14 Externe wissenschaftliche Einrichtungen
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Item Open Access Enhancement of the REMix energy system model : global renewable energy potentials, optimized power plant siting and scenario validation(2014) Stetter, Daniel; Müller-Steinhagen, Hans (Prof. Dr.-Ing. habil. DEng/Auckland)As electricity generation based on volatile renewable resources is subject to fluctuations, data with high temporal and spatial resolution on their availability is indispensable for integrating large shares of renewable capacities into energy infrastructures. The scope of the present doctoral thesis is to enhance the existing energy modelling environment REMix in terms of (i.) extending the geographic coverage of the potential assessment tool REMix-EnDaT from a European to a global scale, (ii.) adding a new plant siting optimization module REMix-PlaSMo, capable of assessing siting effects of renewable power plants on the portfolio output and (iii.) adding a new alternating current power transmission model between 30 European countries and CSP electricity imports from power plants located in North Africa and the Middle East via high voltage direct current links into the module REMix-OptiMo. With respect to the global potential assessment tool, a thorough investigation is carried out creating an hourly global inventory of the theoretical potentials of the major renewable resources solar irradiance, wind speed and river discharge at a spatial resolution of 0.45°x0.45°. A detailed global land use analysis determines eligible sites for the installation of renewable power plants. Detailed power plant models for PV, CSP, wind and hydro power allow for the assessment of power output, cost per kWh and respective full load hours taking into account the theoretical potentials, technological as well as economic data. The so-obtined tool REMix-EnDaT can be used as follows: First, as an assessment tool for arbitrary geographic locations, countries or world regions, deriving either site-specific or aggregated installable capacities, cost as well as full load hour potentials. Second, as a tool providing input data such as installable capacities and hourly renewable electricity generation for further assessments using the modules REMix-PlasMo and OptiMo. The plant siting tool REMix-PlaSMo yields results as to where the volatile power technologies photovoltaics and wind are to be located within a country in order to gain distinct effects on their aggregated power output. Three different modes are implemented: (a.) Optimized plant siting in order to obtain the cheapest generation cost, (b.) a minimization of the photovoltaic and wind portfolio output variance and (c.) a minimization of the residual load variance. The third fundamental addition to the REMix model is the amendment of the module REMix-OptiMo with a new power transmission model based on the DC load flow approximation. Moreover, electricity imports originating from concentrating solar power plants located in North Africa and the Middle East are now feasible. All of the new capabilities and extensions of REMix are employed in three case studies: In case study 1, using the module REMix-EnDaT, a global potential assessment is carried out for 10 OECD world regions, deriving installable capacities, cost and full load hours for PV, CSP, wind and hydro power. According to the latter, photovoltaics will represent the cheapest technology in 2050, an average of 1634 full load hours could lead to an electricity generation potential of some 5500 PWh. Although CSP also taps solar irradiance, restrictions in terms of suitable sites for erecting power plants are more severe. For that reason, the maximum potential amounts to some 1500 PWh. However, thermal energy storage can be used, which, according to this assessment, could lead to 5400 hours of full load operation. Onshore wind power could tap a potential of 717 PWh by 2050 with an average of 2200 full load hours while offshore, wind power plants could achieve a total power generation of 224 PWh with an average of 3000 full load hours. The electricity generation potential of hydro power exceeds 3 PWh, 4600 full load hours of operation are reached on average. In case study 2, using the module REMix-PlaSMo, an assessment for Morocco is carried out as to determine limits of volatile power generation in portfolios approaching full supply based on renewable power. The volatile generation technologies are strategically sited at specific locations to take advantage of available resources conditions. It could be shown that the cost optimal share of volatile power generation without considering storage or transmission grid extensions is one third. Moreover, the average power generation cost using a portfolio consisting of PV, CSP, wind and hydro power can be stabilized at about 10 €ct/kWh by the year 2050. In case study 3, using the module REMix-OptiMo, a validation of a TRANS-CSP scenario based upon high shares of renewable power generation is carried out. The optimization is conducted on an hourly basis using a least cost approach, thereby investigating if and how demand is met during each hour of the investigated year. It could be shown, that the assumed load can safely be met in all countries for each hour using the scenario's power plant portfolio. Furthermore, it was proven that dispatchable renewable power generation, in particular CSP imports to Europe, have a system stabilizing effect. Using the suggested concept, the utilization of the transfer capacities between countries would decrease until 2050.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 Balancing of intermittent renewable power generation by demand response and thermal energy storage(2015) Gils, Hans Christian; Thess, André (Prof. Dr. rer. nat.)Balancing of intermittent renewable power generation from wind and solar energy is one of the central challenges within the energy system transformation towards a more sustainable supply. This work addresses the potential role of flexible electric loads and power-controlled operation of combined heat and power (CHP) plants in meeting increasing balancing needs in Germany. It conducts an enhancement of the cross-sectoral REMix model, which is designed for the preparation and assessment of energy supply scenarios based on a system representation in high spatial and temporal resolution. The analysis is composed of three fundamental parts. The first part is dedicated to the quantification of theoretical potentials for demand response (DR), district heating (DH) and industrial CHP in Europe. Special attention is given to the geographic distribution of potentials, as well as the derivation of hourly heat and electricity demand profiles. In the second part, the linear optimization model within REMix is extended by DR and the heating sector, enabling economic assessments of the balancing function of flexible electric loads and power-controlled heat supply. In the third part, REMix is applied to assess the future energy supply in Germany, making use of the model enhancements and identified potentials. In order to account for different renewable energy (RE) and grid capacity development paths, as well as transport and heat sector structures, nine scenarios are considered. For each scenario, least-cost dimensioning and operation of DR capacities, as well as heat supply systems are evaluated. According to the REMix results, the application of DR is mostly limited to short time peak shaving of the residual load. This implies that its focus is on the provision of power, not energy. As a consequence of different cost structures, the exploitation of available DR potentials is attributed almost exclusively to industrial and commercial sector loads, whereas those in the residential sector are hardly accessed. The model results indicate that the temporal availability of DR potentials, as well as their characteristic intervention and shift times are particularly suited for a combination with PV power generation. In the simulations, power-controlled heat supply has proven to be an effective measure to increase RE integration. It is achieved by a modified operation pattern of CHP and - to a lower extent - heat pumps (HP) enabled by thermal energy storage (TES) on the one hand, and an utilization of surplus power for heating purposes on the other. Due to the greater potential and thus longer storage times of TES, as well as the comparatively low investment costs of electric boilers, an enhanced coupling between power and heat sector is found to be especially favorable in combination with wind power utilization. Load shifting across all sectors provides substantial amounts of positive balancing power, which can substitute other firm generation capacity. The highest load reduction is achieved by controlled electric vehicle charging, lower contributions come from adjusted HP operation and other DR. As a consequence of higher RE integration, load shifting and power-controlled heat supply can contribute substantially to CO2 emission reductions in Germany. However, this is only the case if the additional balancing potentials are not applied as well for an economically motivated shift in power generation from low-emitting to high-emitting fuels. Furthermore, load flexibility and enhanced power-heat-coupling can enable energy supply cost reductions, arising from the substitution of back-up power plant capacity on the one hand, and a more cost-efficient power and heat supply on the other. The model application reveals that electric load shifting and power-controlled CHP operation are not competing but complementary measures in the realization of higher RE integration and lower back-up capacity demand. Negative interferences between both balancing options are found to be very small. On the contrary, they even promote each other, for example in the reduction of RE curtailments. Based on the REMix results it can be concluded that both DR and power-controlled heat supply enabled by TES are important elements in a future German energy system mainly relying on renewable sources.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 Fernübertragung regelbarer Solarenergie von Nordafrika nach Mitteleuropa(2013) Hess, DenisDie Forschungsergebnisse regelbarer Solarstromimporte zeigen ein wissenschaftliches Bild, welches Menschen auf kommunaler Ebene in vier Nationen mit Hilfe von erneuerbaren Energien verbinden kann. Die rein wissenschaftliche Modellstudie umfasst die integrale Betrachtung eines regelbaren Solarstromtransfers von Marokko nach Baden-Württemberg. Hierbei wird eine Analyse von gesellschaftlichen, technischen, ökonomischen und ökologischen Aspekten dargestellt. Es wird gezeigt welche politischen Rahmenbedingungen gelten. Anhand des Beispiels Baden-Württembergs wird der Strombedarf aus erneuerbaren Energien mit bis zu 95% analysiert. Als Importmöglichkeit von gut regelbaren erneuerbaren Energien als ideale Ergänzung zu den heimischen fluktuierenden Energien bietet sich elektrischer Strom aus solaren Dampfkraftwerken in Nordafrika an. Für die Fernübertragung wird eine Hochspannungs-Gleichstrom-Übertragung verwendet, welche verlustarm und kosteneffizient den Strom transportiert. Eine Kostenrechnung stellt die Gesamtkosten von 11,7 €Cent/kWh und die potentielle Ersparnis von bis zu 3,8 Mrd. € gegenüber regelbaren fossilen Energien da. Für die Umsetzung werden Bürgerbeteiligungskonzepte erläutert und Strategien für die Finanzierung gezeigt. Eine internationale genossenschaftliche Projektstruktur soll den Rahmen für eine Umsetzung als Bürgerprojekt mit demokratischer Legitimation auf kommunaler Ebene sichern. Dauerhaft Betroffene werden so zu dauerhaft Beteiligten und ggf. sogar zu Initiatoren des Projekts. Hierdurch entsteht eine Partnerschaft mehrerer Nationen auf kommunaler Ebene, die durch politische Arbeit auf Regierungsebene unterstützt werden kann.