A behavioral macroeconomic model with endogenous boom-bust cycles and leverage dynamcis

We merge a financial market model with leverage-constrained, heterogeneous agents with a reduced-form version of the New-Keynesian standard model. Agents in both submodels are assumed to be boundedly rational. The fi nancial market model produces endogenously arising boom-bust cycles. It is also capable to generate highly non-linear deleveraging processes, fi re sales and ultimately a default scenario. Asset price booms are triggered via self-fulfilling prophecies. Asset price busts are induced by agents' choice of an increasingly fragile balance sheet structure during good times. Their vulnerability is inevitably revealed by small, randomly occurring shocks. Our transmission channel of financial market activity to the real sector embraces a recent strand of literature shedding light on the link between the active balance sheet management of financial market participants, the induced procyclical fluctuations of desired risk compensations and their final impact on the real economy. We show that a systematic central bank reaction on financial market developments dampens macroeconomic volatility considerably. Furthermore, restricting leverage in a countercyclical fashion limits the magnitude of financial cycles and hence their impact on the real economy. --behavioral economics,New-Keynesian macroeconomics,monetary policy,agent-based financial market model,leverage,macroprudential regulation,financial stability,asset price bubbles,systemic risk

Impact of the oxy-fuel combustion on the corrosion behavior of advanced austenitic superheater materials

AbstractAlthough the road-map of the oxy-fuel process seems to be very advanced, there are still plenty of open questions. One of the significant ones is the corrosive behaviour of the heat exchanger surfaces. The Institute of Combustion and Power Plant Technology, University of Stuttgart, performs research on the fireside corrosion under oxy-fuel and conventional combustion conditions for the current and supercritical power plants considering the influence of combustion modus, gas atmosphere and fly ash deposits on the waterwall and superheater surfaces. Since the oxy-fuel-combustion atmosphere is composed of recirculated flue gases and pure oxygen, significantly higher concentrations of CO2, SO2 and H2O are present compared to the conventional combustion of coal with air as an oxidizer. In the here presented study the influence of an oxy-fuel combustion of a hard-coal on the surface of selected superheater materials is discussed and compared to the results obtained for lignite. Especially the interactions between the flue gas atmosphere, ash deposits and heat exchanger materials are studied in detail. The investigation encompassed in this paper has been focused on impacts of oxide-scale growth, carbon enrichment of the materials and sulphur-induced corrosion.Increased sulphur-induced corrosion has been observed in samples exposed to the oxy-combustion atmosphere. The noticed higher depth of corrosive attack of the oxy-fuel samples might be explained by a higher partial pressure of SO2 which is characteristic for oxy-fuel process. Moreover in certain cases the sulphur might be released by the deposits. Beside that, the oxy-fuel samples were exposed to much higher partial pressures of carbon dioxide comparing to the air-case leading apparently to rapid and massive internal carbon enrichment in the oxide scale. Moreover dependence between the chromium content and oxidation ability of the austenitic materials surfaces was noticed under oxy-fuel conditions

Monetary policy and systemic risk on financial markets : concepts, transmission channels and policy implications

The present thesis explores the issue of systemic risk on financial markets and its interplay with monetary policy. Systemic risk is defined as the risk of experiencing a severe financial crisis. It is inefficiently high in the absence of appropriate regulation due to the presence of systemic externalities, which arise if financial institutions do not internalize the consequences of their actions for systemic stability. More specifically, such behavior may lead to vulnerable financial networks, poor diversification, fire sales, inefficient distribution of liquidity as well as to breakdowns of markets characterized by incomplete information. Macroprudential regulation aiming at systemic stability should therefore focus on the mitigation of systemic externalities. However, a critical assessment of the current state of financial regulation reveals that several important drivers of systemic risk remain unaddressed. Insufficient containment of systemic risk poses a challenge for monetary policy. First, financial crises have adverse effects on macroeconomic stability. Second, monetary policy itself has the potential to affect the evolution of systemic risk. It is subsequently tried to shed light on potential transmission channels running from an expansive policy stance to an increase in systemic risk. On a theoretical basis, it is found that a monetary expansion tends to induce higher leverage as well as credit risk and less stable refinancing in the intermediation sector. An empirical analysis of the US economy based on vector autoregressions supports this risk-taking channel. Moreover, the analysis of a simple macro-financial model shows that procyclical risk-taking behavior of financial intermediaries produces additional macroeconomic volatility. Optimal policy consists of a combination of strict capital requirements and an interest rate rule featuring an explicit reaction to credit dynamics. In a final step, I discuss implications for monetary policy. If macroprudential regulation is not strict enough, it is advisable to embark on a strategy of preemptive interest rate hikes in an environment of rising systemic risk. Its implementation could be achieved by a slight modification of the existing two-pillar strategy of the European Central Bank. Alternatively, central banks could rely on output gap measures which take financial conditions into account. However, such a strategy can increase short-term macroeconomic volatility. Hence, monetary policy faces the additional trade-off of balancing medium-term financial stability against macroeconomic stability in the short run. Moreover, monetary policy and macroprudential regulation should be carefully coordinated to deliver welfare-maximizing outcomes.Die vorliegende Arbeit beleuchtet das Phänomen von systemischem Risiko auf Finanzmärkten sowie dessen Zusammenhänge mit der Geldpolitik. Systemisches Risiko wird als das Risiko des Eintritts einer schweren Finanzkrise definiert. Bei ausbleibender Regulierung ist das systemische Risiko ineffizient hoch. Dies ist auf systemische Externalitäten zurück zu führen. Diese treten auf, wenn Finanzmarktteilnehmer die Konsequenzen ihrer individuellen Entscheidungen für die Systemstabilität nicht berücksichtigen. Dieses Verhalten führt unter Umständen zur Ausbildung fragiler Forderungsnetzwerke, zu ungenügender Diversifikation, zu ungeordneten Notverkäufen von Wertpapieren, zu einer ineffizienten Verteilung von Liquidtät sowie zum Zusammenbruch von Märkten welche durch asymmetrische Information gekennzeichnet sind. Eine auf Systemstabilität bedachte makroprudenzielle Regulierung sollte daher die Korrektur dieser Externalitäten anstreben. Eine kritische Betrachtung des aktuellen Regulierungsrahmens zeigt jedoch, dass mehrere wichtige Treiber von systemischem Risiko nach wie vor nicht adäquat adressiert werden. Eine ungenügende Begrenzung des systemischen Risikos stellt für die Geldpolitik eine Herausforderung dar. Zum einen gefährden Finanzkrisen die makroökonomische Stabilität, zum anderen wird das systemische Risiko möglicherweise durch die Geldpolitik beeinflusst. Folgend wird versucht, mögliche Transmissionskanäle von einem expansiven geldpolitischen Kurs hin zu erhöhtem systemischem Risiko darzustellen. Auf modelltheoretischer Ebene wird gezeigt, dass expansive Geldpolitik tendenziell zu erhöhter Verschuldung, einer Zunahme des Kreditrisikos sowie zu einer fragileren Refinanzierung im Intermediationssektor führt. Eine empirische Untersuchung für die amerikanische Volkswirtschaft auf Basis einer Vektorautoregressionsanalyse liefert deutliche Anzeichen für das Vorliegen eines derartigen Risikoneigungskanals. Zudem zeigt die Analyse eines simplen Macro-Finance Modells, dass das prozyklische Risikoverhalten von Finanzintermediären zusätzliche makroökonomische Schwankungen produziert. Die optimale Politikreaktion besteht aus rigiden Eigenkapitalvorschriften sowie einer geldpolitischen Zinsregel mit einer expliziten Reaktion auf Kreditdynamiken. Zuletzt werden geldpolitische Implikationen diskutiert. Falls die makroprudenzielle Regulierung nicht rigide genug ist, sollte die Geldpolitik in einem Umfeld von ansteigendem systemischem Risiko präventiv die Zinsen erhöhen. Die Implementierung dieser Strategie könnte mithilfe einer geringfügigen Modifikation der bestehenden Zwei-Säulen Strategie der Europäischen Zentralbank erfolgen. Alternativ könnten Zentralbanken Messgrößen für die Outputlücke verwenden, welche den Zustand des Finanzmarkts berücksichtigen. Jedoch kann solch eine Strategie die kurzfristige Makrovolatilität erhöhen. Daher ergibt sich für die Geldpolitik ein zusätzlicher Zielkonflikt zwischen mittelfristiger Finanzstabilität und der makroökonomischen Stabilität in der kurzen Frist. Zudem sollten Geldpolitik und makroprudenzielle Regulierung sorgfältig koordiniert werden, um wohlfahrtsoptimale Ergebnisse zu erzielen

Cold Model Investigations of a High Temperature Looping Process in a Dual Circulating Fluidized Bed System

The Calcium Looping process is a promising post-combustion CO2 capture technology. A 200 kWth Dual Circulating Fluidized Bed has been built at IFK, University of Stuttgart. Tests were carried out on a hydrodynamically scaled cold model. Operating parameters have been varied, while the suitability of the 200 kWth design has been prove

The oxycoal process with cryogenic oxygen supply

Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly ash or the deposits that form. In particular, detailed nitrogen and sulphur chemistry was investigated by combustion tests in a laboratory-scale facility. Oxidant staging, in order to reduce NO formation, turned out to work with similar effectiveness as for conventional air combustion. With regard to sulphur, a considerable increase in the SO2 concentration was found, as expected. However, the H2S concentration in the combustion atmosphere increased as well. Further results were achieved with a pilot-scale test facility, where acid dew points were measured and deposition probes were exposed to the combustion environment. Besides CO2 and water vapour, the flue gas contains impurities like sulphur species, nitrogen oxides, argon, nitrogen, and oxygen. The CO2 liquefaction is strongly affected by these impurities in terms of the auxiliary power requirement and the CO2 capture rate. Furthermore, the impurity of the liquefied CO2 is affected as well. Since the requirements on the liquid CO2 with regard to geological storage or enhanced oil recovery are currently undefined, the effects of possible flue gas treatment and the design of the liquefaction plant are studied over a wide range

Stoffbilanzmodellierung für Spurenstoffe auf Einzugsgebietsebene

Stand: 28. Juli 202036

Occurrence and levels of micropollutants across environmental and engineered compartments in Austria

Occurrence and concentration of a broad spectrum of micropollutants are investigated in Austrian river catchments, namely polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), organotin compounds, perfluoroalkyl acids (PFAAs) and metals. The parallel analysis across multiple environmental and engineered compartments sheds light on the ratio of dissolved and particulate transport and on differences in concentration levels between point and diffuse emission pathways. It is found that some PAHs and organotins are present in rivers, groundwater and bulk deposition at higher concentrations than in municipal wastewater effluents. Among PFAAs and metals, highest concentrations were recorded either in atmospheric deposition or in discharges from wastewater treatment plants. The relevance of the analysis across compartments is best shown by the case of perfluorooctanesulfonic acid (PFOS). Despite municipal wastewater effluents being the emission pathway with highest concentrations, this study reveals that not only rivers, but also atmospheric deposition and groundwater sometimes exceed the environmental quality standard for surface waters. Moreover, this work reveals partially counterintuitive patterns. In rivers with treated wastewater discharges, increasing levels of dissolved compounds were measured at rising flow conditions, whereas the opposite would be expected owing to the dilution effect. This might derive from the mobilisation from soil or suspended particulate matter or rather find its explanation in high concentrations in atmospheric deposition. These hypotheses require however being tested through targeted studies. Additional future research includes the analysis of how regional or catchment specific characteristics might alter the relative importance of different emission pathways, and the modelling of emission and river loads to assess their relative contribution to river pollution.Federal Ministry of Sustainability and Tourism (BMNT)6366531

NOx control in coal combustion by combining biomass co-firing, oxygen enrichment and SNCR

There has been renewed interest in evaluating NOx emission control by selective non-catalytic reduction (SNCR) combined with biomass co-firing to meet impending enforcement of NOx emission limits for power generation plant. Oxygen enrichment for the concentration of CO 2 in the flue gas has been observed in this work to have benefits for NOx emission control. This paper presents new information on the effect of combining biomass co-firing with SNCR under various oxygen enriched and air-staging conditions performed in the 20 kW combustion facility. Biomass has a higher tendency to generate CO and produced better reductions in NO x emission with and without using SNCR. NO reduction of around 80% were attained using SNCR for 15% and 50% blending ratios of biomasses at 21% overall O2 concentration for unstaged combustion. Whereas, a range of 40-80% NO reductions were attained for coal (Russian Coal) and 15% co-fired biomasses with 3.1-5.5% overall O2 concentration at 22-31% levels of flame staging. Moreover, it was found that better NOx removal efficiency was attained for higher NOx emission baselines under both oxygen enriched and normal firing conditions. However, SNCR NOx control for both coal or coal-biomass blends was observed to produce higher NOx reductions during O2 enrichment, believed to be due to the self-sustained NOx reduction reactions. Hence, NOx control by SNCR, oxygen enriched co-firing in power station boilers would result in lower NOx emissions and higher CO2 concentration for efficient scrubbing with better carbon burnouts. © 2012 Elsevier Ltd. All rights reserved