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An integrated energy storage scheme for a dispatchable wind and solar powered energy systemGarrison, Jared Brett 23 August 2010 (has links)
Wind and solar technologies have experienced rapid market growth recently as a result of the growing interest for implementation of renewable energy. However, the intermittency of wind and solar power is a major obstacle to their broader use. The additional risks of unexpected interruptions and mismatch with demand have hindered the expansion of these two primary renewable resources.
The goal of this research is to analyze an integrated energy system that includes a novel configuration of wind and solar coupled with two storage methods to make both wind and solar sources dispatchable during peak demand, thereby enabling their broader use. Named DSWiSS for Dispatchable Solar Wind Storage System, the proposed system utilizes compressed air energy storage (CAES) that is driven from wind energy and thermal storage supplied by concentrating solar thermal power in order to achieve this desired dispatchability. Although DSWiSS mimics the operation of a typical CAES facility, the replacement of energy derived from fossil fuels with energy generated from renewable resources makes this system unique. While current CAES facilities use off peak electricity to power their compressors, this system uses power from wind turbines. Also, rather than using natural gas for heating of the compressed air before its expansion through a turbine, DSWiSS uses solar thermal energy and thermal storage.
For this research, two models were created; the first is a dynamic model of a 1.5 MW variable speed wind turbine, programmed in PSCAD/EMTDC, that utilizes rotor resistive control to maintain rated power output. This model simulates the dynamic response of the wind turbine to changing wind conditions as well as the nominal performance parameters at all wind speeds. The second model is a steady state thermodynamic simulation of the turbomachinery power unit in the DSWiSS facility. By assuming conditions similar to those of a currently operating CAES facility in McIntosh, Alabama, the model calculates the performance parameters of DSWiSS and estimates the relative energy input requirements. By combining these models with a levelized lifetime cost analysis estimates of the power system performance and the cost of energy for the DSWiSS facility were estimated. The combination of these components yielded an efficiency greater than 46% for the main power block and a nearly equal utilization of both renewable resources. It was also estimated that the overall system is only slightly more expensive per unit of electricity generated than the current technologies employed today, namely coal, nuclear, and natural gas, but is comparable to a stand-alone solar thermal facility. However, this economic analysis, though accurate with regard to the technologies chosen, will not be complete until cost values can be placed on some of the externalities associated with power generation such as fuel cost volatility, national security, and emissions. / text
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Energy Storage System for Wind-Diesel Power System in Remote LocationsCordeiro, Roberto January 2016 (has links)
The aim of this thesis is to show how much fuel can be saved in a power system based in diesel generators with integrated wind turbine (WDPS – Wind Diesel Power System) when a storage system is integrated. Diesel generator is still the most used power system for remote locations where the conventional grid doesn’t reach and its integration with wind turbine is seen as a natural combination to reduce diesel consumption. However, the wind intermittency brings some challenges that might prevent the necessary diesel savings to the level that justifies the integration with wind turbine. The introduction of a storage system can leverage the wind energy that would otherwise be wasted and use it during periods of high demand.The thesis starts by describing the characteristics of energy storage systems (ESS) and introducing the major ESS technologies: Flywheel, Pumped Hydro, Compressed Air and the four main battery technologies, Lead Acid, Nickel-Based, Lithium-ion and Sodium-Sulphur. The aim of this step it to obtain and compile major ESS parameters to frame then into a chart that will be used as a comparison tool.In the next step, wind-diesel power systems are described and the concept of Wind Penetration is introduced. The ratio between the wind capacity and diesel capacity determines if the wind penetration is low, medium and high and this level has a direct relation to the WDPS complexity. This step also introduces important concepts pertaining to grid load and how they are affected by the wind penetration.Next step shows the development of models for low, medium and high penetration WDPS with and without integrated ESS. Simulations are executed based on these models in order to determine the diesel consumption for each of them. The simulations are done by using reMIND tool.The final step is a comparative study where the most appropriated ESS technology is chosen based on adequacy to the system, system size and location. Once the technology is chosen, the ESS economic viability is determine based on the diesel savings obtained in the previous step.Since this is a general demonstration, no specific data about wind variation and consumer demand was used. The wind variation, which is used as the input for the wind turbine (WT), was obtained from a typical Weibull Distribution which is the kind of distribution that most approximate a wind pattern for long term data collection. The wind variation over time was then randomly generated from this distribution. The consumer load variation is based on a typical residential load curves. Although the load curve was generated randomly, its shape was maintained in conformity with the typical curves.This thesis has demonstrated that ESS integrated to WDPS can actually bring a reasonable reduction in diesel utilization. Even with a wind pattern with a low mean speed (5.31 m/s), the savings obtained was around of 17%.Among all ESS technologies studied, only Battery Energy Storage System (BESS) showed to be a viable technology for a small capacity WDPS. Among the four BESS technologies studied, Lead-Acid presents the highest diesel savings with the lower initial investment and shorter payback time. / O objetivo dessa tese é determinar quanto combustível pode ser economizado quando se integra um sistema de armazenamento de energia (ESS na sigla em Inglês) a um sistema gerador baseado em gerador diesel integrado com turbina eólica (WDPS na sigla em Inglês). Geradores à diesel são largamente utilizados em áreas remotas onde a rede de distribuição de eletricidade não chega, e a integração de geradores à diesel com turbinas eólicas se tornou a combinação usual visando a economia de combustível. No entanto, a intermitência do vento cria alguns desafios que podem inclusive tornar essa integração inviável economicamente. A introdução de ESS à esse sistema visa o aproveitamento da energia que seria desperdiçada para usá-la em periodos de alta demanda.A tese começa descrevendo as características de ESS e suas principais tecnologias: Flyweel, hidroelétrica de bombeamento, ar-comprimido e as quatro principais tecnologias de bateria, Chumbo-Ácido, Níquel, Íon de Lítio e Sódio-Sulfúrico. O objetivo dessa etapa é obter os principais parâmetros de ESS e apresentá-los numa planilha para referência futura.Na etapa seguinte, geradores à diesel são descritos e é introduzido o conceito de Penetração do Vento. A razão entre a capacidade eólica e a capacidade do gerador diesel determina se a penetração é baixa, média ou alta, e esse nível tem uma relação direta com a complexidade do WDPS. Nessa etapa também são introduzidos importantes conceitos sobre demanda numa rede de distribuição de eletricidade e como esta é afetada pela penetração do vento.A etapa seguinte apresenta a modelagem de WDPS com baixa, média e alta penetração, incluindo a integração com ESS. Sobre esses modelos são então executadas simulações buscando determinar o consumo de diesel de cada um. As simulações são feitas usando a ferramenta reMIND.A última etapa é um estudo comparativo para determinar qual tecnologia de ESS é a mais apropriada para WDPS, levando-se em conta sua localização geográfica e capacidade. Uma vez que a escolha tenha sido feita, a viabilidade econômica do ESS é calculada baseado na ecomonia de combustível obtida na etepa anterior.Como esta tese apresenta uma demonstração, não foram utilizados dados reais de variação do vento nem de consumo. A variação do vento foi obtida de uma distribuição Weibull típica, que é a distribuição que mais se aproxima da característica do vento coletada em logo prazo. A variação do vento no tempo foi gerada aleatoriamente baseada nessa distribuição. A curva de consumo é baseada em curvas de consumo residenciais típicas. Embora a curva de consumo tenha sido gerada aleatoriamente, o seu formato foi mantido em conformidade com as curvas típicas.Essa tese demonstrou que ESS integrado à WDPS pode trazer uma economia razoável. Mesmo usando uma distribuição de vento com baixo valor médio (5.3 m/s), a economia obtida foi de 17%.Dentre as tecnologias de ESS pesquisadas, apenas o sistema de armazenamento com bateria (BESS na sigla em Inglês) se mostrou viável para um WDPS com pequena capacidade. Dentre as quatro tecnologias de BESS pesquisadas, Chumbo-Ácido foi a que apresentou a maior economia de diesel com o menor investimento inicial e com o menor tempo de retorno do investimento.
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Estudo das características elétricas e microestruturais de supercapacitores para armazenamento de energia / Study of electrical and microstructural characteristics of supercapacitors for energy storageFERNANDEZ, ANTONIO P.R. 11 November 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-11-11T16:52:08Z
No. of bitstreams: 0 / Made available in DSpace on 2016-11-11T16:52:08Z (GMT). No. of bitstreams: 0 / Esta dissertação tem por objetivo reportar dados relativos às características elétricas e microestruturais de eletrodos aplicadas em dispositivos armazenadores de energia, especificamente supercapacitores constituídos por eletrodos de carvão ativado. Os parâmetros elétricos estudados foram a resistência em série equivalente obtida pelo método da interrupção de corrente (ESR(Inst)) (sendo que a sigla ESR é oriunda do termo inglês Equivalent Series Resistance), a resistência em paralelo equivalente (EPR(Dep)) obtida pelo método do valor dependente (sendo que a sigla EPR é oriunda do termo inglês Equivalent Parallel Resistance) e a capacitância (C(DC)) obtida pelo método da corrente contínua (sendo que a sigla DC oriunda do termo inglês Direct Current). Tais parâmetros foram escolhidos devido ao impacto que causam no tempo de vida útil, na capacidade de armazenamento de cargas elétricas, na velocidade de carga e descarga, na perda por efeito termoiônico nos processos de carga e descarga e na perda de cargas armazenadas devido à autodescarga em supercapacitores. Os dados microestruturais reportam por meio de imagens a homogeneidade da porosidade e por meio de valores correlacionados a composição química e eventuais contaminações presentes nos eletrodos. Os dados e valores coletados possuem a intenção de servir como referência comparativa de qualidade e apontar qual parâmetro afeta mais a qualidade do supercapacitor. Para tanto foram realizados testes a fim de coletar valores de C(DC), ESR(Inst) e EPR(Dep) após a exposição de supercapacitores de 1F/5,5V a temperaturas de 50ºC, 75ºC, 100ºC e 125ºC por 672 horas, sendo os dados coletados ao inicio dos testes, à temperatura ambiente, e posteriormente a cada 168 horas. Feitos os experimentos concluiu-se que o parâmetro que sofreu maior deterioração com o acréscimo de energia térmica foi a EPR(Dep), em seguida a C(DC), que de fato pouco sofreu alteração e a ESR(Inst), em que a mudança dentro do erro de medição foi imperceptível. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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An Examination of Metal Hydrides and Phase-Change Materials for Year-Round Variable-Temperature Energy Storage in Building Heating and Cooling SystemsPatrick E Krane (12378958) 20 April 2022 (has links)
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<p>Thermal energy storage (TES) is used to reduce the operating costs of heating, ventilation, and air conditioning (HVAC) systems by shifting loads away from on-peak periods, to reduce the maximum heating or cooling capacity needed from the HVAC system, and to store excess energy generated by on-site solar power. The most commonly-used form of TES is ice storage with air conditioning (A/C) systems in commercial buildings. There has been extensive research into many other forms of TES for use with HVAC systems, both in commercial and residential buildings. However, this research is often limited to use with either heating or cooling systems.</p>
<p>Year-round, high-density storage for both heating and cooling would yield significantly larger cost savings than existing TES systems, particularly for residential buildings, where heating loads are often larger than cooling loads. This dissertation examines the feasibility of using metal hydrides for year-round storage, as well as analyzing the potential of variable-temperature energy storage for optimizing system performance beyond allowing for year-round use.</p>
<p>Metal hydrides are metals that exothermically absorb and endothermically desorb hydrogen. Since the temperature this reaction occurs at depends on the hydrogen pressure, hydrides can be used for energy storage at varying temperatures. System architecture for using metal hydrides with an HVAC system is developed. A thermodynamic model which combines a dynamic model of the hydride reactors with a static model of the HVAC system is used to calculate operating costs, compared to a conventional HVAC system, for different utility rates and locations. The payback period of the system is unacceptably high, due to the high initial cost of metal hydrides and the operating costs of compressing hydrogen to move it between hydride reactors.</p>
<p>In addition to the metal hydride system model, a generalized model of a variable-temperature TES system is used to determine the potential cost savings from dynamically altering the storage temperature to achieve optimal cost savings. Dynamic tuning does result in cost savings but is most effective for storage tank sizes significantly smaller than the optimal tank size. An alternate system design where the storage tank is charged with the outlet flow from the house achieves larger cost savings even for the optimally-sized tanks. Payback periods calculated for optimal sizing show that year-round storage has a lower payback period than separate cold and heat storage if the year-round storage system is not more expensive than two separate storage tanks. </p>
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Carbon nanotubes for adhesive, interconnect, and energy storage applicationsChen, Bingan January 2014 (has links)
No description available.
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Desktop systems for manufacturing carbon nanotube films by chemical vapor depositionKuhn, David S. 06 1900 (has links)
CIVINS / Carbon nanotubes (CNTs) exhibit exceptional electrical, thermal, and mechanical properties that could potentially transform such diverse fields as composites, electronics, cooling, energy storage, and biological sensing. For the United States Navy, composites potentially provide a significant decrease in lifetime maintenance costs of ships by eliminating hull corrosion. A stronger composite could also improve naval ship survivability or increase combat payloads by reducing the hull weight of ships and submarines. Further, cooling requirements of ship borne electronics have grown exponentially and represent a significant weight penalty for advanced ship designs. Any improvement in thermal transport could significantly improve future naval ship designs. In order to realize these benefits, methods must be discovered to fully characterize CNT growth mechanisms, consistently produce CUTs in manufacturable quantities, and to integrate CUTs into macroscale structures which reflect the properties of individual CUTs. While growth of CNTs in laboratory scale chemical vapor deposition (CVD) tube furnaces has shown great promise, existing low cost tube furnace designs limit the researcher's ability to fully separate critical reaction parameter such as temperature and flow profiles and limit the rate of temperature change during the growth process. Conventional tube furnace designs also provide limited mechanical access to the growth Site and prevent optical monitoring of the growth site, removing the ability to observe and interact in situ during growth. This thesis presents the SabreTube, a low-cost desktop cvD apparatus that decouples temperature and flow variables, provides mechanical and optical access to the reaction site during growth, and provides modular fixturing to enable versatile experimentation with and characterization of CUT growth mechanisms. This thesis also presents the Nanosled, a device designed to translate a substrate through a CVD furnace. / Contract number: N62271-97-G-0026. / CIVINS
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Novel Concept for High Dielectric Constant Composite Electrolyte DielectricsFromille, Samuel S., IV 09 1900 (has links)
Approved for public release / This research was part of an ongoing program studying the concept of multi-material dielectrics (MMD) with dielectric constants much higher than homogenous materials. MMD described in this study have dielectric constants six orders of magnitude greater than the best single materials. This is achieved by mixing conductive particles with an insulating surface layer into a composite matrix phase composed of high surface area ceramic powder and aqueous electrolyte. Specifically examined in this study was micron-scale nickel powder treated in hydrogen peroxide (H2O2) loaded into high surface area alumina powder and aqueous boric acid solution. This new class of dielectric, composite electrolyte dielectrics (CED), is employed in an electrostatic capacitor configuration and demonstrated dielectric constant of order 10 [raised to the 10th power] at approximately 1 Volt.
Additionally, it is demonstrated that treated nickel can be loaded in high volume fractions in the CED configuration. Prior studies of composite capacitors indicated a general limitation due to shorting. This results from the onset of percolation due to excess loading of conductive phases. Insulated particles described herein are successfully loaded up to 40% by volume, far above typical percolation thresholds. Simple models are presented to explain results. / Lieutenant, United States Navy
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Preparation of Electroactive Materials for High Performance Lithium-Sulfur BatteriesDirlam, Philip Thomas, Dirlam, Philip Thomas January 2016 (has links)
This dissertation is comprised of five chapters detailing advances in the synthesis and preparation of polymers and materials and the application of these materials in lithium-sulfur batteries for next-generation energy storage technology. The research described herein discusses progress towards overcoming three critical challenges presented for optimizing Li-S battery performance, specifically, addressing the highly electrically insulating nature of elemental sulfur, extending the cycling lifetime of Li-S batteries, and enhancing the charge discharge rate capability of Li-S cathodes. The first chapter is a review highlighting the use of polymers in conventional lithium-sulfur battery cathodes. Li-S battery technology presents a grand opportunity to realize an electrochemical energy storage system with high enough capacity and energy density capable of addressing the needs presented by electrical vehicles and base load storage. Polymers are ubiquitous throughout conventional Li-S batteries and their use has been critical in overcoming the challenges presented for optimizing Li-S cathode performance towards practical implementation. The high electrical resistivity of elemental sulfur requires the incorporation of conductive additives in order to formulate it into a functional cathode. A polymer binder must be utilized to integrate the elemental sulfur as the active material with the conductive additives into an electrically conductive composite affixed to a current collector. The electrochemical action of the Li-S battery results in the electroactive sulfur species converting between high and low order lithium polysulfides as the battery is discharged and charged. These lithium polysulfides become soluble at various stages throughout this cycling process that lead to a host of complications including the loss of electroactive material and slow rate capabilities. The use of polymer coatings applied to both the electroactive material and the cathode as a whole have been successful in mitigating the dissolution of lithium polysulfides by confining the redox reactions to the cathode. Elemental sulfur is largely intractable in conventional solvents and suffers from poor chemical compatibility limiting synthetic modification. By incorporating S-S bonds into copolymeric materials the electrochemical reactivity of elemental sulfur can be maintained and allow these polymers to function as the electroactive cathode materials while enabling improved processability and properties via the comonomeric inclusions. The use of inverse vulcanization, which is the direct copolymerization of elemental sulfur, is highlighted as a facile method to prepare polymeric materials with a high content of S-S bonds for use as active cathode materials. The second chapter focuses on the synthesis and polymerization of a novel bifunctional monomer containing both a styrenic group to access free radical polymerization and a propylenedioxythiophene (ProDOT) to install conductive polymer pathways upon an orthogonal oxidative polymerization. The styrenic ProDOT monomer (ProDOT-Sty) was successfully applied to a two-step sequential polymerization where the styrenic group was first leveraged in a controlled radical polymerization (CRP) to afford well defined linear homo- and block polymer precursors with pendant electropolymerizable ProDOT moieties. Subsequent treatment of the these linear polymer precursors with an oxidant in solution enabled the oxidative polymerization of the pendant ProDOT groups to install conductive polythiophene inclusions. Although the synthesis and CRP of ProDOT-Sty was novel, the key advance in this work was successful demonstration that sequential radical and oxidative polymerizations could be carried out to install conductive polymer pathways through an otherwise nonconductive polymer matrix. The third chapter expands upon the use of ProDOT-Sty to install conductive polymer pathways through a sulfur copolymer matrix. The highly electrically insulating nature of elemental sulfur precludes its direct use as a cathode in Li-S batteries and thus the use of ProDOT-Sty in the preparation of a high sulfur content copolymer with conductive inclusions was targeted to improve electrical properties. Inverse vulcanization of elemental sulfur with ProDOT-Sty and a minimal amount of 1,3-diisopropenylbenzene (DIB) was first completed to afford a sulfur rich copolymer with electropolymerizable side chains. Subsequently, the improved processability of the sulfur copolymer was exploited to prepare thin polymer films on electrode surfaces. The poly(ProDOT-Sty-𝑐𝑜-DIB-𝑐𝑜-sulfur) (ProDIBS) films were then subjected to oxidizing conditions via an electrochemical cell to invoke electropolymerization of the ProDOT inclusions and install conductive poly(ProDOT) pathways. Evaluation of the electrical properties with electrochemical impedance spectroscopy (EIS) revealed that the charge transfer resistance was reduced from 148 kΩ to 0.4 kΩ upon installation of the conductive poly(ProDOT) corresponding to an improvement in charge conductance of more than 95%. This also represented a key advance in expanding the scope of the inverse vulcanization methodology as the first example of utilizing a comonomer with a functional side chain. The fourth chapter focuses on expanding the scope of the inverse vulcanization polymerization methodology to include aryl alkyne based comonomers and the application of new these new sulfur copolymers as active cathode materials in Li-S batteries. The early work on developing inverse vulcanization relied heavily on the use of DIB as one of the few comonomers amenable to bulk copolymerization with elemental sulfur. One of the principal limitations in comonomer selection for inverse vulcanization is the solubility of the comonomer in molten sulfur. Generally it has been observed that aromatic compounds with minimal polarity are miscible and thus common classes of comonomers such as acrylates and methacrylates are immiscible and preclude their compatibility with inverse vulcanization. It was found that aryl alkynes are a unique class of compounds that are both miscible with molten sulfur and provide reactivity with sulfur centered radicals through the unsaturated carbon-carbon triple bonds. Additionally, it was found that internal alkynes were best suited for inverse vulcanization to preclude abstraction of the somewhat acidic hydrogen from terminal alkynes. 1,4-Diphenylbutadiyne (DiPhDY) was selected as a prototypical comonomer of this class of compounds for preparing high sulfur content copolymers via inverse vulcanization. Poly(sulfur-𝑐𝑜-DiPhDY) was prepared with various compositions of S:DiPhDY and these copolymers were formulated into cathodes for electrochemical testing in Li-S batteries. The poly(S-𝑐𝑜-DiPhDY) based cathodes exhibited the best performance reported at the time for a polymeric cathode material with the figure of merit of the first inverse vulcanizate to enable a cycle lifetime of up to 1000 cycles. The fifth chapter details the preparation of composite materials composed of a sulfur or copolymeric sulfur matrix with molybdenum disulfide (MoS₂) inclusions and the use of these materials for Li-S cathodes with rapid charge/discharge rate capabilities. The higher order lithium polysulfide redox products (e.g., Li₂S₈ Li₂S₆) generated during Li-S cycling are soluble in the electrolyte solution of the battery. The rate capability of the Li-S battery is thus fundamentally limited by mass transfer as these electroactive species must diffuse back to the cathode surface in order to undergo further reduction (discharge) or oxidation (charge). In order to limit the effective diffusion length of the soluble lithium polysulfides and therefore mitigate the diffusion limited rate, composite materials with fillers capable of binding the lithium sulfides were prepared. MoS₂ was selected as the filler as simulations had indicated lithium polysulfide had a strong binding interaction with the surface of MoS₂. Furthermore, it was demonstrated for the first time that metal chalcogenides such as MoS₂ readily disperse in molten sulfur which enabled the facile preparation of the composite materials in situ. The composites were prepared by first dispersing MoS₂ in liquid sulfur or a solution of liquid sulfur and DIB below the floor temperature of S₈ (i.e.<160 °C). The dispersions were then heated above the floor temperature of S₈ to induce ring opening polymerization of the sulfur phase and afford the composites. The composites were found to be potent active cathode materials in Li-S batteries enabling extended cycle lifetimes of up to 1000 cycles with excellent capacity retention. Furthermore, the composite materials were successful in enhancing the rate capability of the Li-S cathodes where reversible capacity of >500 mAh/g was achieved at the rapid rate of 5C (i.e. a 12 min. charge or discharge time).
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Active power control response from large offshore wind farmsBanham-Hall, Dominic January 2012 (has links)
The GB power system will see huge growth in transmission connected wind farms over the next decade, driven by European clean energy targets. The majority of the UK’s wind development is likely to be offshore and many of these wind farms will be interfaced to the grid through power converters. This will lead to a loss of intrinsic inertia and an increasing challenge for the system operator to keep grid frequency stable. Given this challenge, there is increasing interest in understanding the capabilities of converter control systems to provide a synthesised response to grid transients. It is interesting to consider whether this response should be demanded of wind turbines, with a consequential reduction in their output, or if advanced energy storage can provide a viable solution. In order to investigate how large offshore wind farms could contribute to securing the power system, wind turbine and wind farm models have been developed. These have been used to design a patented method of protecting permanent magnet generator’s converters under grid faults. Furthermore, these models have enabled investigation of methods by which a wind turbine can provide inertial and frequency response. Conventionally inertial response relies on the derivative of a filtered measurement of system frequency; this introduces either noise, delay or both. This research proposes alternative methods, without these shortcomings, which are shown to have fast response. Overall, wind farms are shown to be technically capable of providing both high and low frequency response; however, holding reserves for low frequency response inevitably requires spilling wind. Wind’s intermittency and full output operation are in tension with the need of the power system for reliable frequency response reserves. This means that whilst wind farms can meet the technical requirements to hold reserves, they bid uncompetitive prices in the market. This research shows that frequency response market prices are likely to rise in future suggesting that the Vanadium Redox Flow Battery is one technology which could enter this market and also complement wind power. Novel control incorporating fuzzy logic to manage the battery is developed to allow a hybrid wind and storage system to aggregate the benefits of frequency response and daily price arbitrage. However, the research finds that the costs of smoothing wind power output are a burden on the store’s revenue, leading to a method of optimising the combined response from an energy store and generator that is the subject of a patent application. Furthermore, whilst positive present value may be derived from this application, the long payback periods do not represent attractive investments without a small storage subsidy.
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Emergency thermal energy storage: cost & energy analysisBembry, Walter T., IV January 1900 (has links)
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.
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