04 Fakultät Energie-, Verfahrens- und Biotechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/5
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Item Open Access Wege zur Ermittlung von Energieeffizienzpotenzialen von Informations- und Kommunikationstechnologien(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2020) Miller, Michael; Hufendiek, Kai (Prof. Dr.-Ing.)Item Open Access Global potentials and costs of synfuels via Fischer-Tropsch process(2023) Buchenberg, Patrick; Addanki, Thushara; Franzmann, David; Winkler, Christoph; Lippkau, Felix; Hamacher, Thomas; Kuhn, Philipp; Heinrichs, Heidi; Blesl, MarkusThis paper presents the potentials and costs of synthetic fuels (synfuels) produced by renewable energy via PEM water electrolysis and the subsequent Fischer-Tropsch process for the years 2020, 2030, 2040, and 2050 in selected countries across the globe. The renewable energy potential was determined by the open-source tool pyGRETA and includes photovoltaic, onshore wind, and biomass. Carbon dioxide is obtained from biomass and the atmosphere by direct air capture. The potentials and costs were determined by aggregating minimal cost energy systems for each location on a state level. Each linear energy system was modelled and optimised by the optimisation framework urbs. The analysis focused on decentralised and off-grid synthetic fuels’ production. The transportation costs were roughly estimated based on the distance to the nearest maritime port for export. The distribution infrastructure was not considered since the already-existing infrastructure for fossil fuels can be easily adopted. The results showed that large amounts of synthetic fuels are available for EUR 110/MWh (USD 203/bbl) mainly in Africa, Central and South America, as well as Australia for 2050. This corresponds to a cost reduction of more than half compared to EUR 250/MWh (USD 461/bbl) in 2020. The synfuels’ potentials follow the photovoltaic potentials because of the corresponding low levelised cost of electricity. Batteries are in particular used for photovoltaic-dominant locations, and transportation costs are low compared to production costs.Item Open Access Findings from measurements of the electric power demand of air compressors(2021) Hummel, Ulf; Radgen, Peter; Ülker, Sercan; Schelle, RalphThe compressed air electric ratio (CAER) describes the ratio of the real electric power demand to the nominal mechanical power of an air compressor. The CAER is an important indicator as the electric power demand of air compressors varies throughout its operation dependent on compressor technology, pressure ratio, and free air delivery. The nameplate power of the compressor drive motor is not sufficient for evaluating the electric power demand; therefore, the CAER plays an important role in assessing the electric operating power demand. In this paper, results from measurements of fixed speed and variable speed (VFD) compressors are presented with the analysis of key influencing factors of the CAER. The data show that the pressure ratio of operating pressure to the maximum design outlet pressure has the largest impact on the CAER. For VFD compressors, the CAER is represented as a linear function dependent on the respective load. Fixed and variable speed compressors’ CAERs are always dependent on the load condition. In idle condition, the CAER was measured to be 0.2. In full load condition with a pressure ratio of 0.6, the CAER averages at a value of 0.87, meaning a 90 kW compressor at 0.6 pressure ratio draws 78.3 kW electric power.Item Open Access Multi-criteria comparison of energy and environmental assessment approaches for the example of cooling towers(2022) Wenzel, Paula M.; Radgen, PeterCooling towers remove economically or technically unusable heat using considerable amounts of electricity and, in many cases, water. Several approaches, which vary in methodology, scope, and level of detail, are used for environmental evaluations of these cooling systems. Although the chosen approach has a significant impact on decisions made at the plant level, no methodology has yet been standardized for selecting the approach that best serves the objectives of the evaluation. Thus, this paper provides comparison criteria for the systematic selection of suitable evaluation methods for cooling towers and classifies how the methods score in this respect. These criteria, such as ‘life cycle thinking’, ‘inventoried physical quantities’, ‘temporal resolution’, ‘formalization’, and ‘data availability’, are grouped by overall evaluation objectives such as ‘thoroughness’, ‘scientific soundness’, and ‘usability’. Subsequently, these criteria were used to compare material flow analysis, energy analysis, environmental network analysis, life cycle inventory, life cycle assessment, environmental footprint methods, emergy analysis, exergy analysis, and the physical optimum method. In conclusion, material flow analysis is best suited for the analysis of cooling towers when impact assessment is not required; otherwise, life cycle assessment meets most of the defined criteria. Moreover, only exergy-based methods allow for the inclusion of volatile ambient conditions.Item Open Access Effiziente und konsistente Strukturen - Rahmenbedingungen für die Nutzung von Wärmeenergie in Privathaushalten(2010) Koch, Andreas (Hrsg.); Jenssen, Till (Hrsg.)Der vorliegende Bericht fasst die Arbeiten zur Strukturanalyse des vom Bundesministerium für Bildung und Forschung (BMBF) im Rahmen der Sozialökologischen Forschung (SÖF) geförderten Projektes „Energie nachhaltig konsumieren – nachhaltige Energie konsumieren: Wärmeenergie im Spannungsfeld von sozialen Bestimmungsfaktoren, ökonomischen Bedingungen und ökologischem Bewusstsein“ zusammen. Im Fokus dieses Projektes steht die Akteursebene mit der Erforschung der Hemmnisse und Anreize für nachhaltiges Konsumverhalten im Bereich der Wärmeenergie. Hierzu werden die auf der Mikroebene angesiedelten individuellen Wahrnehmungen, der Wissensstand sowie die Entscheidungs- und Handlungsstrategien von Akteuren in Bezug auf den Wärmekonsum analysiert. Individuelles Konsumverhalten im Wärmeenergiebereich ist sowohl von strukturellen Rahmenbedingungen, wie Siedlungs- und Gebäudestrukturen, rechtlichen Rahmenbedingungen, Förderinstrumenten und technologischen Systemen geprägt, als auch durch ein breit gestreutes Akteursgeflecht, wie z.B. Architekt/innen, Wohnungsbaugesellschaften, Handwerker/innen oder Wärmetechnologieanbieter im Umfeld der Konsument/innen beeinflusst. Dieses Struktur- und Akteursumfeld der Konsument/innen wurde daher im Vorfeld der eigentlichen Konsumentenanalyse systematisch im Hinblick auf Chancen und Hemmnisse für einen nachhaltigen Wärmeenergiekonsum analysiert und bewertet. Der vorliegende Bericht konzentriert sich darauf, das Strukturgeflecht, in welchem sich der/die Konsument/in bewegt, umfassend zu beschreiben, strukturelle Hemmnisse für nachhaltigen Wärmekonsum zu identifizieren und Ansätze auf der Strukturebene aufzuzeigen, die als Chancen für nachhaltiges Wärmekonsumverhalten zu interpretieren sind. Als strukturelle Rahmenbedingungen des Wärmekonsums werden im Projekt Gebäude- und Siedlungsstrukturen, Versorgungstechnologien sowie rechtliche und förderpolitische Instrumente erörtert. Diese Faktoren geben den Handlungsrahmen vor (bzw. beeinflussen diesen), innerhalb dem sich Konsument/innen nachhaltig verhalten können.Item Open Access A model-based framework for the assessment of energy-efficiency and CO2-mitigation measures in multi-cylinder paper drying(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2022) Godin, Hélène; Radgen, Peter (Prof. Dr.-Ing.)Thesis on the effect of energy-efficiency and CO2-mitigation measures in multi-cylinder paper drying.Item Open Access Operational impacts of large-scale wind power generation in the German power system and effects of integration measures : analyses with a stochastic electricity market model(2012) Hasche, Bernhard; Voß, Alfred (Prof.)A strong increase of onshore and offshore wind power capacities is an official political target in Germany and other countries. The wind energy shares therefore rise in many power systems. Wind power generation has other characteristics than the power generation by conventional power plants. The wind is a natural resource that is fluctuating. The meteorological dependency leads to a limited predictability of the available power. A third aspect is the concentration of wind farms at locations with high wind yields as in the North of Germany. From a methodological point of view, the thesis focuses on the analysis of the three aspects with regard to the power system operation and the development of related modelling approaches. This especially refers to the application of a stochastic optimization model for the system analysis and to the simulation of wind power generation and wind power forecasts. The application orientated focus is on a scenario analysis of the German power system in 2020. The analysis aims at the identification of promising system adaptations that lead to an improved wind power integration and a more efficient power system operation. Before the model presentation, the importance of the three aspects above is discussed giving the basics for the latter modelling. It is shown that the residual load fluctuations are increased by the wind power generation, especially if they are related to the residual load levels. The flexibility of thermal power plants is also regarded here. An analysis of operational uncertainties shows the importance of wind power forecast errors in relation to load forecast errors. The DC load flow model and characteristics of the transmission grid are explained. A stochastic market model is presented that allows an integrative analysis of the wind power integration. One characteristic of the optimization model is the application of a rolling planning so that forecast errors can be specifically considered. A main modification of the model compared to earlier model versions is given by the representation of grid constraints. A grid reduction approach is developed that reduces the transmission grid to a simplified structure that is applied in the market model. The grid reduction approach is based on a comparison of DC load flow solutions in the reduced and unreduced grid. Additionally, an approach for the calculation of tertiary reserves is given. The approach considers the wind forecast quality and combines probabilistic elements with an optimization. The simulation of wind power generation and forecasts combines different analyses and methods. General quantitative relations between the variability of wind power generation and the geographical region size are derived. The equations are applied in the simulation of wind power generation that is based on adapted wind power curves. The adapted power curves consider regional smoothing effects in the transformation of wind speed to wind power. The simulation results reflect the high variability of the concentrated offshore wind power. For the simulation of the wind power forecasts, a scenario generation method based on moment matching is presented that allows simulating non Gaussian distributed forecast errors and their correlations. The results of a statistical analysis of measured forecast errors are used in the simulation. An empirical relation between error correlation and geographical distance is for example given. The German forecast quality that is simulated for 2020 assuming an improvement of forecasting by 20% is, related to the installed capacity, similar to the one of today due to the high spatial concentration of the offshore capacities. For the scenario analysis of the power system in 2020, the power plant portfolios of twelve German regions and other parameters are derived based on different sources. This includes reserve requirement values and reduced grid parameters that are calculated by the methods mentioned above. The results show that, in the regarded scenario, 3% of the yearly wind energy cannot be integrated into the system. They are curtailed nearly exclusively due to transmission constraints. The network congestions also lead to high differences between the regional electricity prices. The yearly costs of wind forecast errors amount to circa 180 million Euros or 1% of the operational system costs. The model results thereby indicate a large cost saving potential by risk management methods. Based on scenario modifications, integration measures related to CAES capacities, demand side management and more flexible power plants as well as infrastructural changes by grid expansions and an adapted geographical allocation of power plants are analysed. The importance of a stochastic modelling approach for the evaluation of flexibility related scenarios is shown. The comparison of the integration measures identifies infrastructural changes as most efficient system improvements whereas the benefits of CAES capacities are small. Assuming a grid without any transmission constraints, the yearly system costs are reduced by one billion Euros. A limited grid upgrade leads to 10% of this cost reduction. Similar cost savings are achieved by adapting the geographical locations of the power plants. Adjusting the generation to the grid is therefore a promising alternative to grid expansions especially considering the long processes that are involved with new transmission lines. A market design with regional electricity prices would give related incentives.Item Open Access Analyse der Einsatzpotenziale von Wärmeerzeugungstechniken in industriellen Anwendungen(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2016) Ohl, Michael; Voß, Alfred (Prof. Dr.-Ing.)Item Open Access Techno-economic analysis of an instrument mix to decarbonize the electricity sector(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2024) Gillich, Annika; Hufendiek, Kai (Prof. Dr.-Ing.)Die Politiklandschaft zur Bekämpfung des Klimawandels wird zunehmend komplexer und damit auch ihre Analyse. Diese Arbeit liefert einen Beitrag zur Bewältigung dieser Aufgabe, indem drei Kerninstrumente zur Dekarbonisierung des Stromsektors, nämlich CO2-Bepreisung, Förderung von erneuerbaren Energien und Kohleausstieg, systematisch bewertet werden. Dabei werden in drei Einzelanalysen ökonomische, technologische und Verteilungseffekte auf der Erzeugungsseite betrachtet, sowie Wechselwirkungen zwischen den Instrumenten. Die erste der Analysen beschäftigt sich mit ökonomischen Effekten eines Kohleausstiegs, der parallel zum EU ETS wirkt (sogenannte „overlapping policies“). Die zweite Analyse zeigt die kurzfristigen Effekte der drei Instrumente auf Marktpreise und Deckungsbeiträge einzelner Technologien auf. In der dritten Analyse wird die langfristige Rentabilität der Technologien in einem iterativen Ansatz untersucht, unter der Annahme von unzureichenden Knappheitspreisen im realen Markt. In allen drei Analysen kommt das lineare, systemkostenoptimierende Strommarktmodell E2M2 zum Einsatz, das für die jeweilige Fragestellung geeignet adaptiert wird. Die aus diesen Analysen abgeleiteten zentralen Empfehlungen für die Gestaltung eines Politikmixes im Stromsektor sind: Erstens sollte die Anzahl an Politikinstrumenten so gering wie möglich gehalten werden. Und zweitens sollte sich die Gestaltung und die Bewertung eines Instrumentenmix an dessen theoretisch optimalem Ergebnis orientieren. Die Berücksichtigung dieser Empfehlungen kann dazu beitragen, dass der Politikmix zur Dekarbonisierung des Stromsektors in Zukunft besser geeignet ist, die Klimaziele so effizient wie möglich zu erreichen.Item Open Access Discussing the actual impact of optimizing cost and GHG emission minimal charging of electric vehicles in distributed energy systems(2021) Schulz, Maximilian; Hufendiek, KaiElectric vehicles represent a promising opportunity to achieve greenhouse gas (GHG) reduction targets in the transport sector. Integrating them comprehensively into the energy System requires smart control strategies for the charging processes. In this paper we concentrate on charging processes at the end users home. From the perspective of an end user, optimizing of charging electric vehicles might strive for different targets: cost minimization of power purchase for the individual household or - as proposed more often recently - minimization of GHG emissions. These targets are sometimes competing and cannot generally be achieved at the same time as the results show. In this paper, we present approaches of considering these targets by controlling charging processes at the end users home. We investigate the influence of differently designed optimizing charging strategies for this purpose, considering the electrical purchase cost as well as the GHG emissions and compare them with the conventional uncontrolled charging strategy using the example of a representative household of a single family. Therefore, we assumed a detailed trip profile of such a household equipped with a local generation and storage system at the same time. We implemented the mentioned strategies and compare the results concerning effects on annual GHG emissions and annual energy purchase costs of the household. Regarding GHG emissions we apply a recently proposed approach by other authors based on hourly emission factors. We discuss the effectivity of this approach and derive, that there is hardly no real impact on actual GHG emissions in the overall system. As incorporating this GHG target into the objective function increases cost, we appraise such theoretical GHG target therefore counterproductive. In conclusion, we would thus like to appeal for dynamic electricity prices for decentralised energy systems, leading at the same time to cost efficient charging of electric vehicles unfolding clear incentives for end users, which is GHG friendly at the end.