Wind power integration, negative prices and power system flexibility - An empirical analysis of extreme events in Germany

This article analyses the flexibility of the German power market with respect to the integration of an increasing share of electricity from renewable energy sources. Flexibility limiting system components, which cause negative prices are explained and illustrated for the German market. Then, the decision of the European Energy Exchange in Leipzig (EEX) to allow negative price bids is explained. Empirical data show the flexibility of conventional generating capacities in Germany during the considered time frame from October 2008 until November 2009. Of the 71 hours with negative spot prices, ten hours were significantly negative with prices of at least -100€/MWh. These extreme hours are analysed in greater detail by the examination of the different system components. Thereby, load, wind power infeed and conventional generation by fuel type are observed as well as the market for negative tertiary reserve as indicators for market tightness. It will be shown that although the market situations were severe, under current conditions it could have been much worse under certain circumstances. Furthermore, the long-run implications of an increasing RES-E share on the conventional generation capacity are discussed. The article concludes with an outlook on additional power system flexibility options.Electricity markets, negative prices, renewable electricity integration, wind power

The impact of RES-E policy setting on integration effects - A detailed analysis of capacity expansion and dispatch results

The operation of the power markets is strongly aected by the presence of high shares of electricity from renewable energy sources (RES-E) in the market. Especially in times of high RES-E infeed, rm market situations can lead to extreme results, even to negative power prices. The behavior of RES-E in potential oversupply situations depends on the RES-E support scheme and in particular on the dened curtailment rules. By now, dierent curtailment rules have not been taken into account in long-run capacity expansion analyses. The present research investigates the impact of curtailment rules on the operation and the investment decisions through the utilization of "The High Temporal Resolution Electricity Market Analysis Model" (THEA) for the German power market under consideration of the neighboring countries. In general the results show that RES-E can provide exibility to the system if low burdens for curtailment are applied. This comes with the cost of lacking market signals which could trigger investments in exible generation capacities. However, if RES-E are forced into the market at any cost, the burden for consumers increases and the market signals high demand for alternative exibilities.Power market modeling, RES-E integration, curtailment rules

Transition in place: dynamics, possibilities, and constraints

The Transition Movement is a translocal phenomenon circulated through transnational grassroots networks. This study explores the geographies of the Transition Movement with a theoretical framework that perceives it as both a social movement and a grassroots innovation. Participant-observation of Transition Salt Lake (TSL), located in the suburban metropolis of Salt Lake City, Utah, was conducted, as the United States remains a largely understudied country in regards to this particular movement. In this pursuit, we asked: (i) how and what this transition initiative draws from geographically extensive and intensive relations, (ii) how it combines place-specific elements and generalized models (embeddedness), and (iii) how this impacts the success of the transition initiative and how these impacts (positive or negative) are generated. Place, space, and scale played a large role in defining the nature, dynamics, possibilities, and constraints of this transition initiative. Specifically, geographically intensive and extensive relations were critical for the mobilization of complementary resources. The Transition model was found to be flexible, allowing for the initiative to adopt those elements that worked in place and to focus on locally relevant topics. TSL faced many challenges identified by previous researchers regarding finances, participation, diversity, and intragroup competition. While networking with other similar groups, TSL demonstrated that fertile environments of activism are incubatory pools for grassroots innovations and social movements, and a trade-off was found with competition for resources between local groups

The decision problem for a three-sorted fragment of set theory with restricted quantification and finite enumerations

We solve the satisfiability problem for a three-sorted fragment of set theory (denoted $3LQST_0^R$), which admits a restricted form of quantification over individual and set variables and the finite enumeration operator $\{\text{-}, \text{-}, \ldots, \text{-}\}$ over individual variables, by showing that it enjoys a small model property, i.e., any satisfiable formula $\psi$ of $3LQST_0^R$ has a finite model whose size depends solely on the length of $\psi$ itself. Several set-theoretic constructs are expressible by $3LQST_0^R$-formulae, such as some variants of the power set operator and the unordered Cartesian product. In particular, concerning the unordered Cartesian product, we show that when finite enumerations are used to represent the construct, the resulting formula is exponentially shorter than the one that can be constructed without resorting to such terms

Do individual investors learn from their trading experience

This paper investigates whether individual investors adjust their stock trading according to their stock selection abilities, which can be inferred from their trading history. Fixed-effect panel regressions provide strong evidence that the ability to forecast future stock returns significantly affects investors’ trading activity: investors purchase more actively if they are more likely to have stock selection ability. Furthermore, trading experience – measured by the number of purchases, the number of different stocks purchased, and the variance of purchase dollar amounts – significantly helps improve investors’ portfolio performance. In addition, we find that learning behavior varies across investors, which corroborates the heterogeneity of individual investorsindividual investors, learning, rationality, trading

Hedging error in Lévy models with a Fast Fourier Transform approach

We measure, in terms of expectation and variance, the cost of hedging a contingent claim when the hedging portfolio is re-balanced at a discrete set of dates. The basic point of the methodology is to have an integral representation of the payoff of the claim, in other words to be able to write the payoff as an inverse Laplace transform. The models under consideration belong to the class of Lévy models, like NIG, VG and Merton models. The methodology is implemented through the popular FFT algorithm, used by many financial institutions for pricing and calibration purposes. As applications, we analyze the effect of increasing the number of tradings and we make some robustness tests.Hedging, Lévy models, Fast Fourier Transform

Loss induced collective subradiant Dicke behaviour in a multiatom sample

The exact dynamics of $N$ two-level atoms coupled to a common electromagnetic bath and closely located inside a lossy cavity is reported. Stationary radiation trapping effects are found and very transparently interpreted in the context of our approach. We prove that initially injecting one excitation only in the $N$ atoms-cavity system, loss mechanisms asymptotically drive the matter sample toward a long-lived collective subradiant Dicke state. The role played by the closeness of the $N$ atoms with respect to such a cooperative behavior is brought to light and carefully discussed.Comment: 14 pages, 6 figures, submitted to EPJ