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As modern society progresses, waste treatment becomes a pressing issue. Not only are global waste amounts increasing, but there is also an unmet demand for sustainable materials (e.g. bioplastics). By identifying and developing processes, which efficiently treat waste while simultaneously generating sustainable materials, potentially both these issues might be alleviated. Following this line of thought, this dissertation focuses on procedures for treatment of the organic fraction of waste. Organic waste is a suitable starting material for microbial fermentation, where carbohydrates are converted to smaller molecules, such as ethanol, acetic acid, and lactic acid. Being the monomer of the thermoplastic poly-lactic acid, lactic acid is of particular interest with regard to bioplastics production and was selected as target compound for this dissertation. Organic waste acted as substrate for non-sterile batch and continuous fermentations. Fermentations were initiated with inoculum of Streptococcus sp. or with indigenous consortium alone. During batch mode, concentration, yield, and productivity reached maximum values of 50 g L−1, 63%, and 2.93 g L−1 h −1. During continuous operation at a dilution rate of 0.44 d−1, concentration and yield were increased to 69 g L−1 and 86%, respectively, while productivity was lowered to 1.27 g L−1 h −1 . To fully exploit the nutrients present in organic waste, phosphate recovery was analyzed using seashells as adsorbent. Furthermore, the pattern of the indigenous consortium was monitored. Evidently, a very efficient Enterococcus strain tended to dominate the indigenous consortium during fermentation. The isolation and cultivation of this consortium gave a very potent inoculum. In comparison to the non-inoculated fermentation of a different organic waste batch, addition of this inoculum lead to an improved fermentation performance. Lactic acid yield, concentration, and molar selectivity could be increased from 38% to 51%, 49 g L−1 to 65 g L−1, and 46% to 86%, respectively. Eventually, fermentation process data was used to perform techno-economic analysis proposing a waste treatment plant with different catchment area sizes ranging from 50,000 to 1,000,000 people. Economically profitable scenarios for both batch and continuous operation could be identified for a community with as few as 100,000 inhabitants. With the experimental data, as well as techno-economic calculations presented in this dissertation, a profound contribution to sustainable waste treatment and material production was made.
Existing institutions no longer appear to be sufficiently capable to deal with the complexity and uncertainty associated with the wicked problem of sustainability. Achieving the required sustainability transformation will thus require purposeful reform of existing institutional frameworks. However, existing research on the governance of sustainability of sustainability transformations has strongly focused on innovation and the more "creative" aspects of these processes, blinding our view to the fact that they go hand with the failure, decline or dismantling of institutions that are no longer considered functional or desirable. This doctoral dissertation thus seeks to better understand how institutional failure and decline can contribute productively to sustainability transformations and how such dynamics in institutional arrangements can serve to restructure existing institutional systems. A systematic review of the conceptual literature served to provide a concise synthesis of the research on "failure" and "decline" in the institutional literature, providing important first insights into their potentially productive functions. This was followed up by an archetype analysis of the productive functions of failure and decline, drawing on a wide range of literatures. This research identified five archetypical pathways: (1) crises triggering institutional adaptations toward sustainability, (2) systematic learning from failure and breakdown, (3) the purposeful destabilisation of unsustainable institutions, (4) making a virtue of inevitable decline, and (5) active and reflective decision making in the face of decline instead of leaving it to chance. Empirical case studies looking at the German energy transition and efforts to phase out coal in the Powering Past Coal Alliance served to provide more insights on (a) how to effectively harness "windows of opportunity" for change, and (b) the governance mechanisms used by governments to actively remove institutions. Results indicate that the lock-in of existing technologies, regulations and practices can throw up important obstacles for sustainability transformations. The intentional or unintentional destabilisation of the status quo may thus be required to enable healthy renewal within a system. This process required active and reflective management to avoid the irreversible loss of desirable institutional elements. Instruments such as "sunset clauses" and "experimental legislation" may serve as important tools to learn through "trial and error", whilst limiting the possible damage done by failure. Focusing on the subject of scale, this analysis finds that the level at which failure occurs is likely to determine the degree of change that can be achieved. Failures at the policy-level are most likely to merely lead to changes to the tools and instruments used by policy makers. This research thus suggests that failures on the polity- and political level may be required to achieve transformative changes to existing power structures, belief-systems and paradigms. Finally, this research briefly touches on the role of actor and agency in the governance of sustainabilitytransformations through failure and decline. It finds that actors may play an important role in causing a system or one of its elements to fail and in shaping the way events are come to be perceived.
"Reallabore" erleben als junges Format transformativer Nachhaltigkeitsforschung gegenwärtig eine beeindruckende Konjunktur. Die Dissertation arbeitet den Reallabor‐Ansatz aus Perspektive der transdisziplinären Forschung methodisch aus. Die Basis hierfür bildet die Erfahrung mit dem Auf‐ und Ausbau von einem der ersten Reallabore in Deutschland: Das langfristig ausgelegte "Quartier Zukunft - Labor Stadt" in Karlsruhe transformiert in Kooperation mit der Zivilgesellschaft ein Quartier modellhaft in einen nachhaltigeren Lebensraum. Es setzt dabei gleichermaßen auf Bildung, Forschung und Praxis. Die vorgelegten Artikel der kumulativen Dissertation bilden verschiedene Stadien der Entwicklung der Reallaborforschung und der methodologischen Reflexion ab. Die ersten beiden Texte entwickeln eine praxisnahe Definition und ordnen Reallabore ein in verwandte Diskurse. Die folgenden beiden Artikel stammen aus der beginnenden Stabilisierung des Reallabordiskurses. Der eine stellt Ziele und Designprinzipien für Reallabore als Rahmen transformativer und transdisziplinärer Forschung dar, der zweite greift aktuelle Diskussionen um Lernprozesse konzeptionell auf. Die letzten zwei Artikel fokussieren auf die Ebene der Projekte im Reallabor am Beispiel der Transformativen Projektseminare, einmal in analytischer Perspektive, einmal in methodisch‐didaktischer. Der Rahmentext abstrahiert die Ergebnisse der zuvor publizierten Artikel entlang dreier Forschungsfragen: Was ist neu am Reallabor‐Ansatz? Welches Potenzial hat ein Reallabor für transdisziplinäre Forschung? Und welche Rolle spielt Lernen im Reallabor? Die methodologische Reflexion führt zu einem Verständnis von Reallaboren als Format zwischen Urban Living Labs und Transition Labs, das sich gegenüber diesen insbesondere durch Langfristigkeit, Bildungsziele und eine klare Trennung zwischen Labor und Experimenten auszeichnet. Aus der kritischen Auseinandersetzung mit Reallaboren wird eine doppelte Bezugnahme auf Transdisziplinarität herausgearbeitet, einerseits als Infrastruktur für transdisziplinäre Projekte, andererseits als in sich transdisziplinäres Unterfangen. Ausgehend von dieser Unterscheidung wird ein Vorschlag gemacht, an welche experimentellen Methodologien jenseits der klassisch‐naturwissenschaftlichen die transdisziplinäre Forschung, die bislang kaum experimentell arbeitet, anknüpfen kann. Das Reallabor unterstützt solche Experimente durch einen Rahmen aus materieller Infrastruktur, durch Kompetenzen der Beteiligten, durch Wissensbestände und soziale Vernetzung. Die Vernetzung über Projektgrenzen hinweg, ein weiteres wesentliches Charakteristikum eines Reallabors, dient dazu, parallele Experimente zu vernetzen und iterative Lernzyklen zu unterstützen. Diese Aspekte werden verbunden zum "Apfelmodell" transdisziplinärer Forschung im Reallabor, in dem das Reallabor als doppeltes Bindeglied fungiert, einerseits zwischen internen und externen Lernzyklen, und andererseits zwischen wissenschaftlichen, bildungsorientierten und praktischen. Durch die Interpretation der Abläufe im Reallabor als Lernprozesse wird ein Anschluss an Bildungsprozesse auf unterschiedlichen Skalen möglich. Neben Lernprozessen im Reallabor als Lernumgebung lässt sich das Reallabor als lernende Institution und als Kristallisationspunkt gesellschaftlicher Lernprozesse verstehen. Das Apfelmodell kann gleichermaßen im Kontext theoretischer Fragen im Transdisziplinaritätsdiskurs herangezogen werden als auch praktischen Zwecken dienen, insbesondere in der Planung von Reallaboren, in der quervernetzten Konzeption von Projekten darin, in der Evaluation und in der Kommunikation.
Wind energy is expected to become the largest source of electricity generation in Europe's future energy mix. As a consequence, future electricity generation will be exposed to an increasing degree to weather and climate. With planning and operational lifetimes of wind energy infrastructure reaching climate time scales, adaptation to changing climate conditions is of relevance to support secure and sustainable energy supply. Premise for success of wind energy projects is the ability to service financial obligations over the project lifetime. Though, revenues(viaelectricity generation) are exposed to changing climate conditions affecting the wind resource, operating conditions or hazardous events interfering with the wind energy infrastructure. For the first time, a procedure is presented to assess such climate change impacts specifically for wind energy financing. At first, a generalised financing chain for wind energy is prepared to (qualitatively) trace the exposure of individual cost elements to physical climate change. In this regard, the revenue through wind power production is identified as the essential component within wind energy financing being exposed to changing climate conditions. This implies the wind resource to be of crucial interest for an assessment of climate change impacts on the financing of wind energy. Therefore, secondly, a novel high-resolution experimental modelling framework with the non-hydrostatic extension of the regional climate model REMO is set up to generate physically consistent climate and climate change information of the wind resource across wind turbine operating altitudes. With this setup, enhanced simulated intra-annual and inter-annual variability across the lower planetary boundary layer is achieved, being beneficial for wind energy applications, compared to state-of-the-art regional climate model configurations. In addition, surrogate climate change experiments with this setup disclose vertical wind speed changes in the lower planetary boundary layer to be indirectly affected by temperature changes through thermodynamically-induced atmospheric stability alterations. Moreover, air density changes are identified to occasionally exceed the net impact of wind energy density changes originating from changes in wind speed. This supports the consideration of air density information (in addition to wind speed) for wind energy yiel assumptions. Thirdly, the generated climate and climate change information of the wind resource are transferred to a simplified but fully-fledged financial model to assess the financial risk of wind energy project financing with respect to changing climate conditions. Sensitivity experiments for an imaginary offshore wind farm located in the German Bight reveal the long-term profitability of wind energy project financing not to be substantially affected by changing wind resource conditions, but incidents with insufficient servicing of financial obligations experience changes exceeding -10% to 14%. The integration of wind energy-specific climate and climate change information into existing financial risk assessment procedures would illustrate a valuable contribution to enable climate change adaptation for wind energy.
In response to the challenges of the energy transition, the German electricity network is subjected to a process of substantial transformation. Considering the long latency periods and lifetimes of electricity grid infrastructure projects, it is more cost-efficient to combine this need for transformation with the need to adapt the grid to future climate conditions. This study proposes the spatially varying risk of electricity grid outages as a guiding principle to determine optimal levels of security of electricity supply. Therefore, not only projections of future changes in the likelihood of impacts on the grid infrastructure were analyzed, but also the monetary consequences of an interruption. Since the windthrow of trees was identified a major source for atmospherically induced grid outages, a windthrow index was developed, to regionally assess the climatic conditions for windthrow. Further, a concept referred to as Value of Lost Grid was proposed to quantify the impacts related to interruptions of the distribution grid. In combination, the two approaches enabled to identify grid entities, which are of comparably high economic value and subjected to a comparably high likelihood of windthrow under future climate conditions. These are primarily located in the mid-range mountain areas of North-Rhine Westphalia, Baden-Württemberg and Bavaria. In comparison to other areas of less risk, the higher risk in these areas should be reflected in comparably more resilient network structures, such as buried lines instead of overheadlines, or more comprehensive efforts to prevent grid interruptions, such as structural reinforcements of pylons or improved vegetation management along the power lines. In addition, the outcomes provide the basis for a selection of regions which should be subjected to a more regionally focused analysis inquiring spatial differences (with respect to the identified coincidence of high windthrow likelihoods and high economic importance of the grid) among individual power lines or sections of a distribution network.
Thermal energy storage systems have a high potential for a sustainable energy management. 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. 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.
To improve the properties of thermochemical heat storage materials, salt mixtures were evaluated for their heat storage capacity and cycle stability as part of the innovation incubator project "Thermochemical battery" of the Leuphana university Lüneburg. Based on naturally occurring compound minerals, 16 sulfates, 18 chlorides and 5 chloride multi-mixtures, 18 bromides and 5 intermixtures between sulfates, chlorides and bromides were synthesized either from liquid solution or by dry mixing for TGA/DSC screening before continuing the heat storage evaluation with five different measurement setups at a laboratory scale. The TGA/DSC analysis served as a screening process to reduce the number of testing materials for the upscaled experiments. The evaluation process consisted of a three-cycle dehydration/hydration measurement at Tmax=100°C and Tmax=200°C. In case of the bromide samples a measurement of hydration conditions with Tmax=110°C and a water flow at e=18.68mbar, were added to the procedure to detect the maximum water uptake temperature. Also, a single dehydration to a temperature of Tmax=500°C was implemented to observe melting behavior and to easier calculate the samples’ stages of hydration from the remaining anhydrous mass. Materials which showed high energy storage density and improved cycle stability during this first evaluation were cleared for multi-cycle measurements of 10 to 25 dehydration and hydration cycles at Tmax = 100 to 120°C and the evaluations at m=20 to 100g scale. An estimate for the specific heat capacities at different temperatures of the materials which passed the initial stage was calculated from the TGA/DSC results as well. The laboratory scale measurement setup went through five stages of refining, which led to reducing the intended maximum sample mass from m=100g to m=20g. A switch from supplied liquid water to water vapor as the used reactant was also implemented in exchange for improved dehydration conditions. Introducing a vacuum pump for evaporating the water limited the influence of outside heat sources during hydration and in-situ dehydration was enabled as to not disturb the state the samples were settling in between measurements. Baseline calculation from blanc measurements with glass powder and attempts to calculate the specific heat capacity cp of the tested materials by 6 applying the Joule-Lenz-law to the measurement apparatus was another step of method development. The evaluation process of the laboratory scale tests at the final setting consisted of 1 to 5 cycle measurements of in-situ dehydration and hydrations with applied vacuum for t=30 minutes at p~30mbar. Upscaling the sample mass to m=20g allowed for a close observation of different material behaviors. Agglomeration, melting and dissolving of the m=10mg samples during the TGA/DSC analysis can be deducted from the recorded measurement curves and the state of the sample after measurement. However, at laboratory scale the visible volume changes, observed sample consistency after agglomeration and an automatic removal of molten and dissolved sample mass during the measurement allowed for a better characterization and understanding of the magnitude of the actual changes. This was done for the first time, particularly for mixed salts. Of the original number of 62 samples, 4 mixtures which passed the initial TGA/DSC screening namely {2MgCl2+ KCl}, {2MgCl2+CaCl2}, {5SrBr2+8CaCl2} and {2ZnCl2 + CaCl2} were chosen for further evaluation. The multi-cycle TGA/DSC measurements of {2MgCl2+ KCl}, {2MgCl2+CaCl2} and {5SrBr2+8CaCl2} showed an improved cycle stability for all three materials over the untreated educts. Of the four materials {2ZnCl2 + CaCl2} displayed the strongest deliquescence during hydration in the upscaled experimental setup. {2MgCl2+CaCl2} proved to be the most stable material regarding the heat storage density. The {MgCl2} content of the mixture is likely to partially or completely react to {Mg(OH)Cl} at temperatures of T>110°C, which however does not impede the heat storage density. {5SrBr2+8CaCl2} displayed a low melting point in hydrated state, causing a fast material loss. This makes it an undesirable storage material. A lower heating rate may still help to avoid an early melting. The {2MgCl2+KCl} mixture was the most temperature stable of the mixtures showing no melting or dissolving behavior. A reaction of the {MgCl2} component of the mixture to {Mg(OH)Cl} was not observed within the applied temperature range of T=25 to 200°C.
Climate change and atmospheric deposition of nitrogen affect biodiversity patterns and functions of forest ecosystems worldwide. Many studies have quantified tree growth responses to single global change drivers, but less is known about the interaction effects of these drivers at the plant and ecosystem level. In the present study, the authors conducted a full-factorial greenhouse experiment to analyse single and combined effects of nitrogen fertilization (N treatment) and drought (D treatment) on 16 morphological and chemical response variables of one-year-old Fagus sylvatica seedlings originating from eight different seed families from the Cantabrian Mountains (NW Spain). Drought exerted the strongest effect on response variables, reflected by decreasing biomass production. However, D and N treatments interacted for some of the response variables, indicating that N fertilization has the potential to strengthen the negative effects of drought (with both antagonistic and amplifying interactions). For example, combined effects of N and D treatments caused a sevenfold increase of necrotic leaf biomass. The authors hypothesize that increasing drought sensitivity was mainly attributable to a significant reduction of the root biomass in combined N and D treatments, limiting the plants' capability to satisfy their water demands. Significant seed family effects and interactions of seed family with N and D treatments across response variables suggest a high within-population genetic variability. In conclusion, the findings indicated a high drought sensitivity of Cantabrian beech populations, but also interaction effects of N and D on growth responses of beech seedlings.
Metals fulfill crucial functions in areas as diverse as renewable energy, digitization and life style appliances, mobility, communication, or medicine. In the context of sustainability, achieving a more sustainable metal use means (i) minimizing the adverse effects associated with metal production and use and (ii) sustaining the availability of metals in a way that benefits present and future generations. Urgent need to act to avoid bottlenecks as well as meeting the challenge of possible conflicts of use among those areas of application calls for appropriate strategy making to intervene in the complex field of metal production and use that involves various, often interlinked operating levels, actors, and spatial and temporal scales. This dissertation focuses on strategies as a means to intervene in a system. It pursues the question, which design features could guide future strategy making to foster sustainability along the whole metal life cycle, and especially, how a better understanding of temporalities, i.e. understanding time in a diverse sense, could improve strategy design and help to bridge the assumed "transformation-material gap". This research converges the results from four research studies. A conceptual part explores the role of temporalities for interventions in complex and interlinked systems, which adds to the conceptual basis, on which the empirical part builds up to explore present and future interventions in metal production and use. The research revealed three essential needs that future strategies must tackle: (i) managing the complex interlinkages of processes and activities on various operational levels and spatial and temporal scales, (ii) providing clear guidance concerning the operationalization of sustainability principles, and (iii) keeping activities within the planet’s carrying capacity and embracing constant change as an inherent system characteristic. In response to these needs, the author developed three guidelines with two design features each (one relating to content, and one to the process of formulating and implementing the strategy) to guide future strategy making. The results show that time matters in this respect. If considered in close relation to space and diversely understood in the sense of temporalities, it serves to (i) understand the impact (duration and magnitude) of an intervention, (ii) recognize patterns of change that go beyond establishing linear, one-dimensional connections, and (iii) design interventions in a way that considers the resilience of a system. These findings can contribute to closer considering our understanding of transformation processes towards sustainability in future interventions in metal production and use.
Global climate change and environmental degradation are largely caused by human activity, thus progress towards a sustainable future will require large-scale changes to human behavior. Human-nature connectedness (HNC) - a measure of cognitive, emotional, spiritual and biophysical linkages to natural places - has been identified as a positive predictor of sustainability attitudes and behaviors. While calls to "reconnect to nature" in order to foster sustainability outcomes have become common across science, policy and practice, there remains a great deal of uncertainty, speculation, and conceptual vagueness around how this ought to be implemented. The overarching aim of this thesis is to advance conceptual and empirical understandings of HNC as a leverage point for pro-environmental outcomes and sustainability transformation. In particular, the thesis attempts to assess the nuances of the HNC-PEB (pro-environmental behavior) relationship by investigating the scalar relationships between where someone feels connected to nature and where someone acts pro-environmentally. This research was conducted through conceptual exploration, systematic literature reviews using hierarchical cluster analysis, and empirical case studies relying on structural equation modeling and two-step cluster analysis. The relationship between HNC and pro-environmental attitudes and behaviors was investigated in a small microregion of Transylvania, Romania, where traditional relationships with the land and changing socio-economic characteristics provided an interesting case study in which to explore these connections. The key findings can be organized into three sections: Section A, which addresses HNC and its potential for sustainability transformation; Section B, which addresses HNC as a determinant of PEB outcomes, and Section C, which explores the relationships between human-nature connectedness and energy conservation norms, attitudes, and behaviors. Results cumulatively suggest that HNC is a multidimensional construct that requires greater integration across heterogeneous disciplinary and methodological boundaries in order to reach its potential for meaningful sustainability transformation. Results also highlight the critical need to adopt systemic approaches to understanding how interactions between human-nature connections, norms, attitudes, and behaviors are hindering or promoting sustainability outcomes.