The continuous escalation of intermittent energy added to the grid and forecasts of peaking power demand increments are rising the effort spent for evaluating the economic feasibility of energy storages. The aim of this research is the techno-economic analysis of Compressed Air Energy Storage (CAES) systems, capable of storing large quantities of off-peak electric energy in the form of high-pressure air, as an ―energy stock‖ which allows the production of high-profit on-peak electricity when required by the grid. Several studies of both conventional and innovative adiabatic concepts are carried out in order to identify and improve the parameters that mostly affect the plant performances. Technical models, that consider the effect of time, are developed to evaluate the parameters that reduce the electric energy spent for compressing the air and that maximize the electric energy produced. In the conventional plant, particular attention is put on the understanding of the effects of air storage pressure range, recuperator, reheating and Turbine Inlet Temperature. For the adiabatic instead, a thorough analysis of the challenging Thermal Energy Storage (TES) is performed for understanding the advantages and drawbacks of this novel efficient concept of CAES. In a further step the economic analyses are aimed at evaluating the different configurations proposed in the technical investigation and the effects that variations of generation train and storage characteristics have on the profitability. After an analysis of the TES impact on the profits, a final comparison is carried out against two existing technologies: Pumped Hydro Energy Storage and gas turbine. The results of these studies confirm, from a technical and economic point of view, the reasons of the growing interest toward CAES as a feasible solution to manage the intermittent energy production. In particular they underline the conventional CAES as promising technology to undertake.

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In order to increase the efficiency of an adsorption heat pump system, a stratified thermal heat storage can be used to enable regeneration of heat between the different phases of the process. It’s crucial to avoid mixing and to keep layers intact inside the storage tank. As mixing generally occurs during charging and discharging, the aim of this project is minimizing these effects by introducing porous media into the region of the inlet ports. The impact of porous media on laminar and turbulent flow inside stratified thermal storage tanks is qualitatively and quantitatively investigated. Two thermal storage tanks are examined in which polyurethane foam is used as porous medium. Numerical results are compared with experimental results in order to study the effects of the porous medium and validating numerical models. For the quantitative investigation, equations describing flow in porous media are obtained and implemented into computational fluid dynamics (CFD) models. Simulations of storage tanks are performed by means of 2D-axisymmetric domain models. Tanks are investigated qualitatively using two methods; background oriented schlieren (BOS) and ink colored inlet water, in order to visualize flow and mixing inside tanks. Thermo elements are also used to measure temperatures at given locations. Results from experimental- and numerical cases show how porous media influence stratification in a positive way. Flow visualizing experiments (using ink and BOS) showed decrease in thermocline thickness when using polyurethane foam. This could also be seen for the numerical cases. Experimental- and numerical investigations of the ability of porous media to damp turbulence intensity and kinetic energy, showed a positive effect. Further improvements have to be done, adjusting numerical models to experimental results. Comparison between the numerical- and experimental results showed differences both in flow fields and temperature distributions. Results indicate however, that porous media could play an increasing role in the development of stratified heat storages. / Stratifierade värmelagringstankar kan användas för att öka effektiviteten hos adsorptionsvärmepumpsprocesser genom att möjliggöra regeneration av värme mellan faserna. För att dessa effektivt ska kunna användas är det viktigt att temperaturskikt hålls intakta inuti lagringstankarna och att omröring undviks. Då omröring oftast uppstår vid laddning och tömning av lagringstankarna är målet för det här projektet att minska denna effekt genom att använda porösa medier vid deras inlopp. Porösa mediers inverkan på flöden och temperaturskikt inuti värmelagringstankar undersöks både kvalitativt och kvantitativt i det här projektet. Två tankar undersöks där polyuretanskum används som poröst medium. Numeriska resultat jämförs med experimentella för att undersöka effekterna av de porösa medierna, samt för att validera de numeriska modeller som används. Ekvationer som beskriver flödet genom porösa medier implementeras i CFD (computational fluid dynamics) modeller och lagringstankarna modelleras som 2D-axelsymmetriska domäner. Bakgrundsorienterad schlierenteknik (BOS) och färgning av inloppsvatten används för den kvalitativa undersökningen och termoelement används för att mäta temperaturer vid olika positioner. Numeriska och experimentella resultat visar hur porösa medier har en positiv inverkan på temperaturskiktningen. Resultat från experiment då BOS teknik och färgning av vatten används visar en minskning av det termoklina skiktets tjocklek med en ökad polyuretanskumtjocklek. Detta kunde också ses för de numeriska fallen. Numeriska och experimentella resultat visar även att porösa medier har en positiv inverkan på dämpningen av turbulens och kinetisk energi. Fortsatt arbete krävs för att anpassa numeriska modeller till experimentella data. Jämförelser mellan numeriska och experimentella resultat uppvisar skillnader både hos flödesfält samt hos temperaturfördelningar inuti tankarna. Resultaten visar dock att porösa medier skulle kunna spela en betydande roll för utvecklingen av stratifierade värmelagringstankar.

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Yes / The process of capturing and storing carbon dioxide (CCS) was previously considered a crucial and time-sensitive approach for diminishing CO2 emissions originating from coal, oil, and gas sectors. Its implementation was seen necessary to address the detrimental effects of CO2 on the atmosphere and the ecosystem. This recognition was achieved by previous substantial study efforts. The carbon capture and storage (CCS) cycle concludes with the final stage of CO2 storage. This stage involves primarily the adsorption of CO2 in the ocean and the injection of CO2 into subsurface reservoir formations. Additionally, the process of CO2 reactivity with minerals in the reservoir formations leads to the formation of limestone through injectivities. Carbon capture and storage (CCS) is the final phase in the CCS cycle, mostly achieved by the use of marine and underground geological sequestration methods, along with mineral carbonation techniques. The introduction of supercritical CO2 into geological formations has the potential to alter the prevailing physical and chemical characteristics of the subsurface environment. This process can lead to modifications in the pore fluid pressure, temperature conditions, chemical reactivity, and stress distribution within the reservoir rock. The objective of this study is to enhance our existing understanding of CO2 injection and storage systems, with a specific focus on CO2 storage techniques and the associated issues faced during their implementation. Additionally, this research examines strategies for mitigating important uncertainties in carbon capture and storage (CCS) practises. Carbon capture and storage (CCS) facilities can be considered as integrated systems. However, in scientific research, these storage systems are often divided based on the physical and spatial scales relevant to the investigations. Utilising the chosen system as a boundary condition is a highly effective method for segregating the physics in a diverse range of physical applications. Regrettably, the used separation technique fails to effectively depict the behaviour of the broader significant system in the context of water and gas movement within porous media. The limited efficacy of the technique in capturing the behaviour of the broader relevant system can be attributed to the intricate nature of geological subsurface systems. As a result, various carbon capture and storage (CCS) technologies have emerged, each with distinct applications, associated prices, and social and environmental implications. The results of this study have the potential to enhance comprehension regarding the selection of an appropriate carbon capture and storage (CCS) application method. Moreover, these findings can contribute to the optimisation of greenhouse gas emissions and their associated environmental consequences. By promoting process sustainability, this research can address critical challenges related to global climate change, which are currently of utmost importance to humanity. Despite the significant advancements in this technology over the past decade, various concerns and ambiguities have been highlighted. Considerable emphasis was placed on the fundamental discoveries made in practical programmes related to the storage of CO2 thus far. The study has provided evidence that despite the extensive research and implementation of several CCS technologies thus far, the process of selecting an appropriate and widely accepted CCS technology remains challenging due to considerations related to its technological feasibility, economic viability, and societal and environmental acceptance.

Yes / Capturing and storing CO2 (CCS) was once regarded as a significant, urgent, and necessary option for reducing the emissions of CO2 from coal and oil and gas industries and mitigating the serious impacts of CO2 on the atmosphere and the environment. This recognition came about as a result of extensive research conducted in the past. The CCS cycle comes to a close with the last phase of CO2 storage, which is accomplished primarily by the adsorption of CO2 in the ocean and injection of CO2 subsurface reservoir formation, in addition to the formation of limestone via the process of CO2 reactivity with reservoir formation minerals through injectivities. CCS is the last stage in the carbon capture and storage (CCS) cycle and is accomplished chiefly via oceanic and subterranean geological sequestration, as well as mineral carbonation. The injection of supercritical CO2 into geological formations disrupts the sub-surface’s existing physical and chemical conditions; changes can occur in the pore fluid pressure, temperature state, chemical reactivity, and stress distribution of the reservoir rock. This paper aims at advancing our current knowledge in CO2 injection and storage systems, particularly CO2 storage methods and the challenges encountered during the implementation of each method and analyses on how key uncertainties in CCS can be reduced. CCS sites are essentially unified systems; yet, given the scientific context, these storage systems are typically split during scientific investigations based on the physics and spatial scales involved. Separating the physics by using the chosen system as a boundary condition is a strategy that works effectively for a wide variety of physical applications. Unfortunately, the separation technique does not accurately capture the behaviour of the larger important system in the case of water and gas flow in porous media. This is due to the complexity of geological subsurface systems, which prevents the approach from being able to effectively capture the behaviour of the larger relevant system. This consequently gives rise to different CCS technology with different applications, costs and social and environmental impacts. The findings of this study can help improve the ability to select a suitable CCS application method and can further improve the efficiency of greenhouse gas emissions and their environmental impact, promoting the process sustainability and helping to tackle some of the most important issues that human being is currently accounting global climate change. Though this technology has already had large-scale development for the last decade, some issues and uncertainties are identified. Special attention was focused on the basic findings achieved in CO2 storage operational projects to date. The study has demonstrated that though a number of CCS technologies have been researched and implemented to date, choosing a suitable and acceptable CCS technology is still daunting in terms of its technological application, cost effectiveness and socio-environmental acceptance.

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In an effort to mitigate carbon dioxide (CO2) emissions in the atmosphere, the Southeast Offshore Storage Resource Assessment (SOSRA) project has for objective to identify geological targets for CO2 storage in two main areas: the eastern part of the Gulf of Mexico and the Atlantic Ocean subsurface. SOSRA's second objective is to estimate the geological targets' capacity to store up to 30 million metric tons of CO2 each year with an error margin of ±30%. As part of this project, the research presented here focuses on the outer continental shelf of North Carolina and its potential for the deployment of large-scale offshore carbon storage in the near future. To identify geological targets, workflow followed typical early oil and gas exploration protocols: collecting existing datasets, selecting the most applicable datasets for reservoir exploration, and interpreting datasets to build a comprehensive regional geological framework of the subsurface of the outer continental shelf. The geomodel obtained can then be used to conduct static volumetric calculations estimating the storage capacity of each identified target. Numerous uncertainties regarding the geomodel were attributed to the variable coverage and quality of the geological and geophysical data. To address these uncertainties and quantify their potential impact on the storage capacity estimations, dynamic volumetric calculations (reservoir simulations) were conducted. Results have shown that, in this area, both Upper and Lower Cretaceous Formations have the potential to store large amounts of CO2 (in the gigatons range). However, sensitivity analysis highlighted the need to collect more data to refine the geomodel and thereby reduce the uncertainties related to the presence, dimensions and characteristics of potential reservoirs and seals. Reducing these uncertainties could lead to more accurate storage capacity estimations. Adequate injection strategies could then be developed based on robust knowledge of this area, thus increasing the probability of success for carbon capture and storage (CCS) offshore projects in North Carolina's outer continental shelf. / Doctor of Philosophy / Since the industrial revolution, a significant increase in the anthropogenic emissions of greenhouse gases has been observed worldwide. The rise in concentration of these gases in the atmosphere, specifically carbon dioxide (CO₂), has been linked to an increase in the average temperature on Earth, what is commonly known as global warming. To mitigate the emission of anthropogenic CO₂ in the atmosphere and consequently limit its impact on Earth’s climate, Carbon Capture and Storage projects (CCS) have been developed on various scales. In this type of project, CO₂ is captured from an emitting source (e.g., power plants), then transported via pipelines and stored in deep geological formations. In the United States, onshore CCS projects have demonstrated the technical feasibility of such projects. However, controversies associated with public acceptance and mineral ownership make expansive onshore CCS project development complicated. For these reasons, the U.S. Department of Energy (DOE) has been investigating offshore locations for the deployment of large-scale CCS projects. Southeast Offshore Storage Resource Assessment (SOSRA) is a project sponsored by the U.S. DOE to assess the storage potential of the eastern part of the Gulf of Mexico and the Atlantic Ocean as a first step towards the development of large-scale offshore storage of CO₂. The state of North Carolina was identified as an adequate candidate for CO₂ offshore storage due to its location on the Atlantic coast and its elevated CO₂ emissions from the power plants on its coastal plains. However, as exploration conducted on the outer continental shelf of North Carolina has been minimal, published information regarding the subsurface of this area remains limited to this date. To ensure the safe, long-term storage of CO₂ in this area, an extensive study was needed to select suitable geological formations and determine the storage capacity of each identified target. The research described here aimed to identify such geological targets and estimate the CO₂ storage capacity of North Carolina’s outer continental shelf

With continued advances in computing, the amount of digital data continues to grow at an astounding rate. This has strained enterprise infrastructures and triggered development of service oriented architectures. In recent years, storage has also begun its transformation into a class of service. By outsourcing storage to an external storage service provider (SSP), enterprises not only cut management cost but also obtain on-demand infrastructure with superior disaster recovery and content dissemination capabilities. Wide deployment of this new outsourced storage environment requires solutions to many challenging problems. The foremost is the development of usable security and access control mechanisms that provide desirable levels of data confidentiality without placing an inordinate amount of trust into the SSP. This absence of a trusted reference monitor is a fundamental departure from traditional mechanisms and new solutions are required. The second important challenge is the autonomic management of SSP's infrastructure, uniquely characterized by a highly dynamic workload with large data capacity requirements. This dissertation research proposes models and techniques to address these two challenges. First, we introduce a novel access control system called xACCESS that uses cryptographic access control primitives (CAPs) to "embed" access control into stored data. This eliminates any dependency on the SSP for enforcement of security policies. We also analyze the privacy characteristics of its data sharing mechanisms and propose enhancements for more secure and convenient data sharing. We also develop a secure multiuser search approach that permits hosting of secured search indices at untrusted SSPs. We introduce a novel access control barrel (ACB) primitive that embeds access control into indices to prevent unauthorized information extraction during search. Our contribution to the autonomic SSP storage management has two important highlights. First, we have developed an impact analysis engine that efficiently analyzes the impact of a client-initiated change (workload surge, storage growth) on the SSP storage area network with minimal administrator involvement. Second, we have designed a new algorithm to quickly perform reallocation of resources in order to efficiently integrate the client change.

<p dir="ltr">Ice thermal energy storage (ITES) systems have long been an economic way to slash cooling costs in the commercial sector since the 1980s. An ITES system generates cooling in the formation of ice within a storage tank. This occurs during periods of the day when the cost of electricity is low, normally at night. This ice is then melted to absorb the energy within the conditioned space. While ITES systems have been prosperous in the commercial sector, they have yet to take root in the residential sector.</p><p dir="ltr">The U.S. Department of Energy (DoE) has published guidelines for TES. The DoE guidelines include providing a minimum of four hours of cooling, shifting 30-50% of a space’s cooling load to non-peak hours, minimizing the weight, volume, complexity, and cost of the system, creating a system than operates for over 10,000 cycles, enacting predictive control measures, and being modular to increase scale for larger single-family and multi-family homes [1]. The purpose of this research is to develop a model that meets these guidelines.</p><p dir="ltr">After extensive research in both experimental data, technical specifications, existing models, and best practices taken from the works of others a MATLAB model was generated. The modeled ITES system is comprised of a 1m diameter tank by 1m tall. Ice was selected as the PCM. A baseline model was constructed with parameters deemed to be ideal. This model generated an ITES system that can be charged in under four hours and is capable of providing a total of 22.18 kWh of cooling for a single-family home over a four-hour time period. This model was then validated with experimental data and found to have a root mean squared error of 0.0959 for the system state of charge. During the validation both the experimental and model estimation for the water/ice within the tank converged at the HTF supply temperature of -5.2°C.</p><p dir="ltr">With the model established, a parametric analysis was conducted to learn how adjusting a few of the system parameters impact it. The first parameter, reducing the pipe radius, has the potential to lead to a 152.6-minute reduction in charge time. The second parameter, varying the heat transfer fluid (HTF) within the prescribed zone of 0.7 kg/s to 1.2 kg/s, experienced a 4.8-minute increase in charge time for the former and a decrease in charge time by 5.4 minutes for the latter. The third parameter, increasing the pipe spacing and consequently increasing the ratio of mass of water to mass of HTF, yielded a negative impact. A 7.1mm increase in pipe spacing produced a 16.6-minute increase in charge time. Meanwhile, a 14.2mm increase in pipe spacing created a 93.3-minute increase in charge time and exceeded the charging time limit of five hours.</p><p dir="ltr">This functioning model establishes the foundation of creating a residential-scale ITES system. The adjustability and scalability of the code enable it to be modified to user specifications. Thus, allowing for various prototypes to be generated based on it. The model also lays the groundwork to synthesize a code containing an ITES system and a heat pump operating as one. This will aid in the understanding of residential-scale ITES systems and their energy effects.</p>