<p>The use of renewable energy systems is ever-growing in today's electricity grid to reduce the carbon footprint on the environment. However, a problem with wind and solar renewable energy systems is availability. Wind and solar energy production are entirely dependent on the weather, whereas global electricity demands have no such limitation. A cost-effective solution to the energy availability problem is to incorporate energy storage systems. The Economic Long-Duration Electricity Storage by Using Low-Cost Thermal Energy Storage and High-Efficiency Power Cycle (ENDURING) system developed at the National Renewable Energy Laboratory (NREL) is a potential  energy storage system. In the ENDURING system, particles are heated via renewable energy or off-peak grid electricity and stored in large silos. When the electricity needs to be regenerated, the hot particles are passed to a Pressurized Fluidized Bed Heat Exchanger (PFB-HX), which heats air, and the hot pressurized air flows to a turbine and generator to produce electricity. The focus of this dissertation is on two components within the ENDURING system: the particle heater and the PFB-HX.</p> <p>First, the heat transfer within the particle heater is investigated numerically via Computational Fluid Dynamics (CFD) coupled with Discrete Element Modeling (DEM). Although heat transfer to traditional molecular fluids such as liquids and gases are well characterized, the heat transfer to flowing particles is less understood. The heater surface angle, particle-particle and particle-wall friction coefficients, and contact resistance are parametrically varied to discover their individual effects on the heat transfer process. A separate set of simulations is conducted to compare against an experimental particle heater built at NREL. In addition to elucidating the heat transfer performance, the simulations also reveal oscillatory flow patterns. It is discovered that such turbulent behavior is related to the geometry of the heater elements.<br> </p> <p>Second, a laboratory-scale experimental setup of the PFB-HX is built. The temperature, pressure drop, and minimum fluidization velocity are used to characterize the heat transfer and assess the capabilities of the PFB-HX. High-temperature fluidized bed experiments with an initial temperature gradient are performed. The bed becomes fluidized, but temperature gradients remain, and the bed is not fully mixed. At sufficient superficial velocity, the bed temperature becomes uniform. CFD-DEM coupled simulations are performed to investigate the temperature distributions more precisely. Initial bed temperature differences of 100, 300, and 500K are simulated with varying superficial velocities to create a regime map. The purpose of the regime map is to determine when the fluidized bed temperature becomes fully mixed for different initial conditions and gas velocities. The overall goal of this work is to understand the heat transfer processes of the flowing particles in both the particle heater and the PFB-HX to aid in the design of the ENDURING system.</p>

The use of electricity from Distributed Energy Resources like wind and solar powerwill impact the performance of the electricity network and this sets a limit to theamount of such renewables that can be connected. Investment in energy storage andcommunication technologies enables more renewables by operating the networkcloser to its limits. Electricity networks using such novel techniques are referred toas “Smart Grids”. Under favourable conditions the use of these techniques is analternative to traditional network planning like replacement of transformers orconstruction of new power line.The Hosting Capacity is an objective metric to determine the limit of an electricitynetwork to integrate new consumption or production. The goal is to create greatercomparability and transparency, thereby improving the factual base of discussionsbetween network operators and owners of Distributed Energy Resources on thequantity and type of generation that can be connected to a network. This thesisextends the Hosting Capacity method to the application of storage and curtailmentand develops additional metrics such as the Hosting Capacity Coefficient.The research shows how the different intermittency of renewables and consumptionaffect the Hosting Capacity. Several case studies using real production andconsumption measurements are presented. Focus is on how the permitted amountof renewables can be extended by means of storage, curtailment and advanceddistributed protection and control schemes. / Användningen av el från förnyelsebara energikällor som vind och sol kommer att påverka elnätet, som sätter en gräns för hur mycket distribuerad energiproduktion som kan anslutas. Investeringar i storskalig energilager och användning av modern kommunikationsteknologi gör det möjligt att öka andelen förnyelsebarenergi genom att nätet kan drivas närmare sina gränser. Elnät med sådana nya tekniker kallas ofta för ”Smarta Elnät". Implementering av sådana smarta elnät kan vara ett alternativ till traditionell nätplanering och åtgärder som utbyte av transformatorer eller konstruktion av nya kraftledningen.Nätets acceptansgräns är ett objektivt mått för att bestämma gränsen för nätets förmåga att integrera ny förbrukning eller produktion. Målet är att skapa större transparens och bidra till ett bättre faktaunderlag i diskussioner mellan nätoperatörer och ägare av distribuerade energiresurser. Denna avhandling utökar acceptansgränsmetoden för tillämpning med energilager och produktions nedstyrning och utvecklar ytterligare begrepp så som acceptansgränsen koefficienten.Forskningen visar hur varierbarheten hos olika förnyelsebara energikällor samverkar med förbrukningen och påverkar nätets acceptansgräns. Flera fallstudier från verkliga elnät och med uppmätt produktion och konsumtion presenteras. Fokus är på hur den tillåtna mängden förnyelsebara energikällor kan ökas med hjälp av energilagring, kontrollerad produktionsnedstyrning och med avancerad distribuerade skydd och kontroll applikationer. / Nicholas Etherden works at STRI AB (www.stri.se) in Gothenburg, Sweden. When he is not pursuing his half-time PhD studies he works as a specialist consultant in the field of Power Utility Automation, specialising on the IEC 61850 standard for power utility automation (today widely used in substations as well as some wind parks, hydro plants and DER and Smart Grid applications such as vehicle-to-grid integration). The author of this thesis received his Master of Science in Engineering Physics from Uppsala University 2000. Side tracks during his engineering studies included studies in theoretical philosophy, chemistry, ecology and environmental sciences as well as chairing the Swedish student committee of the Pugwash Conferences on Science and Worlds Affairs and later board member of the International Network of Engineers and of Scientists for Global Responsibility (INES) and chair of Swedish Scientists and Engineers Against Nuclear Arms. He has been a trainee at ABB in Västerås Sweden and spent six years as developer and team leader for the application development of a new relay protection family (ABB IED 670 series). In parallel to his professional work he studied power system engineering at Mälardalens University and travelled to all continents of the world. Since 2008 he is responsible for the STRI IEC 61850 Independent Interoperability Laboratory and a member of IEC Technical Committee 57 working group 10 "Power system communication and associated data models” and UCA/IEC 61850 User group testing subcommittee. He is co-author of IEC 61850-1 and main contributor to “Technical Report on Functional Test of IEC 61850 systems” and has held over 25 hands-on courses around the world on IEC 61850 “Communication networks and systems for power utility automation”. / SmartGrid Energilager

<p dir="ltr">Catalyzing a green hydrogen economy can accelerate progress towards achieving the goal of a sustainable energy map with net-zero carbon emissions by rapid strides. An environmentally benign electrochemical energy conversion system is the Polymer Electrolyte Fuel Cell (PEFC) which uses hydrogen as a fuel to produce electricity and is notably used in a variety of markets such as industries, commercial setups, and across the transportation sector, and is gaining prominence for use in heavy-duty vehicles such as buses and trucks. Despite its potential, the commercialization of PEFCs needs to address several challenges which are manifested in the form of mass transport limitations and deleterious mechanisms at the interfacial scale under severe operating conditions. Achieving a robust electrochemical performance in this context is predicated on desired interactions at the triple-phase boundary of the electrochemical engine of the PEFC – the porous cathode catalyst layer (CCL) where the principal oxygen reduction reaction (ORR) takes place. The liquid water produced as a byproduct of the ORR helps minimize membrane dehydration; however, excess water renders the reaction sites inactive causing reactant starvation. In addition, the oxidation of the carbonaceous support in the electrode and loss of valuable electrochemically active surface area (ECSA) pose major barriers that need to be overcome to ameliorate the life expectancy of the PEFC.</p><p dir="ltr">In this thesis, the multimodal physicochemical interactions occurring inside the catalyst layer are investigated through a synergistic blend of visualization and computational techniques. The spatiotemporal dynamics of capillary force-driven liquid transport that ensues concentration polarization thereby affecting the desired response will be probed in detail. The drop in efficacy of the ORR due to competing catalyst aging mechanisms and the impact of degradation stressors on chemical potential-induced instability will be examined. The reaction-transport-mechanics interplay in core-shell nanoparticles, a robust class of electrocatalysts that promises better mass activity compared to the single metal counterparts is further highlighted. Finally, the influence of electrode microstructural attributes on the electrochemical performance of the reverse mode of fuel cell operation, i.e., Proton Exchange Membrane Water Electrolyzers (PEMWEs) is investigated through a mesoscale lens.</p>

<div> Porous lithium ion battery (LIB) electrodes are comprised of electrochemically active material particles that store lithium and a surrounding conductive binder, liquid electrolyte, carbon black mixture that facilitates ionic and electronic transport. Typically, lithium diffusivity is several orders of magnitude smaller in the active material as compared to the surrounding electrolyte, making the electrode microstructure a governing factor in determining the balance between its lithium storage capacity and transport rate. Here, the effects of microstructure on the performance of LIBs are systematically analyzed at three length scales - the single particle length scale, the spatially resolved multiple particle length scale, and the porous electrode layer (homogenized) length scale. At the single particle length scale, a thermodynamically consistent variational framework is presented to examine the effects of crystallographic anisotropy, crystallographic texture, grain size, and grain morphology on the LiNi_1/3Mn_1/3Co_1/3O₂ (NMC111) chemistry. The theory was extended to the spatially resolved multiple particle length scale and the porous electrode layer length scale to explain the microstructural origin of experimentally observed instances of apparent phase separation in NMC111. At the electrode length scale, a data driven framework is presented to evaluate the electrochemical performance of a wide range of particle morphologies and battery architectures. Specifically, microstructural characteristics of 53 356 microstructures are assessed, and strategies to optimize electrode design parameters such as active particle morphology, spatial orientation, electrode porosity, and cell thickness are presented.</div><p></p>

<p dir="ltr">Distributed energy resources (DERs), such as rooftop solar generation and energy storage systems, are becoming more prevalent in distribution systems. DERs are connected to the distribution system via power electronic converters, introducing faster dynamics in the system. Understanding the system dynamics under a high penetration of inverter-based DERs is critical for power system researchers and practitioners, driving the development of modeling techniques and simulation software. Aiming to reduce computational complexity, existing tools and techniques often employ various approximations. Meanwhile, modern advancements in computational hardware capabilities provide opportunities to include the faster time-scale dynamics. To address this, the primary objective of this thesis is to develop an open-source Python simulation package, Dynamic Simulation using Sparse Tableau Approach in Python, DynaSTPy (pronounced “dynasty”), capable of capturing the dynamics of all components in a distribution feeder. The distribution feeder is modeled as a system of Differential-Algebraic Equations (DAEs). Further, each component in the feeder is modeled based on the Sparse Tableau Approach (STA), which involves the representation of component model equations using sparse matrices, facilitating a systematic procedure to model the components and construct the system DAEs. In sinusoidal steady state, the DAEs can be represented in phasor form, extending the approach to perform power flow analysis of distribution feeders.</p>

<p dir="ltr">Electric aircraft offer a promising avenue for reducing aviation's environmental impact through decreased greenhouse gas emissions and noise pollution. Nonetheless, their adoption is hindered by the challenge of limited operational range. Addressed in the study is the range limitation by integrating and optimizing multiple energy storage components—hydrogen fuel cells, Li-ion batteries, and ultracapacitors—through advanced energy management strategies. Utilizing meta-heuristic optimization methods, the research assessed the dynamic performance of each energy component and the effectiveness of the energy management strategy, primarily measured by the hydrogen consumption rate. MATLAB simulations validated the proposed approach, indicating a decrease in hydrogen usage, thus enhancing efficiency and potential cost savings. Artificial Gorilla Troop Optimization yielded the best results with the lowest average hydrogen consumption rate (102.62 grams), outperforming Particle Swarm Optimization (104.68 grams) and Ant Colony Optimization (105.96 grams). The findings suggested that employing a combined energy storage and optimization strategy can significantly improve the operational efficiency and energy conservation of electric aircraft. The study highlighted the potential of such strategies to extend the range of electric aircraft, contributing to a more sustainable aviation future.</p>

<p dir="ltr">The urgent global shift towards decarbonization necessitates the development of robust frameworks to navigate the complex technological, financial, and regulatory challenges emerging in the clean energy transition. Furthermore, the increased adoption of renewable energy sources (RES) is correlated to the exponential growth in weather data research over the last few years. This circular relationship, where big data drives renewable growth, which feeds back the data pipeline, serves as the primary focus of this study: the development of computational tools across diverse spatial and temporal scales for the optimal design and operation of renewable energy-based systems. Two scales are considered, differentiated by their primary objectives and techniques used. </p><p dir="ltr"> In the first one, the integration of probabilistic forecasts into the operations of RES microgrids (MGs) is studied in detail. It is revealed that longer scheduling horizons can reduce dispatch costs but at the expense of forecast accuracy due to increased prediction accuracy decay (PAD). To address this, a novel method that determines how to split the time horizon into timeblocks to minimize dispatch costs and maximize forecast accuracy is proposed. This forms the basis of an optimal rolling horizon strategy (ORoHS) which schedules distributed energy resources over varying prediction/execution horizons. Results offer Pareto-optimal fronts, showing the trade-offs between cost and accuracy at varying confidence levels. Solar power proved more cost-effective than wind power due to lower variability, despite wind’s higher energy output. The ORoHS strategy outperformed common scheduling methods. In the case study, it achieved a cost of \$4.68 compared to \$9.89 (greedy policy) and \$9.37 (two-hour RoHS). The second study proposes the Caribbean Energy Corridor (CEC) project, a novel, ambitious initiative that aims to achieve total grid connectivity between the Caribbean islands. The analysis makes use of thorough data procedures and optimization methods for the resource assessment and design tasks needed to build such an infrastructure. Renewable energy potentials are quantified under different temporal and spatial coverages to maximize usage. Prioritizing offshore wind development, the CEC’s could significantly surpass anticipated growth in energy demand, with an estimated installed capacity of 34 GW of clean energy upon completion. The corridor is modeled as an HVDC grid with 32 nodes and 31 links. Underwater transmission is optimized with a Submarine-Cable-Dynamic-Programming (SCDP) algorithm that determines the best routes across the bathymetry of the region. It is found that the levelized cost of electricity remains on the low end at \$0.11/kWh, despite high initial capital investments. Projected savings reach \$ 100 billion when compared with ”business-as-usual” scenarios and the current social cost of carbon. Furthermore, this infrastructure has the potential to create around 50,000 jobs in construction, policy, and research within the coming decades, while simultaneously establishing a robust and sustainable energy-water nexus in the region. Finally, the broader implications of these works are explored, highlighting their potential to address global challenges such as energy accessibility, prosperity in conflict zones, and sharing these discoveries with the upcoming generations.</p>

A presente pesquisa teve por objetivo propor uma estrutura de modelagem matemática para a localização ótima de unidades de tratamento térmico de resíduos com recuperação energética. Para tal, o ferramental utilizado foi o método de programação inteira mista, sendo a modelagem desenvolvida aplicada para a Região Metropolitana da Baixada Santista e Litoral Norte. Foi considerada como premissa básica que o processo de incineração seria operado pelo poder público; todos os municípios geradores de Resíduos Sólidos Domiciliares foram considerados como potenciais localidades para a instalação da unidade de tratamento térmico de resíduos; todos os aterros sanitários que atendiam os Municípios estudados foram considerados para a recepção das escórias e cinzas provenientes do processo de incineração. Foram especificados quatro cenários para tal análise, que abordaram competitividade em relação ao uso de aterros sanitários e a presença de eficiência na coleta seletiva dos Municípios. Os resultados apontaram para que a unidade de tratamento térmico de resíduos se localize no entorno dos Municípios de Santos, Praia Grande e São Vicente. Mesmo com a opção do uso de aterros sanitários, a implantação da unidade de tratamento térmico de resíduos se apresentou como uma alternativa mais favorável, tendo sido levados em conta, na modelagem proposta, aspectos tanto ambientais como econômicos. / This study aimed to propose a mathematical modeling framework for optimal location of units of the thermal treatment of waste with energy recovery. To this end, the tool used was the method of mixed integer programming, and the developed modeling applied to the Santos Metropolitan Region and North Coast. It was considered as the basic premise that the incineration process would be operated by the Government; all municipalities solid waste generators were considered as potential locations for the installation of the unit thermal treatment of waste, all landfills that serve municipalities studied were considered for receipt of slag and ash from the incineration process. Four scenarios were specified for this analysis that addressed competitiveness in relation to the use of landfills and the presence of selective collection efficiency in the municipalities. Results showed that the unit of thermal treatment of waste should be located in the vicinity of the cities of Santos, São Vicente and Praia Grande. Even with the option of using landfill, the deployment of the unit of thermal treatment of waste is presented as an alternative more favorable, having been taken into account in the proposed model, both environmental and economic aspects.

Waste heat recovery is a multi-billion-dollar industry with a compound annual growth rate of 8.8% assessed between 2016 to 2024 and low-grade waste heat (< 230^oC ± 20^oC) makes up 66% of this ubiquitous resource. Thermoelectric generators are preferred for the recovery process because they are cheap and are well suited for this temperature range. They generate power by converting thermal potential to electric potential, known as the Seebeck effect. Since they have no moving parts, they are inherently immune to mechanical failure or an intermittent need for maintenance. However, the challenge has been to effectively harvest waste heat with these modules to generate power, using passive processes. This work is focused on designing a device for optimized harvesting of waste energy from the ambient with a custom, evaporatively-cooled heat sink. This heat sink is designed to passively handle the cooling of the other side of the thermoelectric module so as to enable the attainment of a minimum of 5V, which is the minimum voltage required to power small mobile devices. The heat sink model is similar to a loop heat pipe but engineered for compactness. To ensure this level of efficacy is attained, several studies are made to optimize the wick. Non-metal wicks were considered as they do not contribute to an increase in temperature of the compensation chamber in loop heat pipes. A non-metal wick integrated with nanoparticles is tested and results show a clear thermal management enhancement over similar but virgin non-metal wicks, at over 16%. The heat source section of the device is optimized for energy-harvesting in low grade temperature regimes by incorporating a near-black body coating on the metal heat source section. Experimental results show that both the heat source and sink sections were able to induce sufficient thermal potential for the thermoelectric modules to passively generate up to 5V using eight 40mm by 40mm Bismuth Telluride modules in 3.5 minutes. The prototype is relatively cheap, inherently reliable and presents the possibility of passively harvesting low-grade waste heat for later use, including powering small electronic devices.

A presente pesquisa teve por objetivo propor uma estrutura de modelagem matemática para a localização ótima de unidades de tratamento térmico de resíduos com recuperação energética. Para tal, o ferramental utilizado foi o método de programação inteira mista, sendo a modelagem desenvolvida aplicada para a Região Metropolitana da Baixada Santista e Litoral Norte. Foi considerada como premissa básica que o processo de incineração seria operado pelo poder público; todos os municípios geradores de Resíduos Sólidos Domiciliares foram considerados como potenciais localidades para a instalação da unidade de tratamento térmico de resíduos; todos os aterros sanitários que atendiam os Municípios estudados foram considerados para a recepção das escórias e cinzas provenientes do processo de incineração. Foram especificados quatro cenários para tal análise, que abordaram competitividade em relação ao uso de aterros sanitários e a presença de eficiência na coleta seletiva dos Municípios. Os resultados apontaram para que a unidade de tratamento térmico de resíduos se localize no entorno dos Municípios de Santos, Praia Grande e São Vicente. Mesmo com a opção do uso de aterros sanitários, a implantação da unidade de tratamento térmico de resíduos se apresentou como uma alternativa mais favorável, tendo sido levados em conta, na modelagem proposta, aspectos tanto ambientais como econômicos. / This study aimed to propose a mathematical modeling framework for optimal location of units of the thermal treatment of waste with energy recovery. To this end, the tool used was the method of mixed integer programming, and the developed modeling applied to the Santos Metropolitan Region and North Coast. It was considered as the basic premise that the incineration process would be operated by the Government; all municipalities solid waste generators were considered as potential locations for the installation of the unit thermal treatment of waste, all landfills that serve municipalities studied were considered for receipt of slag and ash from the incineration process. Four scenarios were specified for this analysis that addressed competitiveness in relation to the use of landfills and the presence of selective collection efficiency in the municipalities. Results showed that the unit of thermal treatment of waste should be located in the vicinity of the cities of Santos, São Vicente and Praia Grande. Even with the option of using landfill, the deployment of the unit of thermal treatment of waste is presented as an alternative more favorable, having been taken into account in the proposed model, both environmental and economic aspects.