Dissertations / Theses on the topic 'Energy engineering'

Using energy more efficiently is essential if carbon emissions are to be reduced. According to the International Energy Agency (IEA), energy efficiency improvements represent the largest and least costly savings in carbon emissions, even when compared with renewables, nuclear power and carbon capture and storage. Yet, how should future priorities be directed? Should efforts be focused on light bulbs or diesel engines, insulating houses or improving coal-fired power stations? Previous attempts to assess energy efficiency options provide a useful snapshot for directing short-term responses, but are limited to only known technologies developed under current economic conditions. Tomorrow's economic drivers are not easy to forecast, and new technical solutions often present in a disruptive manner. Fortunately, the theoretical and practical efficiency limits do not vary with time, allowingthe uncertainty of economic forecasts to be avoided and the potential of yet to be discovered efficient designs to be captured. This research aims to provide a rational basis for assessing all future developments in energy efficiency. The global fow of energy through technical devices is traced from fuels to final services, and presented as an energy map to convey visually the scale of energy use. An important distinction is made between conversion devices, which upgrade energy into more useable forms, and passive systems, from which energy is lost as low temperature heat, in exchange for final services. Theoretical efficiency limits are calculated for conversion devices using exergy analysis, and show a 89% potential reduction in energy use. Efforts should befocused on improving the efficiency of, in relative order: biomass burners, refrigeration systems, gas burners and petrol engines. For passive systems, practical utilisation limits are calculated based on engineering models, and demonstrate energy savings of 73% are achievable. Significant gains are found in technical solutions that increase the thermal insulation of building fabrics and reduce the mass of vehicles. The result of this work is a consistent basis for comparing efficiency options, that can enable future technical research and energy policy tobe directed towards the actions that will make the most difference.

This thesis examines the fundamental equations of the branch of linear oscillatory dynamics known as Statistical Energy Analysis (SEA). The investigation described is limited to the study of two, point coupled multi-modal sub-systems which form the basis for most of the accepted theory in this field. Particular attention is paid to the development of exact classical solutions against which simplified approaches can be compared. These comparisons reveal deficiencies in the usual formulations of SEA in three areas, viz., for heavy damping, strong coupling between sub-systems and for systems with non-uniform natural frequency distributions. These areas are studied using axially vibrating rod models which clarify much of the analysis without significant loss of generality. The principal example studied is based on part of the structure of a modem warship. It illustrates the simplifications inherent in the models adopted here but also reveals the improvements that can be made over traditional SEA techniques. The problem of heavy damping is partially overcome by adopting revised equations for the various loss factors used in SEA. These are shown to be valid provided that the damping remains proportional so that inter-modal coupling is not induced by the damping mechanism. Strong coupling is catered for by the use of a correction factor based on the limiting case of infinite coupling strength, for which classical solutions may be obtained. This correction factor is used in conjunction with a new, theoretically based measure of the transition between weakly and strongly coupled behaviour. Finally, to explore the effects of non-uniform natural frequency distributions, systems with geometrically periodic and near-periodic parameters are studied. This important class of structures are common in engineering design and do not posses the uniform modal statistics commonly assumed in SEA. The theory of periodic structures is used in this area to derive more sophisticated statistical models that overcome some of these limitations.

This report aims to evaluate if and how a microgrid could be constructed on AirSon Engineering AB:s estate. The main focus of the report is legislation, benefits with energy storage, different energy storage systems, system control and energy and power balances. A literature study and processing of data are used to answer the reports questions. The goal with this study is that the microgrid can be constructed without the need of concession. If certain exceptions are met Swedish legislation approves construction of a microgrid without concession. Additionally, the microgrid needs to fulfill the law about micro producers to get tax reduction. If possible, the current through the main fuse will not exceed 63 amperes. By reducing the production, the current can be limited to 63 amperes. Further, three energy storage systems are evaluated, lithium-ion battery, nickel metal hydride battery and hydrogen fuel cell. Lithium-ion battery is best suited when it comes to performance. From an economic perspective the size of the energy storage and charging cycles determines which system that is preferable. Variations in electricity price from night to morning gives an economic benefit from an energy storage via buying electricity night-time and using it in the morning. Furthermore, the energy storage leads to higher self-sufficiency and self-utilization. The microgrid will consist of 104,7 kilowatt peak power solar power and 3 kilowatt wind power. By collecting data from the estate and weather data from PVGIS energy and power balances are calculated. The microgrid will be a direct current grid and will be controlled by a so called EnergyHub, which is a product from Ferroamp that also balances the phases. Moreover, self-sufficiency and self-utilization are used to determine the optimal size of the energy storage system. A larger energy storage system will conclude in higher self-sufficiency and self-utilization. However, the self-sufficiency increases exceedingly little in compared to the increasement of the energy storage size.

This doctoral study discusses how to control fluctuating renewable energy sources at converter, unit, and system layers to deliver smoothed power output to the grid. This is particularly relevant to renewable power generation since the output power of many kinds of renewable energy sources have huge fluctuations (e.g. solar, wind and wave) that needs to be properly treated for grid integration. In this research, the energy quality is developed to describe the friendliness and compatibility of power flows/waveforms to the grid, by contrast with the well-known concept of power quality which is used to assess the voltage and current waveforms. In Chapter 1 & 2, a background introduction and a literature review of studied subjects are presented, respectively. In Chapter 3, the problem of determining the PI parameters in dq decoupling control of voltage source converter (VSC) is studied based on a state-space model. The problems of the conventional method when there is insufficient interface resistance are addressed. New methods are proposed to overcome these drawbacks. In Chapter 4 & 5, energy quality and the energy filters (EFs) are proposed as tools to assess and manage power fluctuations of renewable energy sources. The proposed EFs are energy storage control systems that could be implemented on a variety of energy storage hardware. EFs behave like low-pass filters to the power flows. Finally, in Chapter 6, as an application example of renewable power plant with energy filter control and smoothed power output, a master-slave wave farm system is proposed. The wave farm system uses enlarged rotor inertia of electric machines as self-energy storage devices.

This thesis investigated the use cases of Electric Vehicles (EV) and stationary battery storage in a multi-level energy system with high penetration of renewable DER. The different energy system levels considered include large and local level, distribution network and customer premises. The reduction of excess electricity due to high shares of renewable energy technologies by using EV with Vehicle to Grid capability in a future GB energy system was investigated. It was found that with EV in vehicle to grid mode integrated into the energy system, the utilisation of fluctuating wind power was increased. This was realised by minimising the curtailment of excess electricity and CO2 emissions. Also in a local energy system with a high share of intermittent renewable energy, EV with Vehicle to Grid capability can reduce electricity import of about 34%. A microgrid was modelled for evaluating the impact of electrical vehicle charging on voltage profiles and energy losses in a local distribution network with a high share of distributed energy resources. The results show that with a smart charging scheme, the voltage profiles remain within distribution network operator’s defined limit. A reduction of energy losses in the microgrid was also noted. An optimisation tool using an optimisation technique was developed for optimising charging and discharging of a stationary battery storage. This was simulated to evaluate the revenue streams for an existing photovoltaic generation system. The key benefit of the photovoltaic generation system to the owner is the ability to maximise feed in tariff revenue streams by maximising self-consumption using a wholesale electricity tariff. The impact of storage unit cost on the adoption of battery storage for the photovoltaic generation system was also simulated using a time of use tariff. It was found that battery storage for the simulated system will only be economically viable when battery unit cost drops to £138/kWh. The impact of an optimised distributed energy system simulated in the Lawrence Berkeley’s Distributed Energy Resources Customer Adoption Model (DER-CAM) on distribution network constraints was investigated using a soft-linking power flow simulation procedure. It was found that voltage excursions occur mostly during peak day-types. It was found out that not all optimised distributed energy systems are feasible from the distribution network’s point of view.

Ubiquitous computing and pervasive networks are prevailing to impact almost every part of our daily lives. Convergence of technologies has allowed electronic devices to become untethered. Cutting of the power-cord and communications link has provided many benefits, mobility and convenience being the most advantageous, however, an important but lagging technology in this vision is the power source. The trend in power density of batteries has not tracked the advancements in electronic systems development. This has provided opportunity for a bridging technology which uses a more integrated approach with the power source to emerge, where a device has an onboard self sustaining energy supply. This approach promises to close the gap between the increased miniaturisation of electronics systems and the physically constrained battery technology by tapping into the ambient energy available in the surrounding location of an application. Energy harvesting allows some of the costly maintenance and environmentally damaging issues of battery powered systems to be reduced. This work considers the characteristics and energy requirements of wireless sensor and actuator networks. It outlines a range of sources from which the energy can be extracted and then considers the conversion methods which could be employed in such schemes. This research looks at the methods and techniques for harvesting/scavenging energy from ambient sources, in particular from the motion of human traffic on raised flooring and stairwells for the purpose of powering wireless sensor and actuator networks. Mechanisms for the conversion of mechanical energy to electrical energy are evaluated for their benefits in footfall harvesting, from which, two conversion mechanisms are chosen for prototyping. The thesis presents two stair-mounted generator designs. Conversion that extends the intermittent pulses of energy in footfall is shown to be the beneficial. A flyback generator is designed which converts the linear motion of footfall to rotational torque is presented. Secondly, a cantilever design which converts the linear motion to vibration is shown. Both designs are mathematically modelled and the behaviour validated with experimental results & analysis. Power, energy and efficiency characteristics for both mechanisms are compared. Cost of manufacture and reliability are also discussed.

One of the legacies of the apartheid policies in South Africa has been·the huge gap between rich and poor households in terms of their access to basic energy services. This study explores the essence of shifting from· supply-driven approach to an integrated framework in energy planning order to evolve policies that match national goals and objectives with the energy needs of the low-income households. The principles of Integrated Energy Planning (IEP) are outline for the household sector and the development of an energy database is identified as one of the important processes required in IEP. The design of the database is practically demonstrated by capturing existing secondary and primary data on energy use in low-income households in South Africa. The user-interface and on-line data analysis of the database are also illustrated. Furthermore, the data has been extensively analysed to show the factors that influence energy demand in the low-income households and how these factors may interact with one another. In·addition, energy grid-use data·has been aggregated from the· database as input into an energy modelling computer programme for estimating energy demand projections for low-income households. These energy demand projections are based on 'energy scenarios which investigate alternate energy supply options. Thus the study illustrates how energy use data can be organised into a tool for informing policy formulation. Bibliography: p. 154-156.

The main objective of this thesis focuses on compositional design and engineering colloidal NPs and their application in energy conversion. This principally included the synthesis and characterization of colloidal NPs, and in-depth exploration of their catalytic properties. Special focus is the synthesis and characterization of copper-based chalcogenides, bimetallic and multicompent metal oxide NPs. The results were shown in the series of articles which have been published or are under review in high impact peer-review journals. These works can be extracted to conclusions as following: (1) Copper-based chalcogenides NPs: Detailed synthetic routes to produce CZTS and CZTS-based HNPs i.e. CZTS-Au, CZTS-Pt and CZTS-Ag2S. The composition, size and shape control of CZTS NCs have been achieved by tuning the precursor concentration, surfactants, gas bubbling and heating ramp. This synthetic strategy method can be easy to scale up to grams at the same time keeping above 90% yield per batch by a simple vacuum free heating-up method. We used CZTS NCs as electrocatalysts with controlled crystal phases for the ORR measurements. First-principles calculations and experiments both indicated the kesterite CZTS NCs exhibit improving electrocatalytic activities toward ORR. In additional, monodisperse CZTS-Au and CZTS-Pt HNPs were obtained base on CZTS as seeds by seed-mediated growth method. Various characterizations confirm the structure of noble-semiconductors HNPs. Such HNPs were investigated on photocatalytic degradation of dye and hydrogen evolution reaction in water, exhibited high catalytic active. The research of CZTS-based HNPs is extended to a detailed synthesis of CZTS-Ag2S HNPs involving cation exchange reaction. The structure and composition of CZTS-Ag2S could be tuned by control the ration of Ag precursors and CZTS seeds. When employing CZTS-Ag2S as sensitizers apply photoelectrochemical cell for water splitting, showed improved photocurrent response under visible-light illumination. (2) Bimetallic NPs: The synthesized Pd2Sn NPs were successfully used solution-based strategy. A mechanism of morphology structure was discussed detail based different ratio of OLA, chlorine and TOP precursors. When evaluating catalytic properties of geometry of Pd2Sn NPs, reduction of nitrophenol, water denitration and EOR were measured resulting in Pd2Sn NRs had outperformance catalytic active over Pd2Sn spherical NPs, while Pd2Sn alloy NPs exhibited better catalytic performance compare to Pd NPs. The formation of novel Au-Pd2Sn heterostructured NRs was described in detail as well. Au-Pd2Sn heterostructured NRs were synthesized via a seed-mediated growth method, which Au domains were selected to grow on the Pd2Sn seeds. The result establishes a new strategy for the development of multifunctional nanomaterials. (3) Multicompent metal oxide NPs: Mn3O4@CoMn2O4 core-shell and Mn3O4@CoMn2O4-CoO HNPs were prepared via partial cation exchange reaction via Mn3O4 seeds NPs and different cobalt precursors, which playing a crucial role whether additional nucleation of a CoO phase depending on the coordination ability of cobalt precursors. The lower coordination ability of cobalt perchlorate had a higher reactivity to grow CoO phase on Mn3O4@CoMn2O4 to form Mn3O4@CoMn2O4-CoO HNPs. In particular, such HNPs showed a superior catalytic activity and stability over the core shell catalysts and state-of-the-art electrocatalysts for ORR and OER in alkaline solution. Based on this colloidal synthetic route, Fe3O4@NixFe3-xO4 core shell NPs was obtained involving nickel perchlorate precursors to Fe3O4 seeds solution. The fabrication of this core shell NPs and ITO glass to form thin film as water oxidation catalyst exhibited an improved catalytic activity. This colloidal synthetic route offers an easy scale-up, low temperature and ambient pressure protocol to design earth-abundant, cost-effective and high activity water oxidation catalysts.
El objetivo principal de esta tesis se centra en el diseño de ingeniería de composición y NP coloidal y su aplicación en la conversión y almacenamiento de energía. Esto incluye principalmente la síntesis y caracterización de los NP coloidales, y la exploración a fondo de sus propiedades catalíticas. Se prestará especial atención es la síntesis y caracterización de calcogenuros a base de cobre, óxido de metal NP bimetálicas y multicompent. Estos trabajos se pueden extraer con el resumen de la siguiente manera: (1) calcogenuros base de cobre NP: basados ​​en CZTS rutas sintéticas detalladas para producir CZTS y heterostructured NP es decir CZTS-Au, Pt y CZTS-CZTS-Ag2S. La composición, el tamaño y la forma de control de CZTS CN se han conseguido mediante la regulación de la concentración de precursor, tensioactivos, burbujeo de gas y rampa de calentamiento. Utilizamos CZTS CN como electrocatalizadores con fases de cristal controlados para las mediciones de la reacción de reducción de oxígeno con cálculos y experimentos de primeros principios. En CZTS-Au adicionales, monodispersas, CZTS-PT y CZTS-Ag2S hetero-NP se obtuvieron sobre la base CZTS como semillas por el método de crecimiento de la semilla mediada. Tal Hetero-NP se investigaron sobre la degradación fotocatalítica de tinte, reacción de desprendimiento de hidrógeno en agua y celular fotoelectroquímico para la disociación del agua, exhibido alta catalítica activa. (2) bimetálica NP: Los Pd2Sn NP sintetizados se utilizan con éxito la estrategia basada en la solución. Un mecanismo de la estructura de la morfología se discutió detalle. Al evaluar las propiedades catalíticas de la geometría de Pd2Sn NP, la reducción de nitrofenol, desnitrificación del agua y la reacción de oxidación del etanol resultante se midieron en Pd2Sn NR había de resultados superiores activa catalítica sobre Pd2Sn esférica y Pd NP. La formación de la novela Au-Pd2Sn heterostructured NR se sintetizaron mediante un método de crecimiento de la semilla mediada, que fueron seleccionados Au dominios de crecer en las semillas de Pd2Sn. El resultado establece una nueva estrategia para el desarrollo de nanomateriales multifuncionales. (3) NP de óxido metálico Multicompent: Mn3O4@CoMn2O4 core-shell y Mn3O4@CoMn2O4-CoO hetero-NP se prepararon mediante la reacción de intercambio catiónico parcial a través de Mn3O4 semillas NP y diferentes precursores de cobalto. Tal Hetero-NP mostró una actividad catalítica y estabilidad superiores en los catalizadores de núcleo y corteza y electrocatalizadores el estado de la técnica para el oxígeno reacción de reducción / evolución en solución alcalina. En base a esta vía de síntesis coloidal, Fe3O4@NixFe3-xO4 de núcleo y corteza NP se obtuvo con precursores de perclorato de níquel a una solución semillas Fe3O4. La fabricación de este núcleo NP cáscara y el vidrio ITO para formar la película delgada como catalizador de oxidación en agua exhibe una actividad catalítica mejorada.

Advances in processor design have delivered performance improvements for decades. As physical limits are reached, however, refinements to the same basic technologies are beginning to yield diminishing returns. Unsustainable increases in energy consumption are forcing hardware manufacturers to prioritise energy efficiency in their designs. Research suggests that software modifications will be needed to exploit the resulting improvements in current and future hardware. New tools are required to capitalise on this new class of optimisation. This thesis investigates the field of energy-aware performance engineering. It begins by examining the current state of the art, which is characterised by ad-hoc techniques and a lack of standardised metrics. Work in this thesis addresses these deficiencies and lays stable foundations for others to build on. The first contribution made includes a set of criteria which define the properties that energy-aware optimisation metrics should exhibit. These criteria show that current metrics cannot meaningfully assess the utility of code or correctly guide its optimisation. New metrics are proposed to address these issues, and theoretical and empirical proofs of their advantages are given. This thesis then presents the Power Optimised Software Envelope (POSE) model, which allows developers to assess whether power optimisation is worth pursuing for their applications. POSE is used to study the optimisation characteristics of codes from the Mantevo mini-application suite running on a Haswell-based cluster. The results obtained show that of these codes TeaLeaf has the most scope for power optimisation while PathFinder has the least. Finally, POSE modelling techniques are extended to evaluate the system-wide scope for energy-aware performance optimisation. System Summary POSE allows developers to assess the scope a system has for energy-aware software optimisation independent of the code being run.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 135-146).
This thesis focuses on the understanding and engineering of a molecule known as azobenzene which holds unique properties for thermal storage applications. The azobenzene molecule undergoes structural change into a metastable state which has the ability to store energy. This thesis utilizes the energy storage and structural change properties of this molecule to develop new materials for thermal energy storage. The first is through a concept called solar thermal fuel which is storing the solar energy in rearranged bonds of the azobenzene and later releasing that energy in the form of heat. The second approach is through the structural property difference of its two states in order to moderate the phase change temperature of organic phase change materials. Essentially, the molecule azobenzene was modified and engineered to be used as a thermal battery as well as to mediate thermal energy storage in other materials. The first chapter will give a brief introduction on the concept and past examples of solar thermal fuel. Chapter 2, 3, 4 will discuss about the development of solar thermal fuel while chapter 5 discusses about a recently developed concept of using azobenzene to moderate phase change temperature. Chapter 2 shows the first demonstration of using solar thermal fuel in the solid state through functionalizing azobenzene on a polymer template. The polymer platform allows fabrication of a thin film of this material which enabled charging, discharging, and heat release using optically chargeable molecules all within the solid-state. A demonstration of solid state application was shown by constructing a macroscopic device which resulted in heat release bringing a temperature increase of as high as 10 OC. Next in chapter 3, azobenzene was engineered on the molecular lever with bulky aromatic groups (phenyl, biphenyl, and tert-butyl phenyl groups). The molecules were designed and synthesized for the purpose of increasing energy stored while promoting solid state solar thermal fuels. The design allowed fabrication of molecular based thin film, which was able to be charged with light, a great improvement from the original azobenzene, which crystallized preventing switching in the solid state. Molecular engineering proved to be a powerful and effective method in improving other solar thermal fuel properties, such as energy storage in STFs, chargeability, and also the thermal stability of the molecular thin film. In chapter 4, new diacetylene derivatives with azobenzene moieties and with varied alkyl spacers and linkers were synthesized to show photocontrolled self-assembly and disassembly of photon energy storage materials. This azobenzene decorated diacetylenes not only allowed solar energy storage but also demonstrated phase change characteristic of organic materials can be a parameter to consider in terms of designing high energy density photon energy storage materials. Chapter 5 discusses azobenzene based dopants in organic phase change material to photomoderate the phase change temperature. Three different types, 8 in total, organic phase change materials were tested to show the possibilty of this concept in a wide variety of phase change materials. A deep understanding was developed giving parameters to achieve a large phase change temperature difference in the organic phase change materials using the structual difference of the trans and the cis state of azobenzene.
by Eugene N. Cho.
Ph. D.

Ce travail a pour but d'améliorer l'efficacité énergétique des réseaux de cœur en éteignant un sous-ensemble de liens par une approche SDN (Software Defined Network). Nous nous différencions des nombreux travaux de ce domaine par une réactivité accrue aux variations des conditions réseaux. Cela a été rendu possible grâce à une complexité calculatoire réduite et une attention particulière au surcoût induit par les échanges de données. Pour valider les solutions proposées, nous les avons testées sur une plateforme spécialement construite à cet effet.Dans la première partie de cette thèse, nous présentons l'architecture logicielle ``SegmenT Routing based Energy Efficient Traffic Engineering'' (STREETE). Le cœur de la solution repose sur un re-routage dynamique du trafic en fonction de la charge du réseau dans le but d'éteindre certains liens peu utilisés. Cette solution utilise des algorithmes de graphes dynamiques pour réduire la complexité calculatoire et atteindre des temps de calcul de l'ordre des millisecondes sur un réseau de 50 nœuds. Nos solutions ont aussi été validées sur une plateforme de test comprenant le contrôleur SDN ONOS et des commutateurs OpenFlow. Nous comparons nos algorithmes aux solutions optimales obtenues grâce à des techniques de programmation linéaires en nombres entiers et montrons que le nombre de liens allumés peut être efficacement réduit pour diminuer la consommation électrique tout en évitant de surcharger le réseau.Dans la deuxième partie de cette thèse, nous cherchons à améliorer la performance de STREETE dans le cas d’une forte charge, qui ne peut pas être écoulée par le réseau si des algorithmes de routages à plus courts chemins sont utilisés. Nous analysons des méthodes d'équilibrage de charge pour obtenir un placement presque optimal des flux dans le réseau.Dans la dernière partie, nous évaluons la combinaison des deux techniques proposées précédemment : STREETE avec équilibrage de charge. Ensuite, nous utilisons notre plateforme de test pour analyser l'impact de re-routages fréquents sur les flux TCP. Cela nous permet de donner des indications sur des améliorations à prendre en compte afin d'éviter des instabilités causées par des basculements incontrôlés des flux réseau entre des chemins alternatifs. Nous croyons à l'importance de fournir des résultats reproductibles à la communauté scientifique. Ainsi, une grande partie des résultats présentés dans cette thèse peuvent être facilement reproduits à l'aide des instructions et logiciels fournis
This work seeks to improve the energy efficiency of backbone networks by automatically managing the paths of network flows to reduce the over-provisioning. Compared to numerous works in this field, we stand out by focusing on low computational complexity and smooth deployment of the proposed solution in the context of Software Defined Networks (SDN). To ensure that we meet these requirements, we validate the proposed solutions on a network testbed built for this purpose. Moreover, we believe that it is indispensable for the research community in computer science to improve the reproducibility of experiments. Thus, one can reproduce most of the results presented in this thesis by following a couple of simple steps. In the first part of this thesis, we present a framework for putting links and line cards into sleep mode during off-peak periods and rapidly bringing them back on when more network capacity is needed. The solution, which we term ``SegmenT Routing based Energy Efficient Traffic Engineering'' (STREETE), was implemented using state-of-art dynamic graph algorithms. STREETE achieves execution times of tens of milliseconds on a 50-node network. The approach was also validated on a testbed using the ONOS SDN controller along with OpenFlow switches. We compared our algorithm against optimal solutions obtained via a Mixed Integer Linear Programming (MILP) model to demonstrate that it can effectively prevent network congestion, avoid turning-on unneeded links, and provide excellent energy-efficiency. The second part of this thesis studies solutions for maximizing the utilization of existing components to extend the STREETE framework to workloads that are not very well handled by its original form. This includes the high network loads that cannot be routed through the network without a fine-grained management of the flows. In this part, we diverge from the shortest path routing, which is traditionally used in computer networks, and perform a particular load balancing of the network flows. In the last part of this thesis, we combine STREETE with the proposed load balancing technique and evaluate the performance of this combination both regarding turned-off links and in its ability to keep the network out of congestion. After that, we use our network testbed to evaluate the impact of our solutions on the TCP flows and provide an intuition about the additional constraints that must be considered to avoid instabilities due to traffic oscillations between multiple paths

Electron transfer (EleT) and energy transfer (EngT) are common fundamental processes in life, and increasingly in materials engineering. Proteins involved in several life-critical processes including reaction centers in photosynthesis and photolyases in DNA repair have evolved protein matrixes with sophisticated temporal and spatial control of EleT and EngT. The ability to rationally design a protein matrix for EleT and/or EngT has not yet been fully realized, but would yield many benefits across bioenergetics, bioelectronics and biomedical engineering.

Pseudomonas aeruginosa azurin has been an important model system for investigating fundamental EleT in proteins. Early pioneering studies used ruthenium photosensitizers to induce EleT in azurin and this experimental data continues to be used to develop theories for EleT mediated through a protein matrix. In this dissertation it is shown that putative EleT rates in the P. aeruginosa azurin model system, measured via photoinduced methods, can also be explained by an alternate EngT mechanism. Investigation of EngT in azurin, conducted in this study, isolates and resolves confounding phenomena—i.e., zinc contamination and excited state emission—that can lead to erroneous kinetic assignments. Extensive metal analysis, in addition to electrochemical and photochemical (photoinduced transfer) measurements suggests Zn-metallated azurin contamination can result in a biexponential reaction, which can be mistaken for EleT. Namely, upon photoinduction, the observed slow phase is exclusively the contribution from Zn-metallated azurin, not EleT; whereas, the fast phase is the result of EngT between the photosensitizer and the Cu-site, rather than simple excited state decay of the phototrigger.

In order to circumvent the previously described problems with photoinduced measurements of EleT an orthogonal glassy carbon electrode based protein film voltammetry method was developed for measuring EleT rates in azurin. Finally, Computational Protein Design was utilized to modulate intramolecular EleT and EngT rates by engineering the residue composition in the core of azurin without perturbing the donor and acceptor sites.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2016.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 207-235).
Lead sulfide colloidal quantum dots (PbS QDs) possess a uniquely tunable set of electronic properties that has generated considerable interest in their use as active materials in lightweight, flexible, solution-processed photovoltaics. The bandgap of PbS QDs can be tuned across the entire range relevant for solar cells through modification of the QD size, and a range of other QD electronic properties can be modified through control of the chemical ligands bound to the QD surface. In this thesis we demonstrate how control of the energy level profile within PbS QD solar cells can be used to understand and improve their operation. First, we demonstrate that improvements in power conversion efficiency may be attained for ZnO / PbS QD heterojunction photovoltaics through the incorporation of a MoO3 interlayer between the PbS QD film and the top-contact anode. The deep-work-function MoO3 layer mitigates a Schottky junction that would otherwise form at the PbS / anode interface, resulting in performance improvements for devices employing a range of different anode materials. Then, we demonstrate how the tunable bandgap of PbS QDs can be used to elucidate charge- and exciton-transfer processes within hybrid organic /QD photovoltaic devices that demonstrate singlet exciton fission. We find that PbS QDs can accept electrons from triplets generated by singlet fission in pentacene and act as low-bandgap light absorbers complementary to the singlet fission material, and we explore the dependence of the triplet dissociation process on the energy levels of the QDs. Finally, we show that the energy levels of lead sulfide QDs, measured by ultraviolet photoelectron spectroscopy, shift by up to 0.9 eV between different chemical ligand treatments. The directions of these energy shifts match the results of density functional theory calculations and scale with the ligand dipole moment, and trends in the performance of photovoltaic devices employing ligand-modified QD films are consistent with the measured energy level shifts. These studies identify energy level shifts resulting from interface modification, QD bandgap modification through size control, and ligand-induced surface dipoles as means of predictably controlling the electronic properties of colloidal QD films and as versatile adjustable parameters in the performance optimization of QD optoelectronic devices.
by Patrick Richard Brown.
Ph. D.

The large-scale wind energy industry is relatively new and is rapidly expanding. The ability of a wind turbine to extract power from the wind is a function of three main factors: the measured wind speed, the power curve of the turbine, and the ability of the machine to handle wind fluctuations. The key parameter determining wind turbine performance is wind speed and it is normally measured with an anemometer placed at the nacelle of a turbine. The dynamic nature of wind speed, however, is a barrier for applying predictive engineering in wind energy. Traditional approaches based on physical science and mathematical modelings have limitations on wind power prediction models. Conventional approach based on dynamic modeling has disadvantage of power generation process modeling due to time-shift nature of the process. Data mining is a promising approach for modeling wind energy, e.g., power prediction and optimization, wind speed forecasting, power curve monitoring and fault diagnosis. It involves a number of steps including data pre-processing, data sampling, feature selection, dimension reduction and, etc. This thesis focus on applying data mining to predictive engineering in wind industry, and ultimately builds wind speed prediction and wind farm power prediction models, develops turbine dynamic control and power optimization strategy, explores methodology for system level fault diagnosis. However the philosophy, methods and frameworks discussed in this research can also be applied to other industrial processes. This thesis proposes a series of predictive models under the framework of data mining. Chapter 2 introduces a methodology for short term wind speed prediction based on wind farm layout information. Chapter 3 and Chapter 4 present prediction models for wind turbine parameters. Chapter 5 proposes strategies for dynamic control of wind turbines. Chapter 6 explores the fault diagnosis and prediction using SCADA data.

Role of nanotechnology and nanomaterials for utilization, storage and generation of hydrogen energy, generation of environment friendly thermoelectric power, generation of geothermal energy and photovoltaic or solar energy has been explored. Graphene nanosheet has emerged as a promising material for Platinum catalyst support of fuel cell to enhance electrochemically active surface area and power generation. Graphene and graphene based nanocomposites namely graphene-Polyaniline (PANI) are explored as promising alternatives for hydrogen storage. Inorganic-organic nanocomposite electrolyte membranes comprising of nanosize inorganic building block offers higher proton conductivity, ion exchange capacity and enhanced power generation when applied in a fuel cell. Nanostructured thermoelectric material enhances the power factor and figure of merit. Inorganic (bismuth telluride) –organic (conducting polymer) nanocomposites are explored as a new class of thermoelectric material. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35285

The use of satellite altimeter data for spatial mapping of the wave resource is examined. A new algorithm for estimating wave period from altimeter data is developed and validated, which enables estimates of wave energy converter (WEC) power to be derived. Maps of the long-term mean WEC power from altimeter data are of a higher spatial resolution than is available from global wave model data. They can be used for identifying promising wave energy locations along particular stretches of coastline, before a detailed study using nearshore models is undertaken. The accuracy of estimates of WEC power from wave model data is considered. Without calibration estimates of the mean WEC power from model data can be biased of the order of 10-20%. The calibration of wave model data is complicated by non-linear dependence of model parameters on multiple factors, and seasonal and interannual changes in biases. After calibration the accuracy in the estimate of the historic power production at a site is of the order of 5%, but the changing biases make it difficult to specify the accuracy more precisely. The accuracy of predictions of the future energy yield from a WEC is limited by the accuracy of the historic data and the variability in the resource. The variability in 5, 10 and 20 year mean power levels is studied for an area in the north of Scotland, and shown to be greater than if annual power anomalies were uncorrelated noise. The sensitivity of WEC power production to climate change is also examined, and it is shown that the change in wave climate over the life time of a wave farm is likely to be small in comparison to the natural level of variability. It is shown that despite the uncertainty related to variability in the wave climate, improvements in the accuracy of historic data will improve the accuracy of predictions of future WEC yield. The topic of extreme wave analysis is also considered. A comparison of estimators for the generalised Pareto distribution (GPD) is presented. It is recommended that the Likelihood-Moment estimator should be used in preference to other estimators for the GPD. The use of seasonal models for extremes is also considered. In contrast to assertions made in previous studies, it is demonstrated that non-seasonal models have a lower bias and variance than models which analyse the data in separate seasons.

This thesis proposes a methodology for planning, scheduling and on-line control of an energy storage system for the integration of wind energy. Using the case study of a remote wind-diesel system, the different time frames of the design and implementation process are detailed. First, a long-term planning approach for rating of the power and energy capacities of the ESS is presented, based on stochastic optimization. The formulation is then adapted into a hourly scheduling approach and results are compared with the expected cost of energy and energy requirements resulting from the planning study. The optimization results are used as training data for an artificial neural network, in an effort to generate an on-line control that captures inherent rules, using artificial intelligence. The ESS is realized as a two-level ESS and a general control structure for on-line operation of multi-level ESS is proposed and adapted for the wind-diesel system, as the first level in a hierarchical control. The system is evaluated in simulation and selected results are validated using a hardware-in-the-loop representation of the system, demonstrating that the proposed controller is realizable.
Cette thèse propose une méthodologie pour la planification, l'utilisation et la commande d'un système de stockage d'énergie permettant l'intégration de l'énergie éolienne. Utilisant comme étude de cas un réseau autonome alimenté par un système éolien-diesel, les différentes étapes de la conception et la mise en oeuvre sont détaillées. Premièrement, une étude de planification à long terme pour le dimensionnement de la puissance nominale et de la capacité énergétique du stockage est présentée, basée sur les méthodes d'optimisation stochastique. La formulation est ensuite adaptée à une commande sur une base horaire et les résultats sont comparés, au niveau de l'énergie et de la quantité d'énergie utilisée, aux résultats obtenus dans l'étude de planification. Les résultats obtenus par optimisation du système sont utilisés dans l'entrainement d'un réseau de neurones artificiels, afin de produire une commande qui capte les règles inhérentes au système, utilisant l'intelligence artificielle. Le stockage d'énergie est réalisé par un système de stockage à deux niveaux et une structure de commande appropriée à plusieurs niveaux est proposée et adaptée pour un système éolien-diesel, comme premier niveau d'une commande hiérarchique. La performance du système est évaluée par simulation et certains résultats ont été validés avec un banc d'essai. Celui-ci consiste à des convertisseurs électroniques intégrés avec une représentation par simulation temps réel du système. Les résultats obtenus concordent avec les résultats de simulation et confirment que la commande proposée est réalisable.

This thesis is about Photovoltaic (PV) cells and its stresses in various directions by calculating the power generated using solar cells under different conditions to improve its efficiency. Our research studies found that using multi-junction cells with larger substrates can increase the efficiency to some extent which in practice is limited to 43 percent. The experiment was conducted using ten solar cells each with an area of 20.9〖cm〗 ^2, where each cell gives 0.5 V and 0.4 A and a 1.25 Ω resistor was used. The cells were connected in series. Once, the PV cells were fixed horizontally and the other time tested in tilted position under same outdoor condition. The purpose of testing PV cells was to investigate the efficiency under above mentioned conditions. The data collected from the readings was used in calculation, and we have obtained from the calculations that horizontally fixed cells gave 4.8 percent efficiency whereas tilted cells gave 6.6 percent efficiency. Hence, the ratio showed that fixed cells produced 37.5 percent more power compared to horizontally fixed cells. Our other experiment consisted of testing PV cells under different temperature conditions that was done using a freezer and an oven for temperature variation and a tungsten bulb was used as a light source. The purpose of performing this experiment was to investigate how the efficiency of PV cells is affected under extreme conditions. Part of our thesis was also including studies and analysis of produced energy by the solar panel installed on the roof of “BTH” building in Karlskrona, Sweden. The data consisted of energy produced from February up to August 2014. The investigation also included finding the highest produced energy during these months. We have found that the highest energy was generated on the 1st of July which was 12.86 kWh. Furthermore, we went deep into investigation of the 1st of July to know exactly which hour of that day the highest energy was produced. The data showed that the highest produced energy was at 12:19 and 13:19 which was 2.03 kWh.
Ramzi: +46723231353, +966561993488 Zain:

The underlying idea of this thesis is that the surface chemical and morphological nature of bacterial strains uniquely differentiates one from another and hence can be used as the basis for their identification and control. It follows that their interactions with an artificial substratum uniquely characterize them. In principle, potentially it is easier and faster to evaluate the interfacial energy between a bacterium and a substratum than to characterize its genome or determine molecular biomarkers characteristic of the strain, hence validation of this thesis opens the way to rapid screening and diagnosis. Auxiliary to this main idea, an advanced metrology for evaluating the interfacial energies has been developed, exploiting the power of kinetic analysis.

Oceans offer a vast supply of energy through ever-present winds and currents. Offshore wind energy alone could provide many times the current global energy demand. One concept approach that aims to tap into these reserves are energy sail ship, wind powered vessel that take advantage of oceanic energy to produce and store harvested energy. This report studies the different systems involved in designing an energy sail ship; finding suitable waters to operate, shell vessel design, wind propulsion method, electricity generation, and hydrogen production and storage.Suitable operating waters are identified as having strong prevailing winds and currents, as well as proximity to land. One particularly suitable example of this is the southern coast of New Zealand, which is studied in this report. Catamarans are identified for use as energy sail ship design, as they offer low water resistance as well as large surface areas needed to place systems. Three methods of ship propulsion are considered; Flettner rotors, Parawings and Wing sails. A method of effective and reliable saltwater electrolysis is identified, with cells that last thousands of hours without maintenance. Finally, hydrogen storage methods are evaluated, including chemical conversion into methanol or ammonium, as well as compressed hydrogen storage.A simplified energy analysis is preformed to determine an approximate energy efficiency of a theorized ESS that utilizes proposed technologies. The energy sail ship was found to produce roughly 2.5 GWh.
Havet innehåller stora mängder energi från både vindar och strömmar. Endast energi från kustnära vindar uppskattas vara tillräckligt för att täcka världens årliga energibehov. Ett koncept som avser att ta till vara på havets energi är vinddrivna och vätgasproducerande skepp (engelska: energy sail ships).I denna rapport studeras de olika system och teknologier som bygger upp en energy sail ship,så som lämpliga vattenområden, skeppsdesign, vinddrivningsmetod, elgenereringsmetod, vätgasproduktion och energilagring.Områden med konstanta och starka vindar, i kombination med starka havsströmmar, identifieras. Nya Zeelands södra kust är ett särskilt lämpligt område som studeras närmare i denna rapport. Katamarandesign föreslås som skeppsdesign för dess låga vattenmotstånd samt att de erbjuder det stora ytområde som behövs för vätgasproduktion och lagring. Tre metoder för vinddrivning identifieras; Flettnerrotorer, fasta segel samt skärmsegel. Energieffektiva och underhållsfria elektrolysceller föreslås för saltvattenselektrolys. Dessa celler har en livslängd på tusentals timmar istället för endast några få timmar för celler som inte är anpassade för saltvatten. Till slut utvärderas vätgaslagring i form av metanol, ammonium eller komprimerad vätgas.En enklare energianalys utförs för att bestämma energieffektiviteten av en energy sail ship som använder de föreslagna teknologierna. Detta skepp får en approximativ årlig energiproduktion på 2,5 GWh.

A sustainable world is one in which human needs are met equitably without harm to the environment, and without sacrificing the ability of future generations to meet their needs. Electrical energy is one such need, but neither the production nor the utilization are equitable or harmless. Growth of electricity availability and how we use electricity in industrialized nations has established a dichotomy between usage and sustainability. This dichotomy is best illuminated by the current "just-in-time" approach where excessive electricity generation capacity is installed to be able to instantaneously meet load from consumers at all times. Today in the United States, electricity generation capacity is approximately 3.73 kW per person versus 3.15 kW per person in 2002. [1] [2] At this magnitude of installed capacity the entire world would need approximately 25.5 TW of generation or approximately 12,250 Hoover Dams today and must add 766 MW of capacity every day. [3] This unsustainable effect is further exacerbated by the fact that consumers do not have a strong vested incentive to keep electricity generation sustainable because the producers shoulder the burden of instantaneously meeting demand.

What is needed are paradigms to make these resources economically sustainable. The opportunity provided by the smart-grid is lost if we just automate existing paradigms, hence it is new paradigms that should be enabled by the smart-grid. This dissertation examines a new paradigm which shifts the problem towards `energy delivery' rather than `power delivery' for economic sustainability. The shift from a just in time power model to an energy delivery represents a fundamental change in approach to the research happening today.

The energy delivery paradigm introduces the concept of a producer providing electrical energy to a system at a negotiated cost and within power limits, leaving the issue of balancing instantaneous power to the consumer, which has overall control on its demand and power requirements. This paradigm has potential to alter the current technical, market, and regulatory problem in electrical energy production and move the economic landscape toward electrical energy production for a more sustainable, reliable, and efficient electrical energy system. This dissertation examines concepts along the path of energy delivery which crosses many fields including power systems, data communications, controls, electric markets, and public utility regulation ultimately proposing a mathematical formulation and solution. The dissertation then shifts to examining potential physical interpretations of the formulation and solution and impacts to different fields within the energy paradigm.

Vibration measurements conducted in three vehicles windshields are used to determine frequency content in the windshield of moving vehicles. A piezoelectric energy harvester is modeled, and used in simulations to determine output voltage and power with measured acceleration signal as input.

The energy and power used at various areas like households and industries is increasing gradually due to many reasons and there is a need to sustain it. This project introduces a method to reduce the energy used in a household by considering the energy sources and the amount of energy used by the appliances concurrently. Modules are used to measure and check the energy utilized by the appliances using ZigBee. Energy is generated on a conventional basis using three sources: solar panel, wind mill and conventional power. An inverter and a battery are used to connect these sources to a grid. When a device is connected, the units of power consumed are computed and shown on the LCD using LPC2148 microcontroller. The output of the battery is connected to the controller, which shows the voltage of the battery and also selects the best source to be used. Modules use a 5V supply and the controller uses 3.3V power supply. Voltage is controlled with the help of a 7805 voltage regulator and the output of transformer is revised by a rectifier.

This work is investigating how energy policy instruments can be depicted explicitly in DiDo, the re-gional agent-based energy transition model for the Netherlands designed by the TNO. Within DiDo the transition of the energy system is considered a result of individual transformations of the different stake-holders in the system. The focus of this work lies on household agents, their investment decision making and the effects of policy instruments on this microeconomic level. Bounded rationality, heuristics and individual attitudes and perceptions are identified to play a relevant role when investing in energy assets and thus an explicit parameterization of these particularities of human behavior is proposed. The model-ing of the investment decision is following a rational approach originating from finance that features the Markowitz portfolio optimization, which is relying on the return of investments (ROI) in assets. In order to incorporate behavioral aspects and perceptions into this rational frame, the concept of subjective ROI is introduced. Arising from recent developments in behavioral economics, this concept is in line with the observations made on financial markets that challenge the long maintained assumption of normally dis-tributed ROI distributions. Finally, surveying individual willingness to pay for energy assets and testing the correlation with behavioral and policy instrument aspects using a regression analysis is proposed as the subsequent methodological step.
Det här arbetet undersöker hur energipolitiska instrument kan avbildas uttryckligen i DiDo, den regionala agentbaserade energitransitionsmodellen för Nederländerna, designad av TNO. Inom DiDo anses skiftet av energisystemet vara ett resultat av individuella omvandlingar av de olika intressenterna i systemet. Inriktningen för detta arbete låg på hushållsmedlemmar, deras investeringsbeslutsfattande och effekterna av politiska instrument på denna mikroekonomiska nivå. Bundet rationalitet, heuristik och individuella attityder och uppfattningar identifierades för att spela en relevant roll när man investerar i energitillgångar och därmed föreslagits en explicit parametresering av dessa särdrag av mänskligt beteende. Modelleringen av investeringsbeslutet följer en rationell strategi som härrör från finansiering som använder Markowitz-portfölje optimering, som är beroende av avkastning av investeringar (ROI) i tillgångar. För att integrera beteendeaspekter och uppfattningar i denna rationella ram introduceras koncept av subjektivt ROI. På grund av den senaste utvecklingen inom beteendeekonomin ligger detta koncept i linje med observationerna på de finansiella marknaderna som utmanar det gammalt antagna-det om normalt fördelade avkastnings fördelningar. Slutligen föreslås undersökning av individuell vilja att betala för energitillgångar och testa korrelationen med beteendemässiga och politiska instrumentaspekter med hjälp av en regressionsanalys som det efterföljande metodologiska steget.

Thesis: Ph. D., Massachusetts Institute of Technology, Engineering Systems Division, 2015.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 185-198).
The dissertation examines conditions under which gas-to-liquids (GTL) technology penetration shifts the crude oil-natural gas price ratio. Empirical research finds long-run relationships between crude oil and natural gas prices. Some studies include time trends that steadily evolve the pricing relationship, while others show a long-run relationship that occasionally shifts significantly. A common hypothesis is that technologies that increase substitutability or complementarity between fuels are the source of the price linkage. However, empirically measuring the effects of a gradually-penetrating technology across narrow time frames is not possible due to intervening economic shocks. This thesis examines the effects of an energy conversion technology penetration on the crude oil-natural gas price ratio through its influence on sectoral energy use in the U.S. GTL must be less expensive and more efficient, and natural gas prices must be lower, than currently forecast for an effect to be measured. In the absence of a technology that explicitly allows for substitution between natural gas and petroleum-based fuels, different rates of demand growth result in a steadily-rising oil-gas price ratio. If a viable GTL technology successfully competes against petroleum-derived refined fuels, it dampens crude oil price increases and brings the oil-gas price ratio below the levels found in cases without a viable GTL technology.
by David John Ramberg.
Ph. D.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.
Includes bibliographical references (p. 122-127).
This thesis concerns the concepts, structure, and applications of the Alternative Energy Design Toolkit. The toolkit is aimed to provide a widely accessible, easy to use, flexible, yet powerful modeling environment for assisting design associated with renewable energy technologies. Exchanges of ideas and knowledge among the users are also highly encouraged and facilitated. The toolkit is composed of three important components: a collection of models that are fundamentals of renewable energy design, a modeling environment called DOME, which is used as the toolkit's enabler, and a supporting Web site. At the beginning, a comprehensive survey of existing tools for renewable energy design is presented. Then, the detailed descriptions and key capabilities of the toolkit's components are provided. In addition, a collection of solar energy models, which is the initial set of models in the toolkit, is also presented. The toolkit is utilized in two design scenarios: a design of a stand-alone PV system, and a trade-off analysis of a hybrid PV-diesel electricity system. In both design scenarios, the models in the toolkit are proven to be useful and convenient resources. The processes of making the representations of the systems are straight-forward, and the analysis mechanisms that the toolkit provides make the design process simple yet effective.
by Sittha Sukkasi.
S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 205-213).
The substantial growth in industrial production, demand for materials, and population has led to an increasing need for sustainable manufacturing processes to mitigate the negative impacts on the environment and meet the needs of future generations. One proposed direction is remanufacturing, which is a process whereby used products having reached their end-of-life, are restored back to useful service-life. Remanufacturing utilizes the energy and embedded value retained in a product upon reaching end-of-life. Remanufacturing can close the loop between disposal and supply chains, extend the service lifetime of products, conserve resources, and help mitigate environmental consequences attributed to landfilling. Moreover, by preserving the geometrical architecture of cores, remanufacturing can reduce the needs for raw material processing and many manufacturing processes, hence, saving energy. A critical issue to consider when evaluating energy savings in remanufacturing is the product use phase: how well does the remanufactured device perform in the use phase compared to a similar new product from an energy standpoint? To answer this question, we utilize Life Cycle Assessments framework. Using this methodology, we quantify cumulative energy demands of a remanufactured product during its lifecycle and compare it to an equivalent new product. We conduct an analysis of lifecycle energy savings of remanufacturing for 19 different products in 8 distinct product case studies (4 product case studies discussed in detail in this thesis).
(cont.) By performing lifecycle evaluations we conclude that remanufacturing can be a net energy-saving option for products that have energy requirements dominated by the production phase. Moreover, our energy analysis sheds light on the importance of considering use phase while evaluating the energy savings potential of remanufacturing. We conclude that from a total life cycle perspective, remanufacturing may be a net energy saving as well as a net energy expending end-of-life option. We argue that in investigating energy savings of remanufacturing as an end-of-life option, one should also evaluate large-scale critical factors in order to effectively address the systems challenges associated with remanufacturing. Our retrospective approach signifies the importance of studying critical factors such as technological improvements, policy interventions, economic incentives, and business models in order to draw inferences about energy and economic savings potential of remanufacturing. In addition, we argue that the generalized claims about remanufacturing as the ultimate end-of-life option are not only subject to dynamic global changes, but also restricted by the limitations in the lifecycle environmental methodologies. Lastly, we conclude that the evaluations for product remanufacturing and energy savings are more valuable and justified if conducted on a case-by-case basis.
by Avid Boustani.
S.M.

The European Council has recently set objectives in the matter of energy and climate policies and thus the interest in renewable energies is more than ever at stake. However, the introduction of renewable energies in an energy mix is also accelerated and altered by political targets. The two most widespread renewable technologies, photovoltaic and wind farms, have specific characteristics - decentralized, intermittency, uncertain production forecast up until a few hours ahead - that oblige to adapt the network and the current conventional generator control. By using optimization techniques, it is possible to characterize the optimal energy mix (i.e. the optimal share of every power technology in all the countries considered). In this paper, the optimization function is defined as the sum of the yearly fixed cost of deploying a certain amount of installed capacity with the cost of electricity generation over the while year. Then the aim of the model is to evaluate the energy mix of least cost. One can imagine multiple applications for this model, depending on which issue is to solve. Two case studies are developed in this report as examples. Renewable technologies are modifying the organization of the electricity market because of their specific characteristics. The first case study aims at quantifying the additional cost due to the integration of renewable energies. The second is targeted to characterize the impact of the integration of green energy sources on the deployment of Demand Response.

Increased share of Renewable Energy Sources (RES) in the generation mix requires higher flexibility in power system resources. The intermittent nature of the RES calls for higher reserves in power systems to smooth out the unpredictable power fluctuations. Grid-tied energy storage systems are practical solutions to facilitate the massive integration of RES. The deployment of Battery Energy Storage Systems (BESS) on the power grids is experiencing a significant growth in recent years. Thanks to intensive research and development in battery chemistry and power conversion systems, BESS costs are reducing. However, much more advancements in battery manufacturing as well as additional incentives from the market side are still needed to make BESS a more cost-effective solution. Planning and operation of the BESS significantly influence its profitability. It is quite important to find optimal sizes of batteries and inverters. Sizing of the BESS for two different applications is addressed in this work. In the first application, the BESS is co-located with Pumped Storage Hydro (PSH) to meet the Day-Ahead (DA) schedule of wind generation. In the second application, a method for BESS sizing in the presence of PV-induced ramp rate limits is proposed. In this thesis, two methods based on Receding Horizon Control (RHC) for the optimal operation of the BESS are introduced. A co-located BESS and wind farm is considered in both methods. In one method, electricity market participation is not considered, and the goal is solely meeting the DA schedule utilizing the BESS. A novel predictive control method is proposed in this part and the efficiency of the method is evaluated through long-run simulations using actual historical wind power.

In the second scenario, market participation of the BESS is taken into account. The deviation from the DA schedule can be compensated through the BESS, or by purchasing power from the real-time electricity market. The optimization problem based on physical and operational constraints is developed. The problem is solved through an RHC scheme while using updated wind power and electricity price forecasts. In this thesis, a Ridge-regression forecast model for electricity price and an ARIMA forecast model for wind power are developed. Simulation results using actual historical data for wind power and electricity price demonstrate that the proposed algorithm increases the average daily profit. In order to evaluate the impact of the BESS lifetime and price on average daily profit, different scenarios are defined and simulated. Although they increase the complexity of the problem, much more realistic result might be obtained when all details and constraints are considered.

Includes bibliographical references.
In this thesis the author investigated the use of a Q-learning based path planning algorithm to investigate how effective it is in saving energy. It is important to pursue any means to save energy in this day and age, due to the excessive exploitation of natural resources and in order to prevent drops in production in industrial environments where less downtime is necessary or other applications where a mobile robot running out of energy can be costly or even disastrous, such as search and rescue operations or dangerous environment navigation. The study was undertaken by implementing a Q-learning based path planning algorithm in several unstructured and unknown environments. A cell decomposition method was used to generate the search space representation of the environments, within which the algorithm operated. The results show that the Q-learning path planner paths on average consumed 3.04% less energy than the A* path planning algorithm, in a square 20% obstacle density environment. The Q-learning path planner consumed on average 5.79% more energy than the least energy paths for the same environment. In the case of rectangular environments, the Q-learning path planning algorithm uses 1.68% less energy, than the A* path algorithm and 3.26 % more energy than the least energy paths. The implication of this study is to highlight the need for the use of learning algorithm in attempting to solve problems whose existing solutions are not learning based, in order to obtain better solutions.

The excessive energy consumption of backbone networks is causing concerns among network operators. This thesis focuses on the design of Energy-aware Traffic Engineering (ETE) schemes which improve the energy-efficiency of different backbone networks by enabling the delivery of traffic by the smallest number of network devices so that the remaining devices can go to sleep during the periods of low traffic demands. The first proposed ETE scheme is called Time-driven Link Sleeping (TLS) which uses only two network routing topologies: the full topology with all links being active, and a reduced one with a subset of links sleeping. The key novelty of TLS lies in its ability to jointly optimize the reduced network topology and the off-peak period during which it is operated. Moreover, an extension to TLS makes it robust to single link failures. The second ETE scheme is a Green Load-balancing Algorithm (GLA) which complements TLS and other existing ETE schemes by jointly optimizing the IGP link weights in backbone networks for improved load-balancing and energy-efficiency after these existing ETE schemes put links to sleep. The final contribution is an online distributed ETE scheme called Green. Backup Paths (GBP) which dynamically diverts traffic from some selected links onto their backup paths, which were pre-installed to protect against link failure, so that these links have the opportunity to go to sleep without affecting the primary purpose of the backup paths. The distributed nature of GBP makes it scalable to large networks and be very responsive to sudden traffic changes since multiple routers can concurrently make interference-free decisions. The simple TLS scheme with GLA is ideally suited for networks which experience a regular traffic pattern because of their , offline nature while the more 'complex GBP scheme is more suitable when there is dynamic traffic because of its online nature.

Approved for public release; distribution is unlimited
The U.S. Navy anticipates moving to a shipboard high-energy laser program of record in the fiscal year 2018 and achieving an initial operational capability by 2020. The design of a distance support capability within the high-energy laser system was expected to assist the Navy in reaching this goal. This capstone project explored the current Navy architecture for distance support and applied system engineering methodologies to develop a conceptual distance support framework with application to the high-energy laser system. A model and simulation of distance support functions were developed and used to analyze the feasibility in terms of performance, cost, and risk. Results of this capstone study showed that the implementation of distance support for the high-energy laser system is feasible and would reduce the total ownership cost over the life of the program. Furthermore, the capstone shows that moving toward the team’s recommended distance support framework will address current gaps in the Navy distance support architecture and will provide a methodology tailored to modern enterprise naval systems.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 159-168).
Human intellectual desire inspires recent research to expand to interdisciplinary areas across biology, chemistry, and physics. Interdisciplinary research in unexplored areas is challenging, but holds great promise to elucidate what people did not see before. Scientific discoveries bring us not only intellectual pleasures, but also opportunities to contribute to the advancement of mankind. Photosynthesis is a representative interdisciplinary research field. Conducting research in photosynthesis requires a collaborative work of biology, photochemistry, and quantum physics. Nature has optimized photosystems in bacteria, algae, and plants over three billion years in an evolutionary fashion to utilize solar energy for their survival. The way nature has mastered such systems can provide insights into designing efficient solar energy conversion applications. This thesis explores artificial photosystems as proofs of nature's design concept using a biological scaffold of M13 bacteriophage. The main ideas in the thesis focus on maximizing transport phenomena in the systems, resulting in performance improvements. Genetic engineering of M13 bacteriophage enables nano-scale multi-component assemblies to create tunable, artificial photosystems for solar energy utilization. Artificial photosystems include light-harvesting antenna complexes and oxygen-evolving photocatalytic systems. In particular, a solid collaboration with Seth Lloyd's theory group inspires me to design a quantum light-harvesting antenna complex. The genetically engineered light-harvesting antenna complex creates a chromophore network interplaying between quantum and semi-classical mechanisms, thus maximizing exciton transport.
by Heechul Park.
Ph. D.

This thesis concerns the transport of light along a class of cylindrical hollow optical structures, with an aim to develop practical light transport and distribution systems for illuminating engineering applications. Based on intuition, it is postulated that it may be possible to guide light energy in a hollow cylindrical optical structure, by means of total internal reflection on the external surfaces. Such a development would allow light to be guided with the efficiency of optical fibres, but with reduced material costs. In order to assess this possibility, a new technique is presented for analytic ray tracing in general cylindrical structures. The technique makes it possible to trace ray paths in the cross sectional plane of the structure, with the motion in the dimension out of the cross sectional plane precisely taken into account with a simple correction. This technique greatly simplifies the ray tracing calculations which are necessary to study the light transport properties of the proposed structures. It is then shown with the aid of this technique that a certain class of prismatic structures do indeed have the capability of guiding light, and members of this class are termed prism light guides. In any real prism light guide, light is not conducted perfectly, but is lost as a result of a number of deviations from the ideal model. Of these, the one intrinsic loss mechanism, which distinguishes a prism light guide from optical fibres, is diffraction at the corners of the prismatic surfaces. Fortunately, diffraction effects are significantly smaller than losses from practical imperfections in prism light guides. A detailed study of the other types of loss mechanisms is then presented. These arise from imperfections of the optical material comprising the prism light guide (absorption and scatter), and imperfections in the shape of the prism light guide. The importance of these effects is discussed first in an approximate assessment, and they are then modelled precisely by means of computer ray tracing Monte Carlo techniques. These predictions are compared with experimental measurements of actual prism light guides, with substantial agreement. Consideration is then given to the use of a prism light guide in illuminating engineering applications. In these situations light is distributed along the length of a prism light guide, and is uniformly emitted from the surface. The performance of such a system is modelled with Monte Carlo computer ray tracing, and experimentally tested, with substantial agreement. This study concludes with a measurement of diffraction losses. These losses were enhanced by the use of longer wavelength radiation (3mm wavelength microwaves). The results confirm that diffraction losses are small relative to other loss mechanisms. In general, the results reported in this thesis demonstrate the existence of a useful class of light guidance structures which are particularly well suited to the requirements for distribution and transport of optical radiation for illuminating engineering applications.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

Hydrothermal carbonisation (HTC) could form the basis for rendering human faecal wastes safe whilst at the same time generating a carbon-rich material (hydrochar) and providing prospects for the recovery of energy. The work presented here has an objective of the search for optimal conditions for the HTC conversion of human faecal waste. Primary sewage sludge (PSS) and synthetic faeces (SF), of various moisture contents, were used as feedstocks to investigate the kinetics of decomposition of solids during HTC over a range of reaction times and temperatures. Decomposition was found to follow first-order kinetics, and the corresponding activation energies were obtained. Temperature was of primary importance to influence solid decomposition. Higher temperatures resulted in higher solids conversion to hydrochar. The energy contents of the hydrochars from PSS carbonised at 140 200oC for 4 h ranged from 21.5 to 23.1 MJ kg 1. Moisture content was found to affect the HTC process and feedstocks, with higher initial moisture contents resulted in lower hydrochar yields. The effect of reaction conditions on the characteristics of the hydrochar, liquid and gas products from HTC of faecal material, and the conditions leading to optimal hydrochar characteristics were investigated using a Response Surface Methodology (RSM). Models were developed here which could aid in the identification of reaction conditions to tailor such products for specific end uses. The results showed that the amount of carbon retained in hydrochars decreased as temperature and time increased, with carbon retentions of 64 77% at 140 and 160oC, and 50 62% at 180 and 200oC. Increasing temperature and reaction time increased the energy content of the hydrochar from 17 19 MJ kg 1 but reduced its energy yield from 88 to 68%. HTC at 200oC for 240 min resulted in hydrochars suitable for fuel, while carbonation at 160oC for 60 min produced hydrochars appropriate for carbon storage when applied to the soil. Theoretical estimates of methane yields resulting from subsequent anaerobic digestion (AD) of the liquid by-products are presented, with the highest yields obtained following carbonisation at 180oC for 30 min. In general, HTC at 180oC for 60 min and 200oC for 30 min resulted in hydrochars having optimal characteristics, and also for obtaining optimal methane yields. Maillard reaction products were identified in the liquid fractions following carbonisations at the higher temperatures. It was also found that the TOC, COD and BOD of the liquid products following HTC increased as the reaction temperature and time were increased and that these would require further treatment before being discharged. The results indicated that the gaseous phase following HTC contained carbon dioxide, nitrogen dioxide, nitric oxide, ammonia, and hydrogen sulphide indicating that additional treatment would be required before discharge to the atmosphere. In order to identify the optimum conditions leading to greater filterability of slurry resulted from HTC, the effects of reaction temperature and time on the filterability of PSS and SF slurries were investigated and optimised using RSM. It was shown that filterability improved as the reaction temperature and time at which the solids were carbonised was increased, with the best filtration results being achieved at the highest temperature (200°C) and longest treatment time (240 min) employed here. The specific cake resistance to filtration of the carbonised slurries was found to vary between 5.43 x 1012 and 2.05 x 1010 m kg 1 for cold filtration of PSS, 1.11 x 1012 and 3.49 x 1010 m kg 1 for cold filtration of SF, and 3.01 x 1012 and 3.86 x 1010 m kg 1 for hot filtration of SF, and decreased with increasing reaction temperature and time for carbonisation. There was no significant difference in specific resistance between cold and hot filtration of SF. The RSM models employed here were found to yield predictions that were close to the experimental results obtained, and should prove useful in designing and optimising HTC filtration systems for generating solids for a wide variety of end uses. Mass and energy balances of a semi-continuous HTC of faecal waste at 200oC and a reaction time of 30 min were conducted and based on recovering steam from the process as well energy from the solid fuel (hydrochar) and methane from digestion of the liquid by-product. The effect of the feedstock solids content and the quantity of feed on the mass and energy balances were investigated. Preheating the feed to 100oC using heat recovered from the process was found to significantly reduce the energy input to the reactor by about 59%, and decreased the heat loss from the reactor by between 50 60%. For feedstocks containing 15 25% solids (for all feed rates), energy recycled from the flashing off of steam and combustion of the hydrochar would be sufficient for preheating the feed, operating the reactor and drying the wet hydrochar without the need for any external sources of energy. Alternatively, for a feedstock containing 25% solids for all feed rates, energy recycled for the flashing off of steam and combustion of the methane provides sufficient energy to operate the entire process with an excess energy of about 19 21%, which could be used for other purposes.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2000.
Includes bibliographical references (leaves 58-60).
by Amit Sinha.
S.M.

In the UK, the domestic sector accounts for around 30% of fuel-use and energy related carbon emissions, and therefore has the potential to deliver significant reductions in carbon dioxide emissions. The purpose of this work is to form and examine various heat and electricity supply scenarios at the street-level and identify which of these scenarios offer the most potential to reduce consumption of resources and carbon dioxide emissions. The path to realisation of a reduction in carbon emissions from the domestic sector incorporates three consecutive steps: (1) saving energy, (2) use of renewables and (3) use energy as efficiently as possible, including fossil fuels. In reality, there is a strong interaction between all three steps and often they take place simultaneously. The first two steps tend to minimise the use of fossil fuels, but not to eliminate them. In this work it is recognised that in mature urban regions fossil fuels cannot be readily displaced completely, but can be used in a more efficient way. This research considers what can be achieved by applying at or near to market technologies at the street level microgrid scale, such as Combined Heat and Power (CHP). The renewable energy technologies considered were photovoltaics (PV) for electricity generation, solar thermal for domestic hot water heating and ground source heat pumps (GSHP) for space heating. For the development of the models, the transient simulation package TRNSYS was used and a residential area in Southampton that represents a typical UK area, was chosen as a case study. The notion of combining a number of houses to form a local microgrid proved to be beneficial for all the technologies examined in this research. It was shown that renewable energy microtechnologies can improve their carbon performance up to 10% when operating as a microgrid, whilst estimated benefits were even greater for CHP systems. Parallel operation strategies were also investigated and it was shown that they have the potential to deliver further savings from microgrid schemes. Microgrids, although their high capital costs, were estimated to have better financial performance compared with the single house level for many of the cases examined. Increased generation and lower heating demand were the key outcomes due to the impact of change in climate

This investigation explores the use of an approximate energy flow approach to provide a global modelling tool capable of predicting the pattern and level of vibrational energy flow in complex structures. The modelling approach is based on a differential control volume formulation which, by virtue of its simplified nature, describes the flow of mechanical energy within a structural component in a manner analogous to the flow of thermal energy in heat conduction problems. For complex structures the approach can be implemented using existing finite element software through an analogy between the thermal and vibrational systems. Energy flow predictions along simple beam structures, obtained using the energy flow approach, are compared to "exact" analytical solutions and experimental structural intensity measurements on real structures. This provides useful insight into the capabilities and requirements of the approach, such as the quality of model predictions at lower frequencies and the accuracy requirement for modelling parameters. The task of modelling the transmission of vibrational energy in practical engineering structures is complicated by the partial reflection of incident wave energy at structural discontinuities. Methods to account for this effect are discussed and an approach is developed which can be incorporated into the finite element global modelling scheme. This is used to model a complex multiple transmission path structure which illustrates the ability of the approach to form an effective transmission path ranking tool. Finally, the approach is used to build a representative energy flow model of a ribbed bulkhead structure typical of marine applications. A wavenumber measurement technique is used to assess the wave transmission characteristics of this structure which exhibit strong directional dependence. Predictions provided by the energy flow model are in good general agreement with energy flow measurements obtained from the real structure. Throughout these modelling exercises particular attention is paid to the provision of suitable estimates of the parameters (damping, group velocity, power input and transmission efficiency) on which the accuracy of the model predictions rely. This investigation represents a significant contribution to current knowledge regarding the use of the energy flow approach and its ability to provide representative models of real structures. Although further research is still required, considerable progress has been made and the work documented here provides the framework for a global modelling tool using existing finite element software.

Master of Science
Department of Mechanical Engineering
Donald Fenton
The need to store and access electronic information is growing on a daily basis as more and more people conduct business and personal affairs through email and the internet. To meet these demands, high energy density data centers have sprung up across the United States and around world. To ensure that vital data centers run constantly, proper cooling must be maintained to prevent overheating and possible server damage from occurring. Emergency cooling systems for such systems typically utilize traditional batteries, backup generator, or a combination thereof. The electrical backup provides enough power to support cooling for essential components within the data centers. While this method has shown to be reliable and effective, there are several other methods that provide reliable emergency cooling at a fraction of the cost. This paper address the lack of information regarding the initial, operation, and maintenance costs of using Thermal Energy Storage (TES) tanks for emergency cooling. From research and various field examples, five emergency cooling system layouts were designed for various peak cooling loads. Looking at the different cooling loads, components, and system operations an economic evaluation of the system over a 20 year period was conducted. The economic analysis included the initial and maintenance costs of each system. In an effort to better understand power consumption of such systems and to help designer’s better estimate the long term costs of TES tanks systems, five layouts were simulated through a program called TRNSYS developed for thermal systems. To compare against current systems in place, a benefit to cost ratio was done to analyze TES versus a comparable UPS. The five simulated systems were one parallel pressurized tank, one parallel and one series atmospheric tank, one parallel low temperature chilled water, and one series ice storage tank. From the analysis, the ice storage and pressurized systems were the most cost effective for 1 MW peak cooling loads. For 5 MW peak cooling loads the ice storage and chilled water systems were the most cost effective. For 15 MW peak loads the chilled water atmospheric TES tanks were the most cost effective. From the simulations we concluded that the pressurized and atmospheric systems consumed the least amount of power over a 24 hour period during a discharge and recharge cycle of the TES tank. From the TRNSYS simulations, the ice storage system consumed 22 – 25% more energy than a comparable chilled water system, while the low temperature storage system consumed 6 – 8% more energy than the chilled water system. From the benefit-cost-ratio analysis, it was observed that all systems were more cost effective than a traditional battery UPS system of comparable size. For the smaller systems at 1 MW the benefit-cost-ratio ranged between 0.25 to 0.55, while for larger systems (15 MW) the ratio was between 1.0 to 3.5 making TES tanks a feasible option for providing emergency cooling for large and small systems.

The fourth industrial revolution is here and with it a tidal wave of challenges for its prosperous implementation. One of the greatest challenges frustrating the development of the internet of things, and hence the next industrial revolution, is the powering of wireless sensors, as these depend on batteries with a limited lifetime. Recent advances have shown that energy harvesting technologies can be employed to extend the lifetime of batteries and ultimately replace them, thus facilitating the deployment of autonomous self-powered sensors, key components of the internet of things. Energy harvesting is the process of capturing ambient energy and convertingit into electric power. For energy harvesting devices it is crucial that the transduction of energy is as efficient as possible, meaning that the methods for capturing, interfacing and converting the ambient energy should be understood and characterized for every application. This thesis investigates the harvesting of the energy found in pressure fluctuations in hydraulic systems, a widely used power transmission system used in the industry and consumer applications; the focus is on the fluid interface and energy focusing methods. In summary, the contributions in this thesis show that the methods for converting pressure fluctuations in hydraulic systems to electrical power depend on the hydraulic system environment, in essence, the static pressure and the frequency of the pressure fluctuations. The results can serve as a starting point in the research, design, and development of hydraulic pressure energy harvesters.
Den fjärde industriella revolutionen är här vilket innebär en rad utmaningar för att dess utveckling ska bli framgångsrik. En av de största utmaningarna som begränsar utvecklingen av sakernas internet för industriella tillämpningar är strömförsörjningen av trådlösa sensorer då dessa är beroende av batterier med begränsad livslängd. Nya framsteg har emellertid gjorts med tekniker för energiskördning som gör att livslängden för batterierna kan förlängas ochi förlängningen helt ersätta batterierna. Det, i sin tur, möjliggör autonoma sensorer som är självförsörjande på energi som är viktiga komponenter i sakernas internet. Energiskördning är den process som omvandlar energi som finns i omgivningen till elektrisk energi. För att kunna få ut så mycket energi som möjligt så är det avgörande att energiskördarna gör energiomvandlingen så effektivt som möjligt. Det gör att inhämtning av omgivande energi samt gränssnitt och energiomvandling måste förstås och karakteriseras för varje tillämpning. Den här avhandlingen undersöker energiskördning för hydrauliskasystem där tryckfluktuationer i dessa system är energikällan. Syftet med den här studien är att ta fram metoder för uppskattning och karakterisering av de nödvändiga gränssnitten för inhämtning, fokusering, och omvandling av fluktuationer i hydraultryck till elektrisk energi. Sammanfattningsvis visar avhandlingen att metoder för att omvandla tryckfluktuationer i hydraulsystem till elektrisk energi beror på den hydrauliska systemmiljön där det statiska trycket och frekvensen av tryckfluktuationerna är de viktigaste parametrarna. Resultaten kan fungera som utgångspunkt för fortsatt forskning och utveckling av energiskördare för hydrauliska system.
SMART (Smarta system och tjänster för ett effektivt och innovativt samhälle)

With the amazing increase in mobile data traffic, the fast-growing requirement for, and development of, green communication technology has led to many energy-saving designs in mobile networks. Meanwhile, as advanced cellular technologies progress, more than one component carrier (CC) can now be jointly utilized in a base station (BS).

As a result, the energy consumption of the base station (BS) has become an important concern. In this research, a novel green rate-and-power control transmission scheme is studied and implemented at the BS transmission. The purpose of this scheme is to address the problem of energy minimization at BS transceivers, while maintaining certain quality-of-service and fairness for all users.

Furthermore, the Energy Adaptive Rate Control Algorithm (EARCA) is applied in Stanford University Interim (SUI-3) Channel Model. After adding a fourth energy level to EARCA, and comparing this model with the existing three-level EARCA model, an analysis of how this strategy affects the number of Non-Real Time users and energy consumption was performed.

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 74-78).
Interest in urban energy modeling has grown among planners and policy-makers as more and more municipalities set targets for reduction of greenhouse gas emissions. Urban-scale building energy models can help evaluate the efficiency of proposed district designs, consequences of building retrofit interventions, or energy supply options. Bottom-up models based on physical descriptions and engineering calculations are the most versatile for modeling scenarios and evaluating results at high spatial and temporal resolutions. Such urban building energy models (UBEMs) are typically created by grouping buildings with similar properties into archetypes, which standardize many properties that are not uniform in reality, such as occupancy-driven parameters. Since most UBEMs are validated using aggregated, annual measured data, this standardization is usually adequate; however, for a more accurate model that considers end-use differentiation or seasonal variation, neither this standardization nor this validation method are sufficient. This work proposes a new methodology for archetype definition and customization using metered monthly energy data. Customization is done by inferring certain parameters from the energy data and estimating others probabilistically from parametric analysis. The methodology is developed and tested on a case study of 453 low-rise residential buildings in Cambridge, Massachusetts. Four model iterations are compared: single template, eight archetype templates, eight archetypes with individual building customization, and the latter with the addition of parametric analysis and generation of frequency distributions for unknown parameters. The results show an improvement in mean goodness of fit from 46% with one template and 37% with eight templates to 18% for the final iteration. The distribution of energy use intensities, as well as monthly electricity and gas profiles, approach observed values closer with each iteration. The results also demonstrate that error metrics based on aggregated annual consumption, commonly used for urban model validation, are not necessarily representative of the model's fit on a monthly basis.
by Julia A. Sokol.
S.M.