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Solar power appears to be one of the most promising resources to meet the medium and long term renewable energy targets. The integration of large amounts of photovoltaic (PV) generation into distribution networks faces some limitations due to the network constraints. The PV community became well aware of these limitations in the last years. While first solutions have been pointed out mainly for large installations connected to the medium voltage network, the specificities of low voltage networks are still not fully understood. This paper aims at explaining the challenges associated to the planning and operation of low voltage network with high PV penetration. The actual impact of PV infeed is quantified on the basis of real and accurate network, load and generation data. Results from unsymmetrical load-flow computations are presented and the implementation of reactive power-based voltage control is shortly discussed. 26th European Photovoltaic Solar Energy Conference and Exhibition; 4469-4478

Climate change increases the frequency and intensity of certain kinds of natural hazard events in alpine areas. This interdisciplinary study addresses the hypothetical possibility of relocating the residents of three alpine areas in Austria: the Sölk valleys, the Johnsbach valley, and the St. Lorenzen/Schwarzenbach valleys. Our particular focus is on these residents’ expectations about such relocations. We find that (1) many residents expect that in the next decades the state will provide them with a level of natural hazards protection, aid, and relief that allows them to continue to live in these valleys; (2) this expectation receives some legal protection but only when it is associated with fundamental rights; and (3) the expectation is morally significant, i.e., it ought to be considered in assessing the moral rightness or justness of relocation policies. These results suggest legal changes and likely extend to many other (Austrian) alpine areas as well. Fonds zur Förderung der Wissenschaftlichen Forschung W 1256-G15 Version of record

Photovoltaic (PV) technology allows large-scale investments in a renewable power-generating system at a competitive levelized cost of electricity (LCOE) and with a low environmental impact. Large-scale PV installations operate in a highly competitive market environment where even small performance losses have a high impact on profit margins. Therefore, operation at maximum performance is the key for long-term profitability. This can be achieved by advanced performance monitoring and instant or gradual failure detection methodologies. We present in this paper a combined approach on model-based fault detection by means of physical and statistical models and failure diagnosis based on physics of failure. Both approaches contribute to optimized PV plant operation and maintenance based on typically available supervisory control and data acquisition (SCADA) data. The failure detection and diagnosis capabilities were demonstrated in a case study based on six years of SCADA data from a PV plant in Slovenia. In this case study, underperforming values of the inverters of the PV plant were reliably detected and possible root causes were identified. Our work has led us to conclude that the combined approach can contribute to an efficient and long-term operation of photovoltaic power plants with a maximum energy yield and can be applied to the monitoring of photovoltaic plants.

Meteorological forcing at the air-water interface is the main determinant of the heat balance of most lakes (Edinger et al., 1968; Sweers, 1976). Year-to-year changes in the weather therefore have a major effect on the thermal characteristics of lakes. However, lakes that differ with respect to their morphometry respond differently to these changes (Gorham, 1964), with deeper lakes integrating the effects of meteorological forcing over longer periods of time. Other important factors that can influence the thermal characteristics of lakes include hydraulic residence time, optical properties and landscape setting (e.g. Salonen et al., 1984; Fee et al., 1996; Livingstone et al., 1999). These factors modify the thermal responses of the lake to meteorological forcing (cf. Magnuson et al., 2004; Blenckner, 2005) and regulate the patterns of spatial coherence (Chapter 17) observed in the different regions (Livingstone, 1993; George et al., 2000; Livingstone and Dokulil, 2001; Jarvinen et al., 2002; Blenckner et al., 2004)

Adsorption refrigeration, as a renewable cooling method, has received more attention in the last few years. The interest in this technology comes especially from developing and tropical countries, where the demand for cooling increases every year due to economy and population growth. Based on this scenario, this work aims to develop a numerical model of an adsorption chiller driven with solar energy, which can be used to optimize the cooling system operation of the building where the device is situated and compare it with the current cooling methods in use. The numerical study here presented was created using Matlab/Simulink™, it is based on a lumped parameter model that relies on physical properties and represents a cooling system using a pair of silica gel-water in a two-bed chiller. In this study, the authors proposed a simplified version of the system and the numerical model, which aims to reduce the simulation time and provide faster results. Besides the temperatures in the system, which range from 52 °C to 72 °C in the hot cycle and 12 °C to 23 °C in the chilled water cycle, the results also include the variation of water uptake in the two adsorbent beds. In general, the simulated temperature, cooling and heating power and coefficient of performance (COP) are in fair agreement with the literature data, nevertheless, the final results show that improvements still have to be performed.

This paper is devoted to study the electrochemical behavior of Pt catalyst in a polymer electrolyte fuel cell at various operating conditions and at different electric potential difference (also known as voltage) cycling applied in accelerated stress tests. The degradation of platinum is considered with respect to the Pt ion dissolution and the Pt oxide coverage of catalyst described by a one-dimensional model. In the model, degradation rate increases with temperature and decreasing particle diameter of Pt nano-particles. The theoretical study of the underlying diffusion system with the nonlinear reactions is presented by analytical methods and gives explicit solutions through a first integral of the ODE system. Numerical tests are obtained using a second order implicit-explicit scheme. The computer simulation shows that the lifetime of the catalyst depends on the voltage profile and the upper potential level. By this Pt mass loss is more significant at the membrane surface than at the gas diffusion layer.

Ziel der Diplomarbeit ist es, sich kritisch mit dem Thema Sanierung im Bestand und der Revitalisierung der Plattenbausiedlungen in den neuen Europ��ischen L��ndern, auseinanderzusetzen. Dies ist wichtig, weil das Sanierungsproblem nicht nur im Mittelosteurop��ischen Raum (MOE) gegenw��rtig ist, sondern auch in vielen westeurop��ischen Industriel��ndern ein zentrales Thema geworden ist. Im Zuge der Ausarbeitung wird in Bezug auf Deutschland ein geschichtlicher R��ckblick gemacht warum diese Siedlungen entstanden, wie viele Plattenbauten im MOE Raum zu finden sind und welche Geb��udetypologien in Deutschland am meisten zur Anwendung kamen. Diese Arbeit gibt einen ��berblick ��ber den Stand der Wissenschaft, welche Sanierungskonzepte bereits existieren, inwieweit sie praktisch umgesetzt sind und welche Verbesserungsm��glichkeiten bestehen. Untersucht wird, ob es neue innovativere L��sungsans��tze f��r die Sanierung im Bestand gibt und wie diese bereits umgesetzt sind oder aussehen k��nnten. Untersucht wird hierzu ein g��ngiger Geb��udetypus aus Deutschland - jener, der am h��ufigsten zur Anwendung kam. Es handelt sich hier um ein reines Gedankenexperiment wie man mit innovativen Systemen schaffen k��nnte, den Energieverbrauch wesentlich zu reduzieren. Bedenkt man die Gesamtfl��che der noch zu sanierenden Geb��ude, findet man auch aus marktpolitischer Sicht ein enormes Entwicklungspotential, da die Erhaltung der Bausubstanz notwendig ist und ein Abriss unm��glich. Es soll mit dieser Diplomarbeit gezeigt werden, dass es sinnvoll ist sich auch an der Fakult��t f��r Architektur mit der Forschung zu besch��ftigen, um neue und sinnvolle Methoden zur Geb��udesanierung zu entwickeln. Es wird bereits an der TU Wien mit dem Modul Experimenteller Hochbau ein Schritt in diese Richtung erm��glicht, den es gilt weiter auszubauen! Aim of the thesis is to deal critically with the issue of renovation and revitalization of prefabricated housing estates in the new European countries. This is important because this issue is present not only in the Middle East European Space (MEO), but also has become a key issue in many Western European industrial countries. Initially a historical review is made referring to Germany why these settlements have been built, how many panel buildings can be found in the CEE region and the building typologies which are the most applied in Germany. This work gives an overview of the state of scientific knowledge, which remedial concepts already exist, how they are implemented in practice and what are the opportunities for improvement. It will be investigated whether there are new innovative solutions for the renovation of existing panel buildings and how these have already been implemented or how they could look like. A common type of building in Germany - the one which most often was used - is examined as an example. We are discussing a pure thought experiment how one might manage to reduce the energy consumption significantly with the help of innovative systems. Considering the total area of the yet to be rehabilitated buildings this is quite a market perspective and an enormous development potential, the preservation of the panel buildings is the better alternative to demolition. It will be shown in this thesis that it is useful even at the Faculty of Architecture to do some research for finding new and useful methods to develop building renovation. The combination of the classic art of construction with experimental science, is able to create new technologies, appliances and additives which is already done in the module Experimental construction at the Vienna University of Technology.