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The overall aim of this PhD-thesis is to develop empirical probabilistic frameworks that help to quantify the impacts of temporal and spatial scale dependencies and model uncertainties of climate projections regarding precipitation-dependent parameters. The thesis is structured in four journal articles. Article one is the first study that analyzed climate projections from the spatially highly resolved regional climate model (RCM) ensemble EURO-CORDEX. Additionally, the significance and the robustness of the projected changes are analyzed, and improvements related to the higher horizontal resolution of the new data set are discussed. A major finding is, that RCM simulations provide higher daily precipitation intensities, which are missing in the global climate model (GCM) simulations, and that they show a significantly different climate change of daily precipitation intensities with a smoother shift from low towards high intensities. The second article elaborates on impacts of temporal and spatial aggregation on extreme precipitation intensities. By combining radar data with cloud observations, the different temporal and spatial scaling behavior of stratiform and convective type precipitation events can be analyzed for the first time. The separation between convective and stratiform type events also allows to quantify the contribution of convective events to the extremes. Further, it is shown that temporal averaging has similar effects on the precipitation distribution as spatial averaging. Associated pairs of temporal and spatial resolutions that show comparable intensity distributions are identified. Using precipitation data from radar observations, a gauge station network and a spatially highly resolved regional climate model, the third paper optimizes the process that finds associated temporal and spatial scales (see second article). This information is used to develop a method that adjusts point measurements to the temporal and spatial scale of a previously defined model grid. The study shows that this procedure can be used to improve bias-adjustment methods in areas with a low gauge station density. It is known that the EURO-CORDEX ensemble overestimates precipitation and shows a common cold bias in the Alpine region. The fourth article evaluates how these biases are changing the temperature distribution and the temperature dependency of precipitation-frequencies. These biases are a source of uncertainty that is not captured by the robustness tests performed in the first article. A probabilistic-decomposition-framework is developed to quantify the impact of these biases on precipitation-frequency changes and to investigate causes for the ensemble spread.
The energy sector is regarded as one of the decisive subsystems influencing the future of sustainable development. Consequently, there is a need for a comprehensive transformation of energy generation, conversion and use. The importance of building capacities for energy policy development in developing countries is bound up with the need to formulate global strategies to meet the challenges that humanity face, especially to achieve the targets manifested in the Agenda 2030 and Paris Agreement. The aim of this research is to better understand how to empower marginalised key societal actors, co-produce alternative discourses about energy futures and articulate those discourses to influence policy change within a context of illiberal democracies in Latin America. The research concerns the design, function and effectiveness of scientifically grounded participatory process, which has been justified theoretically and tested empirically. The process presupposes theoretical perspectives relating to theory, method and empirical application. The first draws on theories of sustainability transition and transformation, including transition management. The second draws on ideas taken from the knowledge co-production and transdisciplinary sustainability research. The empirical application, concerns the implementation of a Transdisciplinary Transition Management Arena (TTMA) and its effectiveness, measured by potential for the co-production of knowledge and for stimulating collective action. As result of the process, a conceptual model of the energy system, long-term visions and transformation strategies were developed. The TTMA processes demonstrated that cross-sectoral and inter-institutional, combined efforts, can help actors visualize possible, future alternatives for sustainable energy development and how to realize such alternatives. The structures provided were helpful for the emergence and empowerment of new sustainable-energy-transition coalitions in both Ecuador and Peru. Chapter 1 describes the general context in which this scientific project is developed and presents a synthesis of the processes and its main outcomes. The research results are described in detail in the scientific papers presented in chapters 2,3 and 4.
Vocational integration of refugees : chances and challenges of refugee (social) entrepreneurship
(2019)
In recent years, especially since 2015, Germany and other European countries have accepted high numbers of refugees. The social and vocational integration of these refugees and of those yet to come represents a challenge. (Social) entrepreneurship is one means to achieve this goal, to fully tap into the potential of refugees and to give them a chance to make a living in host countries. This dissertation examines the potential of vocational integration of refugees through (social) entrepreneurial activities. It includes a detailed literature review and suggests possible direction in the emerging field of refugee (social) entrepreneurship. This dissertation shows that to foster refugee (social) entrepreneurship, the identification and evaluation of specific and potential needs for support is essential. Incubators in particular have a high potential for supporting refugee entrepreneurs, in part it is possible for them to address some of the challenges faced by this target group, which differ from those of locals or migrant entrepreneurs. More specifically, this dissertation aims to answer two research questions: (1) What are relevant (social) entrepreneurial concepts that can contribute to the vocational integration of refugees? (2) What are the distinct contributions of and challenges faced by refugees when it comes to their vocational integration through (social) entrepreneurial activities? Analyzing select practical cases, this dissertation has several important implications for researchers who seek to bridge the gap between academia and society in the context of refugee entrepreneurship and refugee social entrepreneurship research. The findings presented here are also relevant for practitioners, for example those working at business incubators, who aim to facilitate the vocational and social integration of refugees in general and refugees with entrepreneurial aspirations in particular.
The geographical situation of Germany considerably affects the final energy consumption of the country. Thermally intensive processes are the largest consumer of energy. In contrary, the level of energy consumed by air conditioning systems and utilized on process cooling is relatively low. Thermal energy storage systems have a high potential for a sustainable energy management, as they provide an efficient integration of thermal energy from renewables and heat recovery processes through spatial and temporal decoupling. Low temperature thermochemical energy stores based on gas-solid reactions represent appealing alternative options to sensible and latent storage technologies, in particular for heating and cooling purposes. They convert heat energy provided from renewable energy and waste heat sources into chemical energy and can effectively contribute to load balancing and CO2 mitigation. Reasonable material intrinsic energy storage density and cooling power are demanded. At present, several obstacles are associated with the implementation in full-scale reactors. Notably, the mass and heat transfer must be optimized. Limitations in the heat transport and diffusions resistances are mainly related to physical stability issues, adsorption/desorption hysteresis and volume expansion and can impact the reversibility of gas-solid reactions. The aim of this thesis was to examine the energy storage and cooling efficiency of CaCl2, MgCl2, and their physical salt mixtures as adsorbents paired with water, ethanol and methanol as adsorbates for utilization in a closed, low level energy store. Two-component composite adsorbents were engineered using a representative set of different host matrices (activated carbon, binderless zeolite NaX, expanded natural graphite, expanded vermiculite, natural clinoptiolite, and silica gel). The energetic characteristics and sorption behavior of the parent salts and modified thermochemical materials were analyzed employing TGA/DSC, TG-MS, Raman spectroscopy, and XRD. Successive discharging/charging cycles were conducted to determine the cycle stability of the storage materials. The overall performance was strongly dependent on the material combination. Increase in the partial pressure of the adsorbate accelerated the overall adsorbate uptake. From energetic perspectives the CaCl2-H2O system exhibited higher energy storage densities than the CaCl2 and MgCl2 alcoholates studied. The latter were prone to irreversible decomposition. Ethyl chloride formation was observed for MgCl2 at room and elevated temperatures. TG-MS measurements confirmed the evolution of alkyl chloride from MgCl2 ethanolates and methanolates upon heating. However, CaCl2 and its ethanolates and methanolates proved reversible and cyclable in the temperature range between 25 °C and 500 °C. All composite adsorbents achieved intermediate energy storage densities between the salt and the matrix. The use of carbonaceous matrices had a heat and mass transfer promoting effect on the reaction system CaCl2-H2O. Expanded graphite affected only moderately the adsorption/desorption of methanol onto CaCl2. CaCl2 dispersed inside zeolite 13X showed excellent adsorption kinetics towards ethanol. However, main drawback of the molecular sieve used as supporting structure was the apparent high charging temperature. Despite variations in the reactivity over thermal cycling caused by structural deterioration, composite adsorbents based on CaCl2 have a good potential as thermochemical energy storage materials for heating and cooling applications. Further research is required so that the storage media tested can meet all necessary technical requirements.