Frequency and duration of low-wind-power events in Germany

In the transition to a renewable energy system, the occurrence of low-wind-power events receives increasing attention. We analyze the frequency and duration of such events for onshore wind power in Germany, based on 40 years of reanalysis data and open software. We find that low-wind-power events are less frequent in winter than in summer, but the maximum duration is distributed more evenly between months. While short events are frequent, very long events are much rarer. Every year, a period of around five consecutive days with an average wind capacity factor below 10% occurs, and every ten years a respective period of nearly eight days. These durations decrease if only winter months are considered. The longest event in the data lasts nearly ten days. We conclude that public concerns about low-wind-power events in winter may be overrated, but recommend that modeling studies consider multiple weather years to properly account for such events.Comment: This is an update version after peer revie

Опыт создания баровых землерезных машин на базе траншейных экскаваторов

Lean premixed flames applied in modern gas turbines leads to reduce NOx emissions, but at the same time they are more susceptible to combustion instabilities than diffusion flames. These oscillations cause pressure fluctuations with high amplitudes and unacceptable noise as well as the risk of component or even engine failure. They can lead to pockets of fuel being formed in the mixing chamber and to bad mixing, which leads to increase in emissions. This paper reports the successful decoupling of the pressure and heat release inside the combustion chamber of a matrix burner using two actuation techniques. This led to the successful attenuation of the dominant instability modes occurring inside the combustor of the matrix burner. In the first case, acoustic forcing was used to decouple the pressure and the heat release inside the combustor. This was achieved by using a loudspeaker to modulate the primary air mass flow. This was followed by using acoustic forcing in CFD to decouple the pressure and heat release inside the combustor. For the action of the loudspeaker, sinusoidal forcing was used to mimic the modulation action of the diaphragm of the loudspeaker. In the second case, a fast gaseous “on-off” injector was used to modulate the primary fuel mass flow. After this, pilot fuel modulation was used to stabilize the flame. The control law governing the primary and pilot fuel modulation is discussed in details. The effect of open loop control on NOx emissions in the burner is also reported and discussed.</jats:p

Distributional Impacts of Carbon Pricing: A Meta-Analysis

Understanding the distributional impacts of market-based climate policies is crucial to design economically efficient climate change mitigation policies that are socially acceptable and avoid adverse impacts on the poor. Empirical studies that examine the distributional impacts of carbon pricing and fossil fuel subsidy reforms in different countries arrive at ambiguous results. To systematically determine the sources of variation between these outcomes, we apply an ordered probit meta-analysis framework. Based on a comprehensive, systematic and transparent screening of the literature, our sample comprises 53 empirical studies containing 183 effects in 39 countries. Results indicate a significantly increased likelihood of progressive distributional outcomes for studies on lower income countries and transport sector policies. The same applies to study designs that consider indirect effects, demand-side adjustments of consumers or lifetime income proxies

Die politische Ökonomie von Energietransitionen

Mitigating climate change is among the largest challenges for humanity in the 21st century. With the Paris Agreement, an overwhelming majority of states pledged to limit the global temperature increase to well below 2°C, and ideally, 1.5°C above pre-industrial levels. Many countries have translated these pledges into the goal of reducing emissions to net-zero, while global efforts to curb emissions increased gradually. However, with current climate policies in place, temperature levels will exceed the aspired targets. Implementing climate policies that reduce emissions and trigger low-carbon innovation is urgent, which requires understanding which climate policy instruments and their design options effectively reduce carbon emissions. Yet, whether the implementation of effective climate policies is politically feasible hinges on political economy factors. Understanding the political economy of energy transitions is thus crucial for successful climate policy making. This dissertation explores the interplay between design options of effective climate policy instruments and the political economy affecting their implementation. The four central chapters of this dissertation analyze the impact of market-based climate policies on low-carbon investments, how political economy factors affect coal deployment in multiple emerging economies including India, and narratives in the emerging discourse around hydrogen. The chapters provide the following key insights: First, a sufficiently high price floor in emissions trading systems would lead to higher low-carbon investment of especially green companies, while fossil investment of energy-intensive companies would be abolished. Second, the continued deployment of coal-fired power plants is shaped by political actors that try to meet the goals of economic growth, energy system stability, and low energy prices, but policymakers are also subject to the influence of the power sector. Third, ensuring a sufficient supply and the long-term availability of electricity motivates private and public coal investments in India, while regional coal jobs and established local vested interests pose major barriers for a prospective coal-phase out. Fourth, actors in the emerging hydrogen discourse share the goal of establishing a hydrogen economy, but conflicts emerge around the sectors in which hydrogen shall be used, around the envisaged production methods, and the desirability of imports. The findings entail the following implications for ongoing academic and political discussions: Ex-ante evidence provided by German energy managers suggest that price floors at sufficiently high levels would be important extensions of emissions trading systems. The findings complement previous ex-post studies on the effectiveness of the European Union Emissions Trading System that, until recently, were constrained by data from periods with low certificate prices, preventing predictions about possible impacts of higher prices. An expert survey about political economy factors in major coal countries highlights that there are political economy patterns that consistently occur across countries and thus, require special consideration in discussions about global coal phase-out policies. These findings also add to scant insights on the political economy in emerging economies. Detailed insights from expert interviews on Indian energy politics suggest that regional phase-out plans ensuring a just transition and restructuring the power system are both important measures to initiate a coal phase-out. Finally, the analysis of the emerging public discourse on hydrogen using German newspaper rticles provides first empirical insights of narratives used by different actors, and lays the ground for an enhanced understanding of current and potential upcoming controversies. A simple conceptual framework thereby contributes to theorizing sustainability transitions that span across multiple sectors. Overall, this dissertation combines insights on the design of climate policy instruments with the political economy around coal and hydrogen across different geographical contexts. Two chapters on Germany assess how design options for carbon pricing policies may affect low-carbon investments of firms, while analyzing the discourse around hydrogen emphasizes how narratives may influence the public perception around a low-carbon energy carrier. The findings underline the stark role of politics in setting economic incentives for low-carbon investment decisions, but also that the implementation of energy policies may be strongly debated and contested. Another two chapters focus on coal politics in several emerging economies and especially India, and highlight the complex challenges for domestic policymakers in these countries that aspire to foster coal phase-outs. Both chapters outline the trade-off arising between environmental goals and short term economic growth but also point to the role of vested interests and lobbying. All chapters jointly show that understanding both politics and policy instruments in conjunction are of utmost importance for successfully mitigating climate change.Die Verminderung des Klimawandels ist eine der größten Herausforderungen der Menschheit im 21. Jahrhundert. Mit dem Übereinkommen von Paris (Paris Agreement) hat sich eine überwältigende Mehrheit der Staaten dazu verpflichtet den globalen Temperaturanstieg auf deutlich unter 2°C, und idealerweise auf unter 1,5°C des vorindustriellen Niveaus zu begrenzen. Viele Länder haben ihre Zusage in das Ziel der Klimaneutralität (net-zero emissions) übertragen, und globale Bemühungen Emissionen zu reduzieren sind schrittweise erhöht worden. Allerdings wird der Temperaturanstieg unter der aktuellen Klimapolitik die angestrebten Ziele überschreiten. Die Umsetzung von Klimapolitikmaßnahmen, welche Emissionen reduzieren und kohlenstoffarme Innovationen fördern, ist dringend erforderlich, was ein Verständnis davon erfordert, welche klimapolitischen Instrumente und deren Gestaltungsoptionen effektiv Emissionen reduzieren. Ob die Umsetzung effektiver klimapolitischer Maßnahmen politisch durchsetzbar ist, hängt jedoch von politökonomischen Faktoren ab. Ein Verständnis der politischen Ökonomie von Energiewenden ist daher entscheidend für erfolgreiche Klimapolitik. Diese Dissertation untersucht das Zusammenspiel zwischen den Gestaltungsoptionen effektiver klimapolitischer Instrumente und der politischen Ökonomie ihrer Implementierung. Die vier Hauptkapitel dieser Dissertation analysieren die Auswirkungen marktwirtschaftlicher Klimapolitikinstrumente auf kohlenstoffarme Investitionen, wie politökonomische Faktoren den Bau von Kohlekraftwerken in mehreren Schwellenländern inklusive Indien beeinflussen, sowie die Narrative im beginnenden Diskurs um Wasserstoff. Die Kapitel beinhalten folgende zentrale Erkenntnisse: Erstens würde ein ausreichend hoher Mindestpreis in Emissionshandelssystemen zu höheren kohlenstoffarmen Investitionen führen, insbesondere von grünen Unternehmen, während fossile Investitionen energieintensiver Unternehmen abgeschafft würden. Zweitens wird der Bau weiterer Kohlekraftwerke maßgeblich von politischen Akteuren bestimmt, welche versuchen die Ziele Wirtschaftswachstum, ein stabiles Energiesystem und niedrige Energiepreise zu erreichen, wobei die politischen Entscheidungsträger* innen dabei dem Einfluss des Stromsektors unterliegen. Drittens reizen die Sicherstellung einer ausreichenden Stromversorgung und die langfristigen Verfügbarkeit von Strom private und öffentliche Kohleinvestitionen in Indien an, während regionale Kohlearbeitsplätze und lokale Interessen einen möglichen Kohleausstieg erschweren. Viertens teilen die Akteure des beginnenden Wasserstoffdiskurses das Ziel des Aufbaus einer Wasserstoffwirtschaft. Jedoch entstehen Konflikte darüber, in welchen Sektoren Wasserstoff eingesetzt werden soll, zu den geplanten Produktionsmethoden und der Bewertung von Importen. Aus den Ergebnissen leiten sich folgende Implikationen für weitere wissenschaftliche und politische Diskussionen ab: Ex-ante Daten von deutschen Energiemanager*innen legen nahe, dass ein Mindestpreis auf ausreichend hohem Niveau eine wichtige Erweiterung von Emissionshandelssystemen wäre. Die Ergebnisse ergänzen frühere ex-post Studien zur Effektivität des Europäischen Emissionshandelssystems, die bis zuletzt durch Daten aus Zeiträumen geringer Zertifikatspreise eingeschränkt waren, was Vorhersagen zu möglichen Auswirkungen höherer Preise erschwerte. Eine Expert*innenenbefragung zu politökonomischen Faktoren in wichtigen Kohleländern zeigt, dass es in allen Ländern gleichermaßen auftretende politökonomische Strukturen gibt, welche daher eine besondere Berücksichtigung in Diskussionen über globale Kohleausstiegsstrategien erfordern. Die Ergebnisse erweitern außerdem die bregrenzten Erkenntnisse zu der politischen Ökonomie in Schwellenländern. Detaillierte Einblicke durch Expert*inneninterviews zur indischen Energiepolitik legen nahe, dass regionale Kohleausstiegspläne, die sowohl eine gerechte Transition, als auch eine Umstrukturierung des Stromsystems gewährleisten, wichtige Maßnahmen zur Einleitung eines Kohleausstiegs sind. Zuletzt liefert die Analyse des beginnenden öffentlichen Diskurses um Wasserstoff auf Basis von deutschen Zeitungsartikeln erste empirische Erkenntnisse über die Narrative verschiedener Akteuren und legt den Grundstein für ein besseres Verständnis aktueller, sowie potenzieller zukünftiger Kontroversen. Ein einfacher konzeptioneller Rahmen leistet dabei einen Beitrag zur Theoriebildung von Transitionen zur Nachhaltigkeit, welche sich über mehrere Wirtschaftssektoren erstrecken. Insgesamt kombiniert diese Dissertation Erkenntnisse über die Gestaltung klimapolitischer Instrumente mit der der politischen Ökonomie von Kohle und Wasserstoff in verschiedenen geografischen Kontexten. Zwei Kapitel zu Deutschland untersuchen wie sich Gestaltungsoptionen der Kohlenstoffbepreisung auf kohlenstoffarme Investitionen von Unternehmen auswirken können, während die Analyse des Wasserstoffdiskurses unterstreicht, wie Narrative die öffentliche Wahrnehmung eines kohlenstoffarmen Energieträgers beeinflussen können. Die Ergebnisse heben die wichtige Rolle der Politik bei der Bestimmung wirtschaftlicher Anreize für kohlenstoffarme Investitionsentscheidungen hervor, aber auch, dass die Umsetzung von Energiepolitik stark umstritten und umkämpft sein kann. Weitere zwei Kapitel befassen sich mit der Kohlepolitik in verschiedenen Schwellenländern und insbesondere Indien, und heben die komplexen Herausforderungen von politischen Entscheidungsträger* innen in diesen Ländern hervor, die einen Kohleausstieg anstreben. Beide Kapitel umreißen den Zielkonflikt zwischen Umweltzielen und kurzfristigen Wirtschaftswachstums, verweisen jedoch auch auf die Rolle persönlicher Interessen und Lobbyismus. Gemeinsam zeigen alle Kapitel, dass ein Verständnis des Zusammenhangs von Politik und Politikinstrumenten von größter Bedeutung für eine erfolgreiche Eindämmung des Klimawandels sind.BMBF, 01LA1826C, PEGASOS - Modellierung und Szenarienanalyse

Frequency and duration of low-wind-power events in Germany

Abstract In the transition to a renewable energy system, the occurrence of low-wind-power events receives increasing attention. We analyze the frequency and duration of such events for onshore wind power in Germany, based on 40 years of reanalysis data and open software. We find that low-wind-power events are less frequent in winter than in summer, but the maximum duration is distributed more evenly between months. While short events are frequent, very long events are much rarer. Every year, a period of around five consecutive days with an average wind capacity factor below 10% occurs, and every ten years a respective period of nearly eight days. These durations decrease if only winter months are considered. The longest event in the data lasts nearly ten days. We conclude that public concerns about low-wind-power events in winter may be overrated, but recommend that modeling studies consider multiple weather years to properly account for such events.</jats:p

Effects of non-linearity on the flame response and control of combustion instabilities in a matrix burner

This paper discusses the effect of non-linearities inside a matrix burner on the flame response and control of instabilities inside the matrix burner. In particular, the response of the flame to high inlet velocity modulation level and frequency of the forcing signal are discussed. The importance of the choice of the combustion model used in the numerical simulation of combustion instabilities is highlighted. The effect of non-linearities on the choice of the primary fuel actuator used in active control is discussed. Finally, it is shown that the occurrence of limit cycle behavior inside the combustor of the matrix burner led to hysteresis. The analysis begins with the discussion of the stability map of the matrix burner obtained from measurements