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Item type:Publication, Access status: with files , Life cycle assessment of electricity production from airborne wind energy(2015-08); Global energy supply is closely linked with some of the greatest challenges of our society. A rising demand has to be met whereas conventional energy sources are depleting and emit considerable amounts of greenhouse gases. Renewable energy technologies are increasingly promoted to face these issues, especially in the electricity industry. Research has shown, that renewables are superior to conventional energy technologies in many environmental aspects but are not free of burdens. However, the main causes of impacts are shifted to other life cycle phases than operation. The emerging of airborne wind energy (AWE), as a new stakeholder within the renewables, presents an ecologically promising option since it accesses wind resources of outstanding quality with little material consumption. As of now, there is no environmental assessment of this new technology available. The goals of this study are (1) the determination of environmental burden of electricity generation with AWE on the categories global warming and consumption of energy resources, (2) the identification of main contributors to these categories, (3) the determination of the energy payback time and (4) an assessment whether use of this technology would lower impact of electricity supply in the mentioned categories. An AWE design is chosen for the investigations, which appears possible to become a dominating design. Even though uncertainties arise from the analysis of a specific design, the outcomes of the study could serve as a first reference for system developers and for decision-makers to evaluate support or engagement in this technology. To this end, a life cycle assessment (LCA) was executed, which allows tracking of category indicators from cradle to grave. Specific AWE facilities of 1.8 MW were defined and analyzed in a 300 MW plant under low wind conditions. The modeling follows an estimated dominating design or conservative choices. The results are expected to be on the upper range. The results of the model are presented and discussed and checked for robustness in a sensitivity study. A comparison to a similar conventional wind power plant and the electricity grid mix allows a better classification of the results. The category indicator result in global warming potential (GWP) is 5.611 gCO2-eq./kWh. 65 % of that occur in the phase raw material and manufacturing, 3 % during installation, 28 % during operation and 4 % in disposal. The cumulated energy demand (CED) is 75.2 kJ-eq./kWh. The invested energy during the entire life cycle is 2.1 % of the total generated electricity and is recovered after 5 months or 153 days of operation. This corresponds with an energy yield ratio of 48%. The tether accounts for 5.5 and 8.1 % in GWP and CED, including its replacements. Lower lifetimes have significant influence, higher are with marginal effect. The environmental effects from the wing manufacture arise by 75% from the carbon fiber reinforced polymer but are only 2.6 and 5.6 % in GWP and CED. The biggest contribution is from generator and gearbox, which account for 35 and 30 % in GWP and CED respectively, including replacement of all gearboxes. In total, 30 % of the impacts come from balance of station components and 70 % from the AWE facility. The latter is the percentage that the system developer can influence directly. Compared to a conventional wind plant that was modeled in a similar way, the AWE plant consumed 23 % of the mass, causes 49 % of the GWP and consumes 55 % of the CED. Energy payback time was 2 times lower. Compared to German electricity mix the plant causes 0.87 % of the GWP and has 0.74 % of the CED. Even with a conservative approach the study confirms the expectation of low impact in the considered categories and presents first numerical results.Publicationtype: Master Thesis1651 2897 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Effekte von Titandioxidnanopartikeln auf den Nematoden Caenorhabditis elegans unter besonderer Berücksichtigung von UV-Strahlung(2013); Engineered nanoparticles (ENPs) are increasingly used in a variety of industrial and consumer products and will inevitably enter the aquatic environment. Modelling environmental emissions of nanoscale titanium dioxide (nTiO2) resulted in predicted sediments accumulation rates up to 1.4 mg/kg*year. Potential effects of ENPs on human health and the environment are still poorly understood. In comparison to their bulk scale counterparts, nanoparticles pose a higher risk to the environment for several reasons. First, their small size (< 100 nm) enables them to penetrate organisms and cells, where they can interfere with cellular processes. Also, due to their large surface area, nanoparticles have the potential to affect bioavailability and toxicity of co-existing contaminants like heavy metals or PAHs by acting as a carrier. For TiO2-particles, photocatalytic activity increases with increasing surface area, as this property depends strongly on the accessibility of the particles’ surface to the environment. In order to assess the nanoscale specific effects and the potential impacts of varying environmental conditions, this study addresses the following questions: 1) Does particle size affect the toxicity of TiO2 particles? 2) How does sunlight impact the toxicity of photocatalytically active nanoparticles? 3) Does nTiO2 interact with phenanthren as a common co-contaminant in sediments? 4) How does nTiO2 impact phenanthren as co-contaminant exposed to sunlight? The nematode Caenorhabditis elegans was used to determine the chronic toxicity of two different TiO2-materials: A 21 nm, nanoscale TiO2 (P25) and a 90 to 230 nm, bulkscale TiO2 (bTiO2: NM100). While agglomerating to a comparable secondary particle size of 300 to 1500 nm, only nTiO2 inhibited reproduction of C. elegans significantly with a LOEC of 10 mg/l and an EC50 > 100 mg/l, while no effects were observed for bTiO2. Results of Microscopy and ‘Energy Dispersive X-Ray-analysis’ indicate that both materials are taken up by the intestinal tract of C. elegans. Further examination of the agglomeration of TiO2-particles in the gut of C. elegans showed that both materials caused a dysfunction of the defecation process by inhibiting feeding efficiency. Exposition to simulated solar radiation increased toxicity of nTiO2 to an EC50 of 53 mg/l, while no phototoxicity has been observed for bTiO2. Since nTiO2 produces more reactive oxygen species (ROS) than bTiO2, when measured as photo-degradation of methylene blue, the observed photoactivated effects of nTiO2 are likely due to oxidative stress. To test for a corresponding genetic response, expression of sod-3 was analyzed on mRNA and enzymatic level by using real-time PCR and a sod-3:gfp transgenic strain, respectively. Independent of the applied light conditions, nTiO2 did not impact sod-3 expression, suggesting that no ROS-production occurred within C. elegans cells. Therefore it was concluded that the nano-particles did not enter the cells and the observed phototoxicity was evoked by oxidative damage at the outer apical membrane of the intestinal cells, due to modes of action such as lipid and protein peroxidation. nTiO2 was not found to have a significant effect on the toxicity or bioavailability of phenanthrene, when measured as gene expression of cyp-35C1. In combined exposure with radiation, nTiO2 appears to block the impact of UV-light on the photo-sensitive PAH and decreases photo-toxicity. The results of this study highlight the importance of primary particle size and environmental parameters on the toxicity of TiO2 materials. Even though bTiO2 and nTiO2 agglomerate to the same secondary particle size in the test system, only nano-TiO2 is toxic to C. elegans. Missing evidence for cell internal effects of the photocatalytically active nTiO2 suggests that nanoparticles act extracellular by inducing oxidative damage of the epithelial membranes in the gut. Potential enhancement of nano-TiO2 toxicity by physico-chemical parameters stresses the necessity of further investigations into their ecotoxicological effects under different environmental conditions.Publicationtype: Doctoral Thesis740 2913 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Development of ecologically relevant quality indicators for sediment microbial communities(2009); An integrated quality indicator (IQI) was developed taking ecotoxicities and nutrient cycling as key parameters to address the ecological relevance of sediment microbial communities. The parameters were integrated using weight of evidence approach and a fuzzy rule-based model. As an example of application, the aging of contaminants was evaluated. The IQI provides a framework to supplement currently chemical dominant sediment quality guidelines in reaching the good ecological quality status requested by the European Water Framework Directive.Publicationtype: Doctoral Thesis414 1387 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Die Bedeutung partikel-assoziierten Cadmiums für die Bioverfügbarkeit und Bioakkumulation im Nematoden Caenorhabditis elegans(2009); To investigate the impact of multiple cadmium exposure pathways on internal availability and accumulation, C. elegans were exposed to different particles and to dissolved cadmium. Internal cadmium availability was determined using the transcript level of cdr-1 gene, as quantified by real-time PCR. Particle-associated cadmium exposure was the predominant contributor to cadmium bioavailability and bioaccumulation.Publicationtype: Doctoral Thesis957 1026 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Zur Bedeutung der Schadstoffexposition auf die Genexpression und Reproduktion von Caenorhabditis elegans(2008); Effects of fluoranthene-exposition via water phase and via dietary particles (Escherichia coli) on gene expression and number of offspring were investigated in the nematode Caenorhabditis elegans. Exposition via particles increased the concentration at the target site, resulting in adverse effects on the whole organism. The combination of gene expression and life cycle test is a useful tool to reveal elictors of toxicity.Publicationtype: Doctoral Thesis855 1238