Made available in DSpace on 2014-12-17T14:56:16Z (GMT). No. of bitstreams: 1 AugustoCFW_DISSERT.pdf: 4069800 bytes, checksum: c488b0f09f064b7a5254eca8a4fff499 (MD5) Previous issue date: 2013-08-30 / The generation of electricity in Brazil is predominantly renewable, with internal hydraulic generation being more than 70% of its energy matrix. The electricity rationing occurred in 2001 due to lack of rain, led the country to increase the participation of alternative energy sources. This need for new sources of energy makes the regional potential to be exploited, which configures the change of generation model from centralized generation to distributed generation. Among the alternative sources of energy, the solar energy is presented as very promising for Brazil, given that most of its territory is located near to the equator line, which implies days with greater number of hours of solar radiation. The state of Rio Grande do Norte (RN) has one of the highest levels of solar irradiation of the Brazilian territory, making it eligible to receive investments for the installation of photovoltaic solar plants. This thesis will present the state-of-the-art in solar photovoltaic power generation and will examine the potential for generation of solar photovoltaic power in Brazil and RN, based on solarimetrics measurements conducted by various institutions and also measurements performed in Natal, the state capital / A gera??o de energia el?trica no Brasil ? predominantemente renov?vel, com a gera??o interna hidr?ulica sendo superior a 70% do total de sua matriz energ?tica. O racionamento de energia el?trica ocorrido em 2001, devido ? falta de chuvas, levou o pa?s a incrementar a participa??o de fontes alternativas de energia. Esta necessidade por novas fontes de energia faz com que as potencialidades regionais sejam aproveitadas, o que configura a mudan?a do modelo de gera??o, passando de gera??o centralizada para gera??o distribu?da. Dentre as fontes alternativas de energia, a solar apresenta-se como uma fonte bastante promissora para o Brasil, tendo em vista que a maior parte do seu territ?rio est? localizada pr?ximo ? linha do equador, o que implica em dias com maior quantidade de horas de radia??o solar. O Estado do Rio Grande do Norte (RN) tem um dos maiores ?ndices de incid?ncia solar do territ?rio brasileiro, o que o torna apto a receber investimentos para a instala??o de usinas solares fotovoltaicas. Esta disserta??o apresentar? o estado da arte em gera??o de energia solar fotovoltaica e analisar? o potencial de gera??o da energia solar fotovoltaica no Brasil e no RN, baseando-se em medi??es solarim?tricas realizadas por diversas institui??es e tamb?m em medi??es realizadas em Natal

Made available in DSpace on 2014-07-29T12:05:39Z (GMT). No. of bitstreams: 1 tese ana.pdf: 3317264 bytes, checksum: 1b832f28771563b1839c5af29d886623 (MD5) Previous issue date: 2008-09-11 / Este trabalho apresenta o desenvolvimento de uma modelagem para inserção de restrição de qualidade de água ao planejamento da operação de sistemas hidrotérmicos de longo prazo. Considerar a qualidade da água no planejamento garante, o enfoque do uso múltiplo da água. O objetivo deste é explorar a sensibilidade do planejamento de sistemas hidrotérmicos à inserção de uma variável ambiental, focando a qualidade da água. Dentre os indicadores de qualidade da água, a escolha foi pela clorofila-a e aporte de fósforo estabelecendo uma relação com o volume do reservatório. / Este trabalho apresenta o desenvolvimento de uma modelagem para inserção de restrição de qualidade de água ao planejamento da operação de sistemas hidrotérmicos de longo prazo. Considerar a qualidade da água no planejamento garante, o enfoque do uso múltiplo da água. O objetivo deste é explorar a sensibilidade do planejamento de sistemas hidrotérmicos à inserção de uma variável ambiental, focando a qualidade da água. Dentre os indicadores de qualidade da água, a escolha foi pela clorofila-a e aporte de fósforo estabelecendo uma relação com o volume do reservatório.

Encontrar soluções para a problemática dos resíduos e, em virtude da crescente demanda por energia, diminuir a dependência dos combustíveis fósseis têm constituído grandes desafios para os pesquisadores. O setor hospitalar é um potencial gerador dos chamados Resíduos de Serviços de Saúde (RSS) que também apresenta um alto consumo de energia em decorrência do seu período de funcionamento e de equipamentos que necessitam de infraestrutura adequada. Apesar de representarem uma pequena parcela perante o montante dos Resíduos Sólidos Urbanos (RSU), no Brasil, nem todos os geradores se preocupam com seu tratamento e destinação final. O emprego de tecnologias desenvolvidas para o tratamento desses resíduos com a possibilidade de recuperação energética deve ser avaliado. O Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto (HC-FMRP-USP) gera cerca de 1,9 ton/dia de RSS. Nesse contexto, o objetivo geral desta pesquisa foi avaliar a viabilidade legal, ambiental e econômico-financeira da implantação de um sistema próprio de tratamento de RSS no HCFMRP- USP para geração de energia. A metodologia foi estruturada em pesquisa exploratória, coleta de dados por meio de entrevistas semi-estruturadas com responsáveis pelo setor dos RSS no hospital, com pesquisadores da área da saúde, de escolas de engenharia, órgãos técnicos e indústrias fabricantes dos equipamentos; levantamento bibliográfico e análise de conteúdo. Para a avaliação econômico-financeira, foi empregada a avaliação custoefetividade. Estudos comparativos sobre os tipos de tratamento disponíveis e utilizados nacionalmente foram considerados. Assim, o processo que melhor se adequou ao sistema proposto foi o da incineração com tecnologia de gaseificação e combustão combinadas (GCC). Os resultados demonstraram que o sistema proposto está sob a égide da lei contemplando, inclusive, a Política Nacional de Resíduos Sólidos (PNRS), desde que mediante anuência do Conselho Gestor do campus da USP e de sua Comissão de Meio Ambiente, além do devido processo de licenciamento ambiental junto à CETESB e pré-análise dos RSS. Contudo, sob o aspecto ambiental há questões públicas e políticas sobre a aceitação de sua implantação no complexo hospitalar. Embora haja o emprego de avançada tecnologia, o equipamento avaliado necessita de instalação, manutenção e monitoramento adequados por profissionais capacitados para operá-los, a fim de se evitar possíveis danos às pessoas e ao meio-ambiente, para isso, os envolvidos devem agir com responsabilidade. Por fim, sob o aspecto econômico-financeiro houve um empate técnico entre os custos do tratamento realizado atualmente e os da proposta do investimento. Assim, esse último aspecto avaliado incidiu sobre o benefício implícito da decisão de se implantar ou não o processo. Portanto, considera-se a viabilidade da implantação de um sistema próprio para tratamento de RSS no HCFMRP-USP para geração de energia sob os três aspectos: legal, ambiental e econômicofinanceiro. / Finding solutions to the waste problem and reducing dependence on fossil fuels due to the growing demand for energy have become big challenges for researchers to deal with. Hospitals are large producers of Medical waste (MW) and also big energy consumers due to their long running hours and the running of equipment that demands adequate infrastructure. Despite accounting for a small share of all the Municipal Solid Waste (MSW) not all producers, in Brazil, are concerned about waste treatment and its final destination. The use of technologies developed with the aim of treating such waste in order to generate energy has to be assessed. The Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto (HCFMRP-USP) generates around 1.9 tons of waste per day. In this context, the general aim of this research program was to assess the legal, environmental and economic-financial feasibility of the implementation of a private system of biomedical waste treatment at HCFMRP-USP in order to generate energy. The method was structured in exploratory research, data gathering by means of semi-structured interviews with MW department staff at the hospital, with Health researchers, with Engineering College researchers, technical organizations and equipment manufacturers, besides bibliographic referencing and content analysis. Cost-effectiveness analysis was used for the economic-financial analysis. Comparative studies of the types of treatment available and used nationwide were taken into consideration. Thus, the process which best suited the proposed system was that of incineration by means of Gasification Combined Cycle (GCC). Results showed that the proposed system is under the support of Law and it also takes into consideration the National Policy for Solid Waste (NPSW), provided that it has the approval of the Director Council of the Administration of the campus of USP and of its Environment Committee as well as appropriate environmental licenses granted by CETESB and pre-analysis of MW. However, under the environmental aspect, there are public and political issues regarding the acceptance of this implementation in the hospital premises. Although there is the use of advanced technology, the equipment which was assessed needs to be installed, maintained and monitored adequately by professionals trained to operate it so as to avoid possible damage to humans and the environment. Staff involved must be responsible. Finally, under the economic-financial aspect there was a draw between the costs of the treatment conducted at present and those of the proposed investment. Therefore, this last aspect assessed prevailed over the implicit benefit of the decision on whether to implement the process or not. However, the feasibility of the implementation of a private MW treatment system at HC-FMRP-USP in order to generate energy is to be considered under the legal, environmental and economicfinancial aspects.

The awareness of the human responsibility in global warming has led to various private and public initiatives to reduce the emission of greenhouse gases, up to international level. In this context the development of renewable technologies in two sectors having an important ecological footprint, i.e. production of electricity and transportation, is targeted.In the firstly mentioned sector, the progression of wind energy is at present the most rapid among all renewable energies. But wind turbines still suffer from a global lack of reliability and accessibility compared to classical power plants, leading to potentially important production losses and repair costs. The first part of the present work focuses on the improvement of the electrical chain reliability by the combination of an estimator and a fault-detection algorithm to achieve sensor-fault tolerance, taking benefit from the already available measurement redundancies on doubly-fed-induction-machine (DFIG) drives.Estimators and sensor-fault detection and isolation (FDI) in DFIGs have been the object of many research papers. However, most of them only consider one unique type of measurement and only a few works consider magnetic saturation. A new combination of a closed-loop observer with a cumulative-sum-based FDI technique, considering magnetic saturation and using limited computational resources is proposed here to estimate electromagnetic torque, rotor currents and position for sensor-fault detection and tolerance. This algorithm is then validated in steady state and in case of moderate transients, unbalanced conditions and misestimation of DFIG parameters. The estimator can also start on the fly during the start-up process of the generator.In the transportation sector, new hybrid and full-electric vehicles start to be visible on the roads, but still need important technological improvements in terms of autonomy, performances, but also produced noise and vibrations. The objectives of the second part of this doctoral thesis are related to this last challenge and consist of the experimental investigation of noise, vibration and harshness (NVH) aspects of an 8/6 switched-reluctance machine (SRM) designed for an electrical vehicle (EV).The NVH issues of SRMs, limiting their usage in automotive and other domains, have been the subject of various papers. However, most of them focus on modal analysis or detailed phenomena, while a global evaluation of NVH aspects of SRMs in normal working conditions is rarely made, as well as the use of reproducible sound metrics. A global and relatively fast experimental method to assess the evolution of noise and vibration is proposed. Tests are performed in transient regime, using continuously varying working conditions when possible, for the excitation of a large band of frequencies. The resulting current, radial vibration and acoustic noise are presented as spectrograms for an easy distinction of affected and unaffected frequencies and compared with the associated loudness and sharpness.Furthermore, the implementation of a new faster-sampled current-hysteresis controller has allowed to improve the quality of the control and of the acoustic noise by reducing the current-ripple amplitude and the excitation of resonances. The various tests show that the switching frequency has to be high enough to avoid exciting the ovalization mode of the SRM, but not too high to avoid producing a too sharp noise. The ripple amplitude also has to be considered to limit the loudness. Therefore, soft chopping, or a reduced DC-bus voltage at low speeds, has to be preferred with a relative small hysteresis bandwidth. Finally, the case of an open-phase fault has been investigated showing amplified even current orders in the vibration and acoustic-noise plots. / La prise de conscience de la responsabilité humaine dans le réchauffement climatique est à la source de nombreuses initiatives publiques et privées parfois internationales pour réduire les émissions de gaz à effet de serre. Dans ce contexte, le développement de technologies durables dans deux secteurs à forte empreinte écologique est visé: la production d'énergie électrique et les transports. Dans le premier secteur, la progression de l'éolien est à présent la plus rapide parmi toutes les énergies renouvelables. Cependant, les éoliennes souffrent d'un manque global de fiabilité et d'accessibilité par rapport aux centrales électriques classiques, ce qui conduit potentiellement à des pertes de production et des coûts de réparation importants. La première partie de ce travail se focalise sur l'amélioration de la chaîne électrique en la rendant tolérante aux défauts de capteurs au moyen de la combinaison d'un estimateur et d'un algorithme de détection de défauts, tirant avantage de la redondance de mesures déjà présente sur les entraînements à machines asynchrones à double alimentation (MADA). Les estimateurs et la détection et l'isolation de défauts de capteurs sur les MADA a fait l'objet de nombreuses publications scientifiques. Cependant, la plupart d'entre elles considèrent un seul type de mesure et peu de travaux prennent en compte la saturation magnétique. Une nouvelle combinaison d'un observateur et d'un algorithme de détection de défauts de type ‘CUSUM', considérant la saturation magnétique et nécessitant une puissance de calcul limitée, est proposée dans cette thèse pour l'estimation du couple électromagnétique, des courants et de la position rotoriques en vue d'obtenir la tolérance aux défauts de capteurs. Cet algorithme est validé en régime permanent et cas de transitoires modérés, de tensions du réseau déséquilibrées et d'erreurs d'estimation des paramètres de laMADA. L'estimateur est aussi capable de démarrer seul lors du démarrage de la génératrice. Dans le secteur des transports, des véhicules hybrides et électriques commencent à être visibles sur les routes, malgré que des progrès technologiques importants en termes d'autonomie, de performances, mais aussi de bruits et vibrations soient encore nécessaires pour une utilisation plus intensive. L'objectif de la deuxième partie de cette thèse se rapporte à ce dernier défi et consiste à analyser les aspects acoustiques et vibratoires d'une machine à réluctance variable 8/6 conçue pour propulser un véhicule électrique. Ces problèmes acoustiques et vibratoires, qui limitent notamment l'usage de telles machines dans des applications de propulsion, ont été l'objet de divers articles scientifiques. Cependant, la plupart d'entre eux sont focalisés sur des analyses modales ou de phénomènes particuliers, alors qu'une évaluation globale des problèmes de bruit et de vibration des machines à réluctance variable en conditions normales de fonctionnement est rarement proposée, de même que l'utilisation de critères de qualité sonore. Une méthode expérimentale globale et relativement rapide pour évaluer l'évolution du bruit et des vibrations est proposée dans ce travail. Les essais sont réalisés en régime transitoire pour exciter une large bande de fréquences et en faisant varier continuellement, quand cela est possible, les conditions de fonctionnement. Les courants, vibrations radiales et bruits acoustiques résultants sont présentés sous formes de cartographies couleur pour une distinction aisée des fréquences affectées et non-affectées et comparés aux niveaux calculés de bruyance et d'acuité correspondants. Par ailleurs, la mise en place d'un nouveau régulateur à hystérèse en courant à plus grande fréquence d'échantillonnage a permis d'améliorer la qualité de la commande et du bruit acoustique associé en réduisant l'amplitude des oscillations de courant et l'excitation des fréquences de résonance. Les essais montrent que la fréquence de commutation doit être suffisamment élevée pour éviter l'excitation du mode d'ovalisation de la machine, mais pas trop pour éviter une trop grande acuité du son produit. L'amplitude des oscillations doit aussi être considérée pour limiter la bruyance. En conséquence, une commande en ‘soft chopping', ou une tension réduite du bus continu à basse vitesse, doit être combinée à une bande d'hystérèse relativement faible. Enfin, le cas d'un défaut de phase ouverte a été étudié et a montré une amplification des ordres pairs du courant dans les spectres vibratoires et acoustiques. / De bewustwording van de menselijke verantwoordelijkheid in de opwarming van de aarde heeft tot verschillende private en publieke initiatieven geleid om de uitstoot van broeikasgassen te verminderen. In deze context is de ontwikkeling van hernieuwbare technologieën hoofdzakelijk gericht op twee sectoren met een belangrijke ecologische impact: elektriciteitsproductie en transport.In de eerste sector ontwikkelt windenergie zich op dit moment sneller dan alle andere hernieuwbare energieën. Maar windturbines lijden nog steeds aan een gebrek aan betrouwbaarheid en toegankelijkheid, en dus aan potentieel hogere productieverliezen en herstelkosten, als ze met klassieke krachtcentrales worden vergeleken. In het eerste deel van deze doctoraatsthesis wordt op de verbetering van de elektrische keten geconcentreerd door de combinatie van een schatter en een foutdetectie- en -isolatiealgoritme (FDI-algoritme) om sensorfouttolerantie te verkrijgen dankzij de reeds aanwezige meetovertolligheid op dubbelgevoede inductiemachine (DFIG) aandrijvingen.Schatters en sensor-FDI-algoritmen zijn het onderwerp van vele wetenschappelijke artikelen geweest. Meestal wordt maar één sensortype beschouwd en met de magnetische verzadiging wordt niet vaak rekening gehouden. Een nieuwe combinatie van een schatter met gesloten terugkoppeling en een FDI-techniek gebaseerd op het ‘cumulative-sum' principe is voorgesteld. Zo kan het elektromagnetische koppel, de rotorstromen en positie worden geschat voor sensor FDI en fouttolerantie met beperkte rekenkosten en zonder de magnetische verzadering te verwaarlozen. Het algoritme wordt in stabiele toestand gevalideerd, maar ook in het geval van gematigde transiënte situaties, onevenwichtige netwerkomstandigheden en een verkeerde schatting van DFIG parameters. Het kan ook vanzelf starten tijdens de startprocedure van de generator.In de vervoersector beginnen hybride en elektrische voertuigen op de wegen te rijden. Maar vooreen intensiever gebruik van zo'n wagens zijn er nog technologische verbeteringen nodig met betrekking tot autonomie, prestaties en ook geluid en trillingen (NVH). Het tweede deel van de thesis betreft die laatste uitdaging en bestaat uit het experimentele onderzoek van geluid en trillingen op een 8/6 variabelereluctantiemachine (SRM) ontwikkeld voor elektrische voertuigen.De NVH-problemen van SRM's beperken hun gebruik in automobiele en andere toepassingen enonderzoek wordt erover voortgezet. Vele wetenschappelijke artikelen focussen toch op modale analyse of gedetailleerde fenomenen terwijl een globale evaluatie van NVH aspecten in SRM's in gewone operatiecondities nauwelijks wordt gemaakt. Hetzelfde geldt voor het gebruik van reproduceerbare geluidsmetrieken. Een globale en vrij vlugge experimentele methode is hier voorgesteld om het NVH gedrag te schatten. Testen worden in transiënte situaties uitgevoerd om een brede frequentieband te exciteren, indien mogelijk met voortdurend variërende condities. De gemeten fasestroom, trilling en geluid worden als kleurmappen geplot om het verschil tussen beïnvloede en niet geaffecteerde frequenties te vergemakkelijken en met de berekende akoestische luidheid en scherpte vergeleken.Bovendien heeft de implementatie van een sneller bemonsterd stroomhysteresisregelaar geleid tot een verbetering van de regulatie- en akoestische kwaliteit door de amplitude van de stroomrimpeling en de excitatie van resonantiefrequenties te verminderen. De testresultaten tonen dat de schakelfrequentie voldoende hoog moet zijn om de excitatie van de ovale vervormingsmode te vermijden, maar niet te hoog om de scherpte van het geluid te beperken. De amplitude van de rimpel beïnvloedt ook de luidheid en daarvoor moet in aanmerking worden genomen. Bijgevolg zou ‘soft chopping'mode, of een lagere spanning op de DC-bus bij lage toerentallen, met een relatief klein hysteresisband beter worden gebruikt. Uiteindelijk wordt het geval van een openfasefout bestudeerd en onthult versterkte gelijke frequentievolgorden in de trilling- en geluidplots. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

<p>The purpose of this study is to develop a flexible computer tool to predict the power produced by a photovoltaic (PV) panel. The performance of the PV panel is dependent on the incident solar radiation and the cell temperature. The computer tool predicts voltage-current curves, power-voltage curves, and maximum power point values. Five different models are implemented to predict the temperature of the panel, and comparison between the different thermal models is good. A thermal capacitance approach that uses a simple relationship for the forced convection heat transfer coefficient is used to predict the cell temperature. Both the electrical and temperature models are verified through comparisons using PVWatts and validated by comparisons to measured values. The model is flexible in the sense that it can be applied to PV arrays of any size, at any location, and of different cell types. After being verified and validated, the model is used to investigate the effects of cooling on the photovoltaic panel to improve the panel efficiency and increase its power output. Typical results show that for every degree Celsius rise in temperature, the efficiency of the solar panel is reduced by 0.5%. The effect of cooling and the resulting increase in energy production in two different climatic zones are studied and discussed. </p>

The pandemic scenario caused by COVID-19 is an event with no precedent. Therefore, it<br>is a phenomenon that can be studied to observe how electricity loads have changed during the stayat-home order weeks. The data collection process was done through online surveys and using<br>publicly available data. This study is focusing on analyzing household energy units such as<br>appliances, HVAC, lighting systems. However, collecting this data is expensive and timeconsuming since dwellings would have to be studied individually. As a solution, previous studies<br>have shown success in characterizing residential electricity using surveys with stochastic models.<br>This characterized electricity consumption data allows the researchers to generate a predictive<br>model, make a regression and understand the data. In that way, the data collection process will not<br>be as costly as installing measuring instruments or smart meters. The input data will be the<br>behavioral characteristics of each participant; meanwhile, the output of the analysis will be the<br>estimated electricity consumption "kWh." After generating the "kWh" target, a sensitivity analysis<br>will be done to observe the electricity consumption through time and examine how people evolved<br>their load during and after the stay-at-home order.<br>This research can help understand the change in electricity consumption of people who<br>worked at home during the pandemic and generate energy indicators and costs such as home office<br>electricity cost kWh/year. In addition to utilities and energy, managers can benefit from having a<br>clear understanding of domestic consumers during emergency scenarios as pandemics. <br>

This master´s thesis deals with possibilities of accumulation electric energy with the electric vehicles and their use for electric grid regulation services. In the introduction of this thesis is characterized the current world-wide state of electromobility, including the Czech Republic. Furthermore are summarized main advantages and disadvantages of the expanded involvement of the electric vehicles in the traffic. In the second part if this Master´s thesis the vehicles are divided into three main groups. The third part of the thesis describes the energy storage and generation units used in vehicles. In this part of the script are each of the energy storage parameters compared. The other chapter includes the list of current battery electric vehicles with all their important technical parameters. The fifth chapter summarizes the possibilities of the use of electric vehicles in the Vehicle-to-grid system. This chapter also discusses in detail the ancillary services of the electric grid in the Czech Republic. In the last part of this Master´s thesis there is calculated an economical potential of electric vehicles providing the primary and secondary regulation.

<div>In this paper various applications of axial tensile load, bending load, and rolling loading has been applied to a Copper Indium Gallium Diselenide (CIGS) Solar Cell to lean how it would affect the solar cell parameters of: Open circuit voltage (Voc), Short circuit current, (Isc), Maximum power (Pmax), and Efficiency (EFF), and Fill Factor (FF). These Relationships were found for with three different experiments. The first experiment the applies axial tensile stress is to a CIGS solar cell ranging from 0 to 200 psi with various strain rates: 0.0001, 0.001, 0.01, and 0.1 in/sec as well as various relaxation time: 1min, 5min, and 10 min while the performance of solar cell is measured. The results of this gave several trends couple pertaining the Voc . The first is that open circuit voltage increases slightly with increasing stress. The second is the rate of increase (the slope) increases with longer relaxation times. The second set of trend pertains to the Isc. The first is that short circuit current generally is larger with larger stress. The second is there seems to be a general increase in the Isc up to a given threshold of stress. After that threshold the Isc seems to decrease. The threshold stress varies depending on strain rate and relaxation time. The second set of experiments consisted of holding a CIGS solar cell in a fixed curved position while it was in operational use. The radii of the curved cells were: 0.41, 0.20, 0.16, 0.13, 0.11, 0.094, and 0.082 m. The radii were performed for both concave and convex cell curvature. The trends for this show a slight decrease in all cell parameters with decreasing radii, the exception being Voc which is not effecting, the convex curvature causing a slightly faster decrease than the concave. This set of experiments were also processed to find the trends of the single diode model parameters of series resistance (Rs), shunt resistance (Rsh), dark current (I0), and saturation current (IL), which agreed with the experimental results. The second experiment consisted of rolling a CIGS solar cell in tensile (cells towards dowel.) and compression (cells away from dowel) around a dowel to create internal damage. The diameter of the dowels decreased. The dowel diameters were: 2. 1.75, 1.25, 1, 0.75, 0.5, and 0.25 inches. This experiment showed similar trends as the bending one but also had a critical diameter of 1.75 in where beyond that damage much greater. Finally a parametric study was done in COMSOL Multiphysics® to examine how changes in the CIGS material properties of electron mobility (EM), electron life time, (EL), hole mobility 15 (HM), and Hole life time (HL) effect the cell parameters. The trends are of an exponential manner that converges to a given value as the material properties increase. When EL, EM, HL are very small, on the order of 10-4 times smaller than their accepted values, a transient like responses occurs.<br></div>

This research focuses on developing strategies for the optimal control of large-scale Combined Cooling, Heating and Power (CCHP) systems to meet electricity, heating, and cooling demands, and evaluating the cost savings potential associated with it. Optimal control of CCHP systems involves the determination of the mode of operation and set points to satisfy the specific energy requirements for each time period. It is very complex to effectively design optimal control strategies because of the stochastic behavior of energy loads and fuel prices, varying component designs and operational limitations, startup and shutdown events and many more. Also, for large-scale systems, the problem involves a large number of decision variables, both discrete and continuous, and numerous constraints along with the nonlinear performance characteristic curves of equipment. In general, the CCHP energy dispatch problem is intrinsically difficult to solve because of the non-convex, non-differentiable, multimodal and discontinuous nature of the optimization problem along with strong coupling to multiple energy components. <div><br></div><div>This work presents a solution methodology for optimizing the operation of a campus CCHP system using a detailed network energy flow model solved by a hybrid approach combining mixed-integer linear programming (MILP) and nonlinear programming (NLP) optimization techniques. In the first step, MILP optimization is applied to a plant model that includes linear models for all components and a penalty for turning on or off the boilers and steam chillers. The MILP step determines which components need to be turned on and their respective load needed to meet the campus energy demand for the chosen time period (short, medium or long term) with one-hour resolution. Based on the solution from MILP solver as a starting point, the NLP optimization determines the actual hourly state of operation of selected components based on their nonlinear performance characteristics. The optimal energy dispatch algorithm provides operational signals associated with resource allocation ensuring that the systems meet campus electricity, heating, and cooling demands. The chief benefits of this formulation are its ability to determine the optimal mix of equipment with on/off capabilities and penalties for startup and shutdown, consideration of cost from all auxiliary equipment and its applicability to large-scale energy systems with multiple heating, cooling and power generation units resulting in improved performance. </div><div><br></div><div>The case-study considered in this research work is the Wade Power Plant and the Northwest Chiller Plant (NWCP) located at the main campus of Purdue University in West Lafayette, Indiana, USA. The electricity, steam, and chilled water are produced through a CCHP system to meet the campus electricity, heating and cooling demands. The hybrid approach is validated with the plant measurements and then used with the assumption of perfect load forecasts to evaluate the economic benefits of optimal control subjected to different operational conditions and fuel prices. Example cost optimizations were performed for a 24-hour period with known cooling, heating, and electricity demand of Purdue’s main campus, and based on actual real-time prices (RTP) for purchasing electricity from utility. Three optimization cases were considered for analysis: MILP [no on/off switch penalty (SP)]; MILP [including on/off switch penalty (SP)] and NLP optimization. Around 3.5% cost savings is achievable with both MILP optimization cases while almost 10.7% cost savings is achieved using the hybrid MILP-NLP approach compared to the current plant operation. For the selected components from MILP optimization, NLP balances the equipment performance to operate at the state point where its efficiency is maximum while still meeting the demand. Using this hybrid approach, a high-quality global solution is determined when the linear model is feasible while still taking into account the nonlinear nature of the problem. </div><div><br></div><div>Simulations were extended for different seasons to examine the sensitivity of the optimization results to differences in electric, heating and cooling demand. All the optimization results suggest there are opportunities for potential cost savings across all seasons compared to the current operation of the power plant. For a large CCHP plant, this could mean significant savings for a year. The impact of choosing different time range is studied for MILP optimization because any changes in MILP outputs impact the solutions of NLP optimization. Sensitivity analysis of the optimized results to the cost of purchased electricity and natural gas were performed to illustrate the operational switch between steam and electric driven components, generation and purchasing of electricity, and usage of coal and natural gas boilers that occurs for optimal operation. Finally, a modular, generalizable, easy-to-configure optimization framework for the cost-optimal control of large-scale combined cooling, heating and power systems is developed and evaluated.</div>

Due to an intensified climate change discourse, renewable energy technologies find higher attention within the energy system and increasingly compete with traditional energy conversion systems. Electricity is progressively being generated through renewable electricity generation technologies (REGT) which harness naturally existing energy fluxes (wind, tide, heat, sun) and convert it to electricity. High investments are currently being made into well-developed REGT using explored energy sources such as wind, hydro or solar. In order to increase cost- and energy efficiency of REGTs, university research projects are developing new REGTs that harvest underexplored energy sources such as the marine energy source. These capital-intensive marine energy research projects are entering the market through university spin-off firms but are often confronted with funding gaps, for the current or future operations. Capital rich investors could provide these funds but are often investing in well explored energy sources rather than into underexplored but more cost- and energy-efficient energy sources. Utilizing a qualitative, grounded theory-influenced approach and combining empirical material of semi-structured interviews, data from a participant observation of an innovation system workshop attendance and data from continuous meetings with an academic REGT spin-off from Uppsala University, this study investigates 1) the drivers and barriers within the funding ecosystem for academic REGT spin-offs in Sweden, 2) the limited access of high capital to underexplored energy sources on the specific case of the marine energy source and 3) a potential common ground for investors with high capital and academic REGT spin-offs in order to allow an accelerated diffusion of the marine energy source. The results indicate that the physical properties of the underexplored marine source should not be accounted for as driver but rather as the foundation of an academic REGT spin-off. This frame allows to bridge practitioners of both the investment field and the academic field of REGT spin-offs through the degree of utilization. An inversion of relations, where not only entrepreneurs increasingly link their field of study to economy and business, but also investors adapt cross-disciplinary knowledge towards academia and natural sciences via the degree of utilization, could be beneficial for an accelerated diffusion of academic REGTs. Bridging practitioners of both fields through the degree of utilization and other means might together with a full commercial application and proof of marine REGTs reduce the funding gap of academic spin-offs in the marine sector and allow access to investors with high capital.