14 Externe wissenschaftliche Einrichtungen
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/15
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Item Open Access Storage technologies for the electricity transition : an analysis of actors, actor perspectives and transition pathways in Germany(2020) Frey, Ulrich J.; Wassermann, Sandra; Deissenroth-Uhrig, MarcThis article analyses actors in the storage niche during the German electricity transition. Thus, we develop a more differentiated understanding of actors and their storage activities. For that, we employ the analytical multi-level-perspective (MLP) framework to focus on interactions between old and new storage technologies. Using data from expert interviews, we investigate whether the storage pathway resembles any of the four ideal types of transition pathways for interactions between niche and regime. Through our interviews, we identify five types of actor in the storage market: Big 4 (EnBW, RWE, E.ON, Vattenfall), project developers, innovative municipal utilities, small rural municipal utilities and independent green electricity providers. For each actor, we analyse four main aspects (1) previous orientation and motivation, (2) structural strategies, (3) institutional strategies, and (4) product-related strategies. Parallel to the classification of actors, we also classify available storage technologies according to their primary field of application. We conclude that interactions between regime and niche actors are cooperative, but weak, and no specific actor type currently dominates the niche activities. Hence, applications in the storage niche are not yet ready for a larger market. In sum, our results point to a future system that is characterized by reconfiguration, not substitution or transformation of current market actors.Item Open Access Integrated multidimensional sustainability assessment of energy system transformation pathways(2021) Naegler, Tobias; Becker, Lisa; Buchgeister, Jens; Hauser, Wolfgang; Hottenroth, Heidi; Junne, Tobias; Lehr, Ulrike; Scheel, Oliver; Schmidt-Scheele, Ricarda; Simon, Sonja; Sutardhio, Claudia; Tietze, Ingela; Ulrich, Philip; Viere, Tobias; Weidlich, AnkeSustainable development embraces a broad spectrum of social, economic and ecological aspects. Thus, a sustainable transformation process of energy systems is inevitably multidimensional and needs to go beyond climate impact and cost considerations. An approach for an integrated and interdisciplinary sustainability assessment of energy system transformation pathways is presented here. It first integrates energy system modeling with a multidimensional impact assessment that focuses on life cycle-based environmental and macroeconomic impacts. Then, stakeholders’ preferences with respect to defined sustainability indicators are inquired, which are finally integrated into a comparative scenario evaluation through a multi-criteria decision analysis (MCDA), all in one consistent assessment framework. As an illustrative example, this holistic approach is applied to the sustainability assessment of ten different transformation strategies for Germany. Applying multi-criteria decision analysis reveals that both ambitious (80%) and highly ambitious (95%) carbon reduction scenarios can achieve top sustainability ranks, depending on the underlying energy transformation pathways and respective scores in other sustainability dimensions. Furthermore, this research highlights an increasingly dominant contribution of energy systems’ upstream chains on total environmental impacts, reveals rather small differences in macroeconomic effects between different scenarios and identifies the transition among societal segments and climate impact minimization as the most important stakeholder preferences.Item Open Access Impact of COVID-19 on electricity demand : deriving minimum states of system health for studies on resilience(2021) Manjunath, Smruti; Yeligeti, Madhura; Fyta, Maria; Haas, Jannik; Gils, Hans-ChristianTo assess the resilience of energy systems, i.e., the ability to recover after an unexpected shock, the system’s minimum state of service is a key input. Quantitative descriptions of such states are inherently elusive. The measures adopted by governments to contain COVID-19 have provided empirical data, which may serve as a proxy for such states of minimum service. Here, we systematize the impact of the adopted COVID-19 measures on the electricity demand. We classify the measures into three phases of increasing stringency, ranging from working from home to soft and full lockdowns, for four major electricity consuming countries of Europe. We use readily accessible data from the European Network of Transmission System Operators for Electricity as a basis. For each country and phase, we derive representative daily load profiles with hourly resolution obtained by k-medoids clustering. The analysis could unravel the influence of the different measures to the energy consumption and the differences among the four countries. It is observed that the daily peak load is considerably flattened and the total electricity consumption decreases by up to 30% under the circumstances brought about by the COVID-19 restrictions. These demand profiles are useful for the energy planning community, especially when designing future electricity systems with a focus on system resilience and a more digitalised society in terms of working from home.Item Open Access Investigation of the long‐term stability of solid oxide electrolysis stacks under pressurized conditions in exothermic steam and co‐electrolysis mode(2020) Riedel, Marc; Heddrich, Marc P.; Friedrich, K. AndreasIn this study three identically constructed ten‐layer stacks with electrolyte supported cells were tested in exothermic steam and co‐electrolysis mode at elevated pressures of 1.4 and 8 bar. Investigations during constant‐current operation at a current density of -0.5 A cm-2 and a reactant conversion of 70% over 1,000-2,000 h were carried out. The inlet gas composition for steam electrolysis was 90/10 (H2O/H2) and 63.7/31.3/3.3/1.7 (H2O/CO2/H2/CO) for co‐electrolysis operation. All stacks showed highly similar resistances at the beginning of the tests indicating a high level of accuracy and repeatability during manufacturing. The stack operated in steam electrolysis mode at 1.4 bar showed comparably low degradation of 8 mV kh-1 cell-1, whereas the stack operated at 8 bar showed an approximately four times higher degradation. The third stack was operated in co‐electrolysis mode at 1.4 and 8 bar and showed noticeably higher degradation rates than during steam electrolysis mode. The predominant increase of the ohmic resistance during operation was identified to be mainly responsible for the observed degradation of all three stacks, whereas the increase of the polarization resistances played a subordinate role. Within the post‐test analysis, noticeably high nickel depletion was observed for the stack operated at the highest pressure in steam electrolysis mode. Furthermore, partial delamination of electrodes was observed. The degradation is discussed with relation to phenomena and experimental parameters during operation.