Browsing by Author "Hufendiek, Kai (Prof. Dr.-Ing.)"

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Open Access
Analyse von Demand Side Integration im Hinblick auf eine effiziente und umweltfreundliche Energieversorgung
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2017) Steurer, Martin; Hufendiek, Kai (Prof. Dr.-Ing.)
Ziel der vorliegenden Arbeit ist die quantitative Ermittlung und Bewertung des Beitrags, den Demand Side Integration (DSI), das heißt die Flexibilisierung der Stromnachfrage, zur Erreichung klima- und energiepolitischer Zielsetzungen in Deutschland leisten kann. Dabei steht insbesondere die durch DSI realisierbare Reduktion der Systemkosten bei der Integration hoher Anteile dargebotsabhängiger erneuerbarer Stromeinspeisung und dem einhergehenden steigenden Bedarf an Flexibilität im Vordergrund. Auf Basis bestehender Untersuchungen kann zwar vermutet werden, dass hierbei Potentiale vorhanden sind. Wie groß diese vor allem im Wettbewerb mit anderen Flexibilitätsoptionen sind, ist jedoch unklar und wird durch die Dissertation beleuchtet. Dazu wird in der Arbeit ein integrierter Ansatz entwickelt, mit dem eine detaillierte, empirisch gestützte Potentialanalyse mit einer systemanalytischen Bewertung dieser Potentiale verknüpft wird. Dieser Ansatz fehlte bislang in der Literatur und wird zur Quantifizierung möglicher Systemeffekte durch DSI eingesetzt. Ergänzend dazu wird eine Untersuchung sinnvoller Weiterentwicklungen der Rahmenbedingungen für DSI in Deutschland durchgeführt.
Open Access
Implementing household heterogeneity in a multi-regional technology based energy-economic model : system analysis on distributional impacts of pan-European energy and environmental policies
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2024) Cunha Montenegro, Roland; Hufendiek, Kai (Prof. Dr.-Ing.)
The European Union (EU) set ambitious targets for the reduction of greenhouse gases until 2030 in order to achieve the 1.5C objective of the Paris Agreement. Among the measures to reach this goal, carbon pricing is a promising one as it increases the costs of polluting activities and makes the use of clean technologies more attractive. While this mechanism is already used in energy-intensive sectors, such as energy conversion and chemicals, its application on the remaining sectors of the economy is treated with caution, since economical and social outputs are unclear and might jeopardize the long-term will to cut emissions. This work aims to add on understanding the socio-economic effects of a multi-regional carbon pricing scheme with focus on the household sector. It proposes that each EU Member State implements a national cap-and-trade system, where the carbon price is defined according to supply and demand of CO2 certificates. Furthermore, four revenue redistribution mechanisms are explored: reduced consumption taxes, reduced labor taxes, equal per capita redistribution and per capita redistribution according to income levels. For the analysis, a global Computable General Equilibrium model is expanded to represent distinct income groups. This feature allows for the model to assess not only economic effects, as GDP development, but also social implications, such as income distribution and tax burden across different households. Finally, it is possible to assess whether the analyzed policies lead to a double dividend, in which emissions are reduced and GDP increases, and even a social dividend, characterized by decreased income inequality. The results indicate that no revenue redistribution scheme lead to significant improvement in GDP, but each one helps decreasing certain negative aspects of pricing carbon. Reducing consumption and labor taxes lead to the highest employment levels among the analyzed policies, while per capita redistribution helps decreasing income inequality. Additionally, consumption of electricity and fossil-fuels varies according to redistribution mechanism, which is an important input for multi-model analysis.
Open Access
Integrating environmental, macro-economic, and uncertainty aspects into energy system analysis
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2023) Korkmaz, Pinar; Hufendiek, Kai (Prof. Dr.-Ing.)
Open Access
Interdependencies of prosumer households with the overall energy system with regard to system efficiency and distributional effects
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2024) Schick, Christoph; Hufendiek, Kai (Prof. Dr.-Ing.)
Open Access
Modellierung und Bewertung von Energieautarkie in städtischen Energiesystemen
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2024) Brodecki, Lukasz; Hufendiek, Kai (Prof. Dr.-Ing.)
Die Energiewende und der damit einhergehende Ausbau Erneuerbarer Energien sind die bestimmenden Faktoren für die zunehmende Dezentralisierung des Energiesystems. Demnach können steigende Energieautarkiebestreben auf lokaler Ebene einen bedeutenden Anteil zur Transformation des Energiesystems haben. Gleichzeitig wurden die Einflüsse von Autarkiebewegungen auf das Energieversorgungssystem noch nicht hinreichend durchleuchtet. Im Zuge dieser Arbeit werden die Auswirkungen der Energieautarkie auf städtische Energieversorgungsstrukturen modelltechnisch untersucht und unter technischen, ökonomischen sowie ökologischen Gesichtspunkten bewertet. Ausgehend von der Leitfrage erfolgt die Schließung von Definitionslücken der Energieautarkie in der Literatur und die Erarbeitung einer einheitlichen und vollständigen Begriffsdefinition. Darauf aufbauend werden zu schließende Forschungslücken hinsichtlich der Methoden zur modelltechnischen Abbildung von Energieautarkie identifiziert. Zentraler Aspekt der Arbeit ist die Entwicklung methodischer Ansätze zur integralen Abbildung von Energieautarkie, die neben methodischen Änderungen auch inhaltliche Weiterentwicklungen des linearen Optimierungsmodel TIMES Local erfordert. Die Ergebnisse zeigen, dass die Erreichung einer bilanziellen sowie lastgerechten Energieautarkie in einem städtischen Energiesystem möglich ist. Grundlage hoher Autarkiegrade sind eine tiefgreifende Elektrifizierung der Versorgungsstruktur sowie der Einsatz von Flexibilitätsoptionen. Autarkiebestreben und klimapolitische Ziele sind bis zu bestimmten Autarkiegraden kongruent, führen jedoch zu einem veränderten Investitionsverhalten und Anlageneinsatz. Durch die Analyse und methodischen Weiterentwicklungen können politische Rahmenbedingungen für eine autarkiegestützte Dekarbonisierung städtischer Energiesysteme abgeleitet werden, während potenzielle Fehlanreize identifiziert und vermieden werden können. Die Methodik und die modelltechnischen Grundlagen zur Abbildung von Energieautarkie sind dabei auf variable Fragestellungen und weitere Modellansätze übertragbar.
Open Access
Modelling the energy yield of bifacial photovoltaic plants and their integration into European power supply systems
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2022) Chudinzow, Dimitrij; Hufendiek, Kai (Prof. Dr.-Ing.)
Bifacial photovoltaic systems (B-PV) offer the advantage over conventional, monofacial photovoltaic systems (C-PV) that the irradiation hitting the back can also be converted into electricity. Thanks to this property, B-PV offer the possibility of significantly increasing the energy yield and reducing the cost of electricity. Furthermore, vertically installed bifacial PV systems (VBPV) facing east and west can achieve a generation profile complementary to C-PV, which can help to increase the economic efficiency of market-oriented PV systems and reduce integration costs in national power supply systems. Despite these promising features, B-PV has long played a minor role in research, development and application, leaving knowledge gaps in the areas of “energy yield simulation”, “field design” and “integration into power supply systems”. The present thesis contributes to closing these knowledge gaps. In the first step, the state of the art in energy yield modelling of B-PV as of 2016 was analysed. It was found that the adequate modelling of cast ground shadows, the irradiation absorbed from the front and the back, as well as the yield-reducing effects of the module rows on each other, represents a knowledge gap. Using a newly developed energy yield model, methods were developed to address this knowledge gap. This was essentially achieved by combining three-dimensional modelling of the PV system and methods from the field of irradiation exchange. This approach made it possible to quantify and classify the influence of important irradiation and installation parameters on the energy yield. In addition, a breakdown of the total absorbed irradiation into eight components became possible, which allows a site-dependent identification of the most important irradiation contributions. As a result, it was shown, among other things, that the presence of ground shadows can reduce the backside contribution to electricity generation by almost 30 % and the total annual electricity generation by up to 4 %. This illustrates the importance of thorough modelling of ground-reflected irradiance for a sound energy yield prediction. While decades of experience in field design of C-PV have led to reliable design guidelines on how to achieve minimum cost of electricity, this level of knowledge is not yet available to the same extent for B-PV. To contribute closing this knowledge gap, the second step was to use the newly developed model to investigate for eight European sites how different installation parameters affect the energy yield and cost of electricity of non-tracking and single-axis tracking B-PV. From this, general recommendations for the field design were derived, depending on latitude and irradiation conditions. The results showed, among other things, that with increasing latitude of the investigated site, an increase in the row spacing leads to an ever higher energy yield gain. If the energy yield is to be achieved by brightening the soil (e.g. with bright gravel), which is associated with additional costs, a reduction in the electricity generation costs is possible with a suitable overall configuration of the PV field. This illustrates that the complex interactions of radiation absorption must always be investigated holistically in order to find the cost optimum. A validation of the simulation model showed that the angle-dependent absorption of irradiation on the front side is well represented by the simulation model. Only at a tilt angle of 90° do larger deviations occur. The angle-dependent electricity generation (front + rear side) is also well captured by the model, with larger deviations occurring at a tilt angle of 0° (module is parallel to the ground). At cloudy weather, the model tends to overestimate the electricity generation by approx. 5 %, at sunnier weather the electricity generation is underpredicted by 10 %-15 %. The highest underprediction of generated electricity was observed at a tilt angle of 0° with a 20 % deviation. National power supply systems with high shares of installed C-PV capacity face the challenge of nearly simultaneous power generation from these systems because they are generally oriented towards the equator. This results in a generation peak at midday, while in the mornings and afternoons electricity generation is usually significantly lower. On the one hand, this simultaneity leads to decreasing electricity prices on the stock exchange, which endangers the profitability of PV systems. On the other hand, the total costs of power supply systems increase due to the need to maintain power plant reserves and electricity storage. VBPV enables feed-in profiles that have a peak in the morning and a peak in the afternoon. Consequently, in the third step, it was investigated which energetic and economic advantages could result from the use of VBPV compared to C-PV. The economic analyses from a business perspective were carried out for twelve locations in four European countries, while the cost-reducing effects in a power supply system were investigated with the help of a cost-minimising electricity market model using Germany as an example. It could be shown that above a latitude of 50°, VBPV always has a higher annual electricity generation than C-PV. An analysis of historical electricity prices in Germany showed that although C-PV always had a higher net present value, the difference to VBPV constantly decreased with decreasing electricity prices, which indicates an increasing competitiveness of VBPV. At the system level, VBPV was found to play an essential role in a cost-minimal electricity system with a high share of renewables and a high CO2-reduction. In the most ambitious of the climate scenarios investigated, VBPV would account for about 70 % of the total installed PV capacity and enable an annual system cost reduction of about 0.6 %.
Open Access
System analysis of the significance of energy poverty on household energy use and emissions in Germany
(Stuttgart : Universität Stuttgart, Institut für Energiewirtschaft und Rationelle Energieanwendung, 2022) Dobbins, Audrey; Hufendiek, Kai (Prof. Dr.-Ing.)
The energy transition in Germany will increase renewable energy and energy efficiency with the aim to decarbonise the energy system. Households represent a third of the final energy consumption and as such have a crucial role to play by undertaking investments in the household energy infrastructure (building insulation, heating systems, and appliances). However, limited income influences how some households are able to engage with and benefit from the transforming energy system given that the majority of households lack either the sufficient disposable income to afford the high upfront costs of investments, or the decision-making power to undertake meaningful investments. At the same time, it is estimated that 11-21% of the German population already experiences energy poverty, and is on the rise. Yet the phenomenon is not recognised by the government as an issue requiring a tailored response. Current energy policy is based on modelling assessments which assume a homogenous population, which can underestimate the impact on lower income households and overestimate the possible contributions from this sector towards achieving the overall objectives of the energy transition. This research provides an empirical basis for recognising the significance of energy poverty outside of the current “vulnerable consumers” lens and within the energy transition process. Based on the TIMES-Germany model, the TIMES-Actors-Model-Households was expanded to account for the differentiated needs and capabilities of the population. The suitability of the method developed are demonstrated through several scenarios to explore issues relevant to energy vulnerable households, such as access and affordability. The results showed that disaggregation is a useful methodology to assess the differentiated energy needs of households based on socio-economic parameters, but highlighted that disaggregation alone is not enough to represent the lack of financial capacity of households. The incorporation of budget constraints is a critical methodological inclusion to assess the significance of energy poverty in the energy system. This enabled an analysis of the impacts of policies designed to support lower income households, such as investment or consumption subsidies or the effects of carbon taxes, or schemes to redistribute funding. Another result facilitated through this method is the estimation of the supressed demand experienced as a key indicator of the energy welfare of households. This methodology provides a platform to support the analysis of a differentiated policy response – effectively strengthening the opportunity to achieve the desired active participation in the energy transition and the energy welfare of households.
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.
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.)