textAbstract:
The research presented in this dissertation investigates the development and the performances of a new type of Wave Energy Converter (WEC) aimed to provide water delivery and energy storage in the form of potential energy. The Oscillating Water Column Wave Pump (OWCP) concept was proposed and tested through a series of experimental investigations supported by scientific theory. The OWCP was developed after an extensive study of the existing wave energy technology available, from which it emerged that the Oscillating Water Column (OWC) device could be further implemented for water delivery purposes. The existing theory of the OWC was employed to develop a mathematical theory able to describe the system wave response and water removal of the OWCP. In order to understand and validate the mathematical models of the OWCP, experimental investigations were carried out under the influence of incident linear waves in a two-dimensional (2D) and three-dimensional (3D) wave flume. The experimental equipment and methodology are outlined, including the description of wave flumes, models and data acquisition equipment. Experimental tests were used to verify the concept of the OWCP and assess its performances, investigating both the response of the device to the waves with and without water removal. In order to increase the efficiencies of delivery, array configurations of multiple OWCPs were adopted. The research demonstrated that up to 14% of the energy carried by the incoming waves can be converted into useful potential energy for a single device. Moreover a further increase of the efficiencies can be obtained with the array configuration improving the overall capability of the OWCP, for optimal separation distance between the array components. Further model tests are required to extended this research to validate the developed mathematical models as an effective prediction tool of the performances of the OWCP and further increase the efficiency of water removal that can be achieved.
39
Sainz, Gabriel. "The Zambezi River Basin: Water Resources Management : Energy-Food-Water nexus approach." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-159566.
Full textAbstract:
The energy-food-water nexus is of fundamental significance in the goal towards sustainable development. The Zambezi River Basin, situated in southern Africa, currently offers vast water resources for social and economic development for the eight riparian countries that constitute the watershed. Hydropower generation and agriculture are the main water users in the watershed with great potential of expansion, plus urban water supply materialise the largest consumers of this resource. Climate and social changes are pressuring natural resources availability which might show severe alterations due to enhances in the variability of precipitation patterns. This study thus examines the present water resources in the transboundary basin and executes low and high case future climate change incited scenarios in order to estimate the possible availability of water for the period 2060-2099 by performing water balances. Along with projections of water accessibility, approximations on water demands from the main consumer sectors are performed. Results show an annual positive balance for both projected scenarios due to an increase in precipitation during the wet season. They also present a severe increase in overall temperature for the region contributing to a strong increase in evapotranspiration. Projections further inform of an acute increase in water demand for irrigation and urban supply, nevertheless, evaporation from hydropower storage reservoirs continues to exceed water with drawals in volume. Acknowledging the uncertainty contained in this report allows a broader offer of recommendations to be considered when planning for future developments with a sustainable approach. Improvement of hydrological collection systems in the Zambezi basin is indispensable to accomplish a deeper and cohesive understanding of the watershed waterresources. Cooperation and knowledge communication between riparian countries seems to be the right beginning towards social and economic sustainable development for the Zambezi River Basin.
40
Jeong, Seung Hyo. "The Impact of Water-Energy Feedback on Water Conservation at Residence Halls." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23729.
Full textAbstract:
Demand for potable water and energy is increasing with growing populations and economies and many fear that scarcity of such resources will become a significant worldwide problem in the future. As such, promoting water and energy conservation in residential building environments has become an important focal area for research. Providing feedback of water or energy consumption to residential building occupants has been demonstrated to be effective in promoting water and energy conservation separately. However, although water and energy are inexorably connected, we lack research that investigates the bridge between water and energy in the representation of feedback to promote water conservation. In this paper, we describe a study that was designed to investigate the impact of two different representations of water consumption feedback on water conservation. Water consumption was represented to consumers in one of two different ways: 1) gallons and 2) gallons along with the estimated embodied energy of water consumption. The study was conducted in 18 residential halls at Virginia Tech and lasted approximately six weeks. The outcome of the study suggests that representing water consumption in terms of gallons together with the embodied energy associated with water consumption can lead to a statistically significant reduction in water conservation while representing water consumption only in terms of gallons may not. This has significant implications for future water feedback designed to promote water conservation and the study indicates that non-monetary approach can be taken.Master of Science
41
Zhu, Yiwen. "A methodology to pre-screen commercial buildings for potential energy savings using limited information." Texas A&M University, 2005. http://hdl.handle.net/1969.1/3179.
Full textAbstract:
Typical energy audits are sufficiently expensive and time-consuming that many
owners and managers of buildings are not willing to invest the time and money required
for a full audit. This dissertation provides a methodology to identify buildings with large
potential energy savings using limited information, specifically, utility bills, total area
and weather data. The methodology is developed based on the hypothesis: if a
commercial building is properly designed, constructed, operated, and maintained, the
measured energy consumption should approximately match the simulated value for a
typical building of the same size with the most efficient HVAC system; otherwise, there
may be potential for energy savings. There are four steps in the methodology: 1) testing
to determine whether the utility bills include both weather-dependent and weatherindependent
loads; 2) separating weather-dependent and weather-independent loads
when both are present in the same data; 3) determining the main type of HVAC system;
4) estimating potential energy savings and recommending an energy audit if appropriate.
The Flatness Index is selected to test whether the utility bills include both weatherdependent
and weather-independent loads. An approach to separate the utility bills based
on thermal balance is developed to separate utility bills into weather-dependent and
weather-independent loads for facilities in hot and humid climates. The average relative
error in estimated cooling consumption is only 1.1% for 40 buildings in Texas, whereas it is -54.8% using the traditional 3P method. An application of fuzzy logic is used to
identify the main type of HVAC system in buildings from their 12-month weatherdependent
energy consumption. When 40 buildings were tested, 18 systems were
identified correctly, seven were incorrect and the HVAC system type cannot be identified
in 15 cases. The estimated potential savings by the screening methodology in eight large
commercial buildings were compared with audit estimated savings for the same
buildings. The audit estimated savings are between 25% - 150% of the potential energy
savings estimated by the screening procedure in seven cases. The other two cases are less
accurate, indicating that further refinement of the method would be valuable. The data
required are easily obtained; the procedure can be carried out automatically, so no
experience is required. If the actual type of HVAC system, measured weather-dependent,
and weather-independent energy consumption are known, the methodology should work
better.
42
Kong, Chim Chan. "Project management control : a case study of the Macau Water Supply Company Limited (S.A.A.M.)." Thesis, University of Macau, 2000. http://umaclib3.umac.mo/record=b1636727.
Full text
43
Wibowo, Rulianda Purnomo. "Optimal irrigation strategy with limited water availability accounting for the risk from weather uncertainty." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/34148.
Full textAbstract:
Doctor of PhilosophyDepartment of Agricultural Economics
Nathan P. Hendricks
Risk averse farmers face a substantial challenge managing irrigation water when they face limited water availability. The two primary reasons for limited water availability in the High Plains Aquifer region of the United States are limited well capacity (i.e., the rate at which groundwater can be extracted) or a constraint imposed by a policy. In this dissertation, I study how risk averse farmers optimally manage limited water availability in the face of weather uncertainty and also the impact of limited water availability on farmer welfare. I use AquaCrop, a daily biophysical crop simulation model, to predict corn yield under alternative irrigation scenarios with historical weather. Since no simple functional form exists for the crop production function, I use discrete optimization and consider 234,256 potential irrigation strategies. I also account for risk preferences by using expected utility analysis to determine the optimal irrigation strategy. Using a daily biophysical model is important because water stress in a short period of the growing season can impact crop yield (even if average water availability throughout the growing season is sufficient) and well capacity is a constraint on daily water use. The daily biophysical crop simulation model accounts for the dynamic response of crop production to water availability. First, I examine how optimal irrigation strategies change due to limited water availability. I find that it is never optimal for irrigators to apply less than a particular minimum instantaneous rate per irrigated acre. An optimal required instantaneous rate implies that a farmer with a low well capacity focuses on adjustment at the extensive margin. On the other hand, farmers who initially have a high well capacity should adjust at the intensive margin in response to well capacity declining. I also find that total water use increases as the degree of risk aversion increases. More risk averse farmers increase water use by increasing irrigation intensity to reduce the variance in corn yields. Another important finding is that a higher well capacity could actually promote less water use because the higher well capacity allows a greater instantaneous rate of application that allows the farmer to decrease irrigation intensity while still maintaining or increasing corn yield. This finding may imply an accelerated rate of groundwater extraction when the groundwater depletion reaches a particular threshold. Second, I analyze the welfare loss due to limited water availability. The relationship between welfare loss and well capacity due to a policy constraint differs by soil type. I found the welfare loss from a water constraint policy does not always increase as well capacity increases. Farmers with very high well capacity may make small or no adjustment at the extensive margin due to a higher instantaneous rate and higher soil water holding capacity. However, that is not the case for a farmer with land that has lower soil water holding capacity as the increase in well capacity results in greater welfare loss. I also investigate the effect of risk averse behavior on the magnitude of welfare loss. I found that the welfare loss per unit of reduced water use is lower for the farmer with more risk aversion. Thus, economic models that ignore risk aversion misestimate the cost of reducing water use. Finally, I investigate the incentive for adopting drip irrigation and its effect on water use. I find that a decrease in well capacity increases the benefits of adopting drip irrigation but is not sufficient to overcome the high initial investment cost without government support. While subsidies of the magnitude offered by current U.S. programs are sufficient to induce drip irrigation adoption, I find that such subsidies have the unintended consequence of increasing total water use, particularly for small well capacities.
44
Bozzi, Federica. "Development of a configurable model for temperature distribution estimation in multifamily houses with limited amount of sensors." Thesis, KTH, Tillämpad termodynamik och kylteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-247899.
Full textAbstract:
The biggest environmental challenge of the current century is limiting the CO2 emissions in order to contrast the global warming and keep the temperature increase below 2.0K with respect to the pre-industrial age. For succeeding in this goal, significant changes are required in all sectors, including the energy one. For our society to reach the goal it is important to act not just on the production side of the energy, but also on the utilization one. In the last decades, the economic well-being drove people to a continuous search for comfort. In the building sector this behavior brought to the consumption of huge amounts of energy. Nowadays, the final target of most of the companies working in this sector is therefore to guarantee the thermal comfort desired by the inhabitants while minimizing the energy consumption. The parameter that most affects people thermal sensation is the perceived temperature. Several models have been already created with the purpose of estimating the temperature value inside a certain environment, but these are generally characterized by two main limitations. First of all the focus is on a single room or apartment and not on the building as a whole. Secondly the model is specific and cannot be applied to other structures. The purpose of the thesis is to elaborate a general model able to estimate the temperature distribution inside any Multifamily House (MFH). The reasoning behind the chosen typology is the significant share that it has in the building market. This model should be reliable enough and, at the same time, characterized by short computational time. Building this model could be the first step for being able in the future to operate a real time control on the thermal indoor conditions. While developing the model particular attention has been given to the impact of climatic conditions on the indoor temperature.The contribution of sun and wind has been considered at different levels of detail. On the basis of the calculation approach utilized for them, different configurations have been identified. Each of them, in addition, has been analyzed with and without optimization process of the space heating power distribution. The RMSE value of the different configurations has been utilized during the comparison as a measure of the model accuracy. From the analysis the best model resulted to be the not-optimized one considering the solar radiation dependent on the incidence angle and with negligible wind effect. The main strong characteristic of the model is its configurability: it can adapt to the geometry, orientation and apartments disposition of any MFH. The model has also some limitations such as the fact that it can be used just for buildings provided with mechanical ventilation and not one without such as green or passive houses. In addition, the model does neglect empty apartments and does not consider the heat and mass transfer between adjacent flats. The report has been developed as follows. The first chapter is an introduction to the thesis. The background provides insights about the actual situation regarding the temperature measurements inside a building. The addressed problem is reported together with the delimitation regarding the typology of building taken into consideration. The methodology utilized for developing the model closes the first chapter. The second one reports the state of art concerning the temperature distribution models. The third chapter contains the input data required by the model, the description of the different heat fluxes involved in it and how they are related to the building geometry and to the apartments disposition. The equation utilized for the temperature calculation is then analyzed. The chapter ends with the description of the steps for obtaining a 3D temperature visualization and with an overview on the whole process for evaluating the temperature distribution. In the chapter four are reported the results obtained with the different models and configurations. These are further analyzed, compared and discussed in the fifth chapter, in which is the best model is also identified. The thesis ends with the a glimpse on possible future work and a general conclusion about the developed model.
45
Stults, Erica Suzanne. "Minimizing Water Requirements for Electricity Generation in Water Scarce Areas." Digital WPI, 2015. https://digitalcommons.wpi.edu/etd-dissertations/265.
Full textAbstract:
Renewable energy technologies are infrequently evaluated with regard to water use for electricity generation; however traditional thermoelectric power generation uses approximately 50% of the water withdrawn in the US. To address problems of this water-energy nexus, we explore the replacement of existing electricity generation plants by renewable technologies, and the effect of this replacement on water use. Using a binary mixed integer linear programing model, we explore how the replacement of traditional thermoelectric generation with renewable solar and wind technologies can reduce future water demands for power generation. Three case study scenarios focusing on the replacement of the J.T. Deely station, a retiring coal thermoelectric generation plant in Texas, demonstrate a significant decrease in water requirements. In each case study, we replace the generation capacity of the retiring thermoelectric plant with three potential alternative technologies: solar photovoltaic (PV) panels, concentrated solar power (CSP), and horizontal axis wind turbines (HAWT). The first case study, which was performed with no limits on the land area available for new renewable energy installations, demonstrated the water savings potential of a range of different technology portfolios. Our second case study examined the replacement while constrained by finite available land area for new installations. This demonstrated the trade-off between land-use efficient technologies with water-use efficiency. Results from our third case study, which explored the replacement of a gas-fired plant with a capacity equivalent to the J. T. Deely station, demonstrated that more water efficient thermoelectric generation technologies produce lower percentages of water savings, and in two scenarios the proposed portfolios require more water than the replaced plant. Comparison of multiple aspects of our model results with those from existing models shows comparable values for land-use per unit of electricity generation and proposed plant size. An evaluation of the estimated hourly generation of our model’s proposed solution suggests the need for a trade-off between the intermittency of a technology and the required water use. As we estimate the “costs� of alternative energy, our results suggest the need to include in the expression the resulting water savings.
46
Barnett, John B. "Addressing Policy Challenges to Woody Biopower Production| Social Acceptance, Biomass Certification and Limited Policy Support." Thesis, Michigan Technological University, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10982309.
Full textAbstract:
Forestlands have been identified as a valuable resource to mitigate climate change due to the biome’s capacity to both sequester greenhouse gases and substitute for fossil fuels. Woody biomass has been proposed as a substitutable input for coal-generated electricity as economies attempt to transition to renewable power while addressing economic development goals. However, increasing the intensity of forest management for energy production has the potential to result in significant ecological, economic and social consequences at local, regional and global scales. In this context, my dissertation explores the capacity of existing policy frameworks to stimulate and support sustainable power production from forest biomaterials. In Chapter Two, I explore the interactions between shifting goals, actors and institutions in influencing incentives that shape today’s policy mix for woody biopower production in Wisconsin. The study’s results reveal that the state’s shifting focus away from using renewable energy as a means to pursue climate change mitigation and energy security goals combined with an absence of supportive coalitions has resulted in the dismantling of support for the woody biopower policy framework. In Chapter Three, I use data from a household survey of Tomahawk, Wisconsin residents to evaluate support for woody biomass production for power generation. Results show that respondents in biomass producing communities are more supportive of biomass sources such as forestry residues and forestry thinnings than dedicated harvesting operations. In addition, the results indicate that using an ecosystem services approach can help explain differences in support between these respondents and provide insights into socially acceptable forms of biomass harvesting operations. Chapter Four evaluates the use of sustainable forest management certification programs as a policy instrument to source sustainable woody biomass. The study evaluated the Forest Stewardship Council (FSC) and Sustainable Forestry Initiative (SFI) certification programs using bioenergy sustainability criteria found in the academic literature. The analysis shows a deficiency in these programs to address key criteria pertaining to climate change mitigation and would be improved by coupling sustainable forest management programs with bioenergy sustainability schemes such as designed by the Roundtable on Sustainable Biomaterials.
47
Kuo, Yenting. "Photocatalytic water splitting." Diss., Kansas State University, 2011. http://hdl.handle.net/2097/12141.
Full textAbstract:
Doctor of PhilosophyDepartment of Chemistry
Kenneth J. Klabunde
New photocatalystic materials Ti-In oxy(nitride) and nanosized Ru-loaded strontium titanate doped with Rh (Ru/SrTiO3:Rh) have been synthesized. The textural and surface characteristic properties were studied by nitrogen BET analysis, diffuse reflectance UV-vis spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy and powder XRD. The photocatalytic properties were enhanced by the binary metal oxides of titanium dioxide and indium oxide. The XRD patterns confirmed the oxygen exchange between two metal oxides during the synthesis. Moreover, the presence of titanium dioxide can help the stabilization of InN during hot NH3(g) treatment. On the other hand, the particle sizes of aerogel prepared Ru/SrTiO3:Rh varied from 12 to 25 nm depended on different Rh doping. A mixture of ethanol and toluene was found to be the best binary solvent for supercritical drying, which yielded a SrTiO3 sample with a surface area of 130 m2 Enhanced photocatalytic hydrogen production under UV-vis light irradiation was achieved by ammonolysis of intimately mixed titanium dioxide and indium oxide at high temperatures. Gas chromatography monitored steadily the formation of hydrogen when sacrificial (methanol or ethanol) were present. XRD patterns confirmed that the photocatalysts maintain crystalline integrity before and after water splitting experiments. Moreover, the presence of InN may be crucial for the increase of hydrogen production activities. /g and an average crystallite size of 6 nm. These Ru/SrTiO3:Rh photocatalysts have been studied for photocatalytic hydrogen production under visible light. The band gap of the bulk SrTiO3 (3.2 eV) does not allow response to visible light. However, after doping with rhodium and loaded with ruthenium, the modified strontium titanates can utilize light above 400 nm due to the formation of valence band or electron donor levels inside of the band gap. Moreover, the surface areas of these photocatalysts are much larger than conventional solid-state synthesized samples (1-2 m 2/g), which yielded more Ru loading and reaction sites. The areogel and hydrothermal synthesized samples required basic (alkaline) conditions for hydrogen generation facilitation compared with acidic conditions for conventional solid-state samples.
48
Mo, Weiwei. "Water's Dependence on Energy: Analysis of Embodied Energy in Water and Wastewater Systems." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4374.
Full textAbstract:
Water and wastewater treatment is a critical service provided for protecting human health and the environment. Over the past decade, increasing attention has been placed on energy consumption in water and wastewater systems for the following reasons: (1) Water and energy are two interrelated resources. The nexus between water and energy can intensify the crises of fresh water and fossil fuel shortages; (2) The demand of water/wastewater treatment services is expected to continue to increase with increasing population, economic development and land use change in the foreseeable future; and (3) There is a great potential to mitigate energy use in water and wastewater systems by recovering resources in wastewater treatment systems. As a result, the goal of this dissertation study is to assess the life cycle energy use of both water supply systems and wastewater treatment systems, explore the potential of integrated resource recovery to reduce energy consumption in wastewater systems, and understand the major factors impacting the life cycle energy use of water systems.
To achieve the goal, an input-output-based hybrid embodied energy model was developed for calculating life cycle energy in water and wastewater systems in the US. This approach is more comprehensive and less labor intensive than the traditional life cycle assessment. Additionally, this model is flexible in terms of data availability. It can give a rough estimation of embodied energy in water systems with limited data input. Given more site specific data, the model can modify the embodied energy of different energy paths involved in water related sectors.
Using the input-output-based hybrid embodied energy model, the life cycle energy of a groundwater supply system (Kalamazoo, Michigan) and a surface water supply system (Tampa, Florida) was compared. The two systems evaluated have comparable total energy embodiments based on unit water production. However, the onsite energy use of the groundwater supply system is approximately 27% greater than the surface water supply system. This was primarily due to more extensive pumping requirements. On the other hand, the groundwater system uses approximately 31% less indirect energy than the surface water system, mainly because of fewer chemicals used for treatment. The results from this and other studies were also compiled to provide a relative comparison of embodied energy for major water supply options. The comparison shows that desalination is the most energy intensive option among all the water sources. The embodied energy and benefits of reclaimed water depend on local situations and additional treatment needed to ensure treated wastewater suitable for the desired application.
A review was conducted on the current resource recovery technologies in wastewater treatment systems. It reveals that there are very limited life cycle studies on the resource recovery technologies applied in the municipal wastewater treatment systems and their integrations. Hence, a life cycle study was carried out to investigate the carbon neutrality in a state-of-art wastewater treatment plant in Tampa, FL. Three resource recovery methods were specifically investigated: onsite energy generation through combined heat and power systems, nutrient recycling through biosolids land application, and water reuse for residential irrigation. The embodied energy and the associated carbon footprint were estimated using the input-output-based hybrid embodied energy model and carbon emission factors. It was shown that the integrated resource (energy, nutrient and water) recovery has the potential to offset all the direct operational energy; however, it is not able to offset the total embodied energy of the treatment plant to achieve carbon neutrality. Among the three resource recovery methods, water reuse has the highest potential of offsetting carbon footprint, while nutrient recycling has the lowest.
A final application of the model was to study on the correlation between embodied energy in regional water supply systems and demographic and environmental characteristics. It shows that energy embodied in water supply systems in a region is related to and can be estimated by population, land use patterns, especially percentage of urban land and water source, and water sources. This model provides an alternative way to quickly estimate embodied energy of water supply in a region. The estimated embodied energy of water supply can further be used as a supporting tool for decision making and planning.
49
Hastie, Michele. "Energy and Water Conservation in Biodiesel Purification Processes." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/20384.
Full textAbstract:
Biodiesel purification processes generate wastewater streams that require a large amount of energy when distillation is used as a treatment technology. Process simulation software was used to show that an alternative water treatment process involving ion exchange would require only 31% of the energy used by distillation. Experiments showed that multiple washing stages were required to meet the standard specification for sodium, an impurity present in crude biodiesel, when washing biodiesel made from used frying oil. A comparison was made between washing biodiesel in a cross-current washing configuration and a counter-current configuration. Both configurations met the specification for sodium within three washing stages; however, the counter-current configuration required less water, making it the more efficient process. Lastly, the removal of sodium from wastewater samples using an ion exchange resin was experimentally investigated. The results validated the use of ion exchange to reduce energy consumption in biodiesel purification.
50
Cohen, R. R. "Thermal energy accumulation in stratified hot water stores." Thesis, Cranfield University, 1986. http://hdl.handle.net/1826/4195.
Full textAbstract:
Hot water thermal energy stores have the potential to improve and
extend the performance of many kinds of energy system. Waperature
stratification in the store is likely to affect the system's
efficiency. A basic but accurate computer model of the hot water
store under various inlet flow conditions is a requisite means of
assesiing promising applications of hot water storage by system
computer simulation techniques.
A microprocessor-controlled test facility has been constructed to
evaluate the performance of a 3m
3
hot water store under a wide range
of inlet flow conditions, using a temperature step input approach.
Three types of inlet/outlet ports have been examined: horizontal,
vertical and distributors. The results show that two distinct
regions evolve within the store: a fully-mixed region adjacent to
the inlet port and a region of smooth 'plug-flow' in the remaining
volume of the store. The performance of the store is shown to be
defined by the initial depth of the fully-mixed region which in turn
is seen to be closely related to the buoyancy and momentum fluxes of
the inlet flow.
The behAviour of the store and the evident correlations have enabled
a one-dimensional computer model of the store to be developed, taking
into account the turbulent mixing, vertical heat conduction and heat
losses to the surrounding areas. The model has been successfully
validated against the results from the step input experiments.
The model has been integrated into a computer simulated central
heating system which incorporates a hot water store. Predictions have
been made, using the simulation, of the energy savings which may be
achieved with the use of storage in comparison to a conventional
system, and an assessment has been made of the economic viability of
the application.