Valuation of wind energy projects: A real options approach

27 p.

Análisis de precios del mercado diario de electricidad español

El trabajo analiza los precios de la electricidad del mercado diario español. En el mismo se realiza un estudio del mercado eléctrico español y sus componentes junto con un análisis de los cambios regulatorios más significativos durante el periodo muestral. A partir de allí, se analiza la muestra a través de los estadísticos descriptivos principales. Luego se presenta un modelo general que es analizado a partir de los resultados empíricos principales obtenidos con su estimación. Finalmente, se realizan ajustes al mismo para obtener un modelo simplificado que se ajuste mejor a lo que se quiere conseguir, que es analizar la evolución de los precios de la electricidad. Los resultados del ajuste arrojan que los precios horarios dependen en su mayor parte de los precios de las horas anteriores. También que el modelo recoge muy bien la estacionalidad mensual y horaria que presenta la muestra. Por otro lado, características de la serie de precios como son la volatilidad y los saltos no quedan bien recogidos por el modelo, lo que lleva a plantearse la búsqueda de modelos alternativos.

Análisis de precios del mercado diario de electricidad español

El trabajo analiza los precios de la electricidad del mercado diario español. En el mismo se realiza un estudio del mercado eléctrico español y sus componentes junto con un análisis de los cambios regulatorios más significativos durante el periodo muestral. A partir de allí, se analiza la muestra a través de los estadísticos descriptivos principales. Luego se presenta un modelo general que es analizado a partir de los resultados empíricos principales obtenidos con su estimación. Finalmente, se realizan ajustes al mismo para obtener un modelo simplificado que se ajuste mejor a lo que se quiere conseguir, que es analizar la evolución de los precios de la electricidad. Los resultados del ajuste arrojan que los precios horarios dependen en su mayor parte de los precios de las horas anteriores. También que el modelo recoge muy bien la estacionalidad mensual y horaria que presenta la muestra. Por otro lado, características de la serie de precios como son la volatilidad y los saltos no quedan bien recogidos por el modelo, lo que lleva a plantearse la búsqueda de modelos alternativos.

Mechanisms involved in Escherichia coli and Serratia marcescens removal during activated sludge wastewater treatment

Wastewater treatment reduces environmental contamination by removing gross solids and mitigating the effects of pollution. Treatment also reduces the number of indicator organisms and pathogens. In this work, the fates of two coliform bacteria, Escherichia coli and Serratia marcescens, were analyzed in an activated sludge process to determine the main mechanisms involved in the reduction of pathogenic microorganisms during wastewater treatment. These bacteria, modified to express green fluorescent protein, were inoculated in an activated sludge unit and in batch systems containing wastewater. The results suggested that, among the different biological factors implied in bacterial removal, bacterivorous protozoa play a key role. Moreover, a representative number of bacteria persisted in the system as free-living or embedded cells, but their distribution into liquid or solid fractions varied depending on the bacterium tested, questioning the real value of bacterial indicators for the control of wastewater treatment process. Additionally, viable but nonculturable cells constituted an important part of the bacterial population adhered to solid fractions, what can be derived from the competition relationships with native bacteria, present in high densities in this environment. These facts, taken together, emphasize the need for reliable quantitative and qualitative analysis tools for the evaluation of pathogenic microbial composition in sludge, which could represent an undefined risk to public health and ecosystem functions when considering its recycling.

Hitzarmen kolektiboen ultraktibitatearen desagerpena

[EU]Lan erreforma indarrean sartu arte, hitzarmen kolektiboen negoziazioen porrotak, aurreko hitzarmenak indarraldia mantentzen jarraitzen zuela zekarren kontrako akordiorik egon ezean. Egun ordea, indarraldi hori urtebetera mugatu egiten da, eta hala, behin epe hori igarota eraginkortasuna galduko du, kontrako akordiorik ez badago, eta beraz, goragoko hitzarmena aplikatuko da (existitzen bada). Erreforma honek, hitzarmenen birnegoziazioa sustatzea eta lan baldintzen petrifikaziorik ez gertatzea du helburu. Baina, araudi berriak, interpretazio arazo ugari sortzen dituenez, lan honekin, eman daitezkeen erantzun posibleak landuko ditugu; eta auzitegiek zein irizpide jarraitu duten aztertuko da. Hitz gakoak: hitzarmen kolektiboa, ultraktibitatea, indarraldia, goragoko hitzarmen kolektiboa.

Valuation of Wind Energy Projects: A Real Options Approach

We address the valuation of an operating wind farm and the finite-lived option to invest in it under different reward/support schemes: a constant feed-in tariff, a premium on top of the electricity market price (either a fixed premium or a variable subsidy such as a renewable obligation certificate or ROC), and a transitory subsidy, among others. Futures contracts on electricity with ever longer maturities enable market-based valuations to be undertaken. The model considers up to three sources of uncertainty: the electricity price, the level of wind generation, and the certificate (ROC) price where appropriate. When analytical solutions are lacking, we resort to a trinomial lattice combined with Monte Carlo simulation; we also use a two-dimensional binomial lattice when uncertainty in the ROC price is considered. Our data set refers to the UK. The numerical results show the impact of several factors involved in the decision to invest: the subsidy per MWh generated, the initial lump-sum subsidy, the maturity of the investment option, and electricity price volatility. Different combinations of variables can help bring forward investments in wind generation. One-off policies, e.g., a transitory initial subsidy, seem to have a stronger effect than a fixed premium per MWh produced.

From Gods to men: A historical overview of the discovery of the chemical elements

To achieve the apparently simple Periodic Table of the Elements has implied tremendous efforts over thousands of years. In this paper we present a brief history of the discovery of the chemical elements from prehistory to the present day, revealing the controversies that arose on the way and claiming the important work performed by alchemists in the advancement of knowledge. This is especially important if we consider that alchemy had a period of existence of many thousands of years, while the "Chemistry", officially established as a science in the eighteenth century, has operated as such for only a few hundred years. Even so, if we consider the progress of discovery and isolation of chemical elements throughout history, it can be observed that the number of elements identified is achieved mainly in the nineteenth and twentieth centuries, reflecting the development of instrumental techniques, that facilitated this task.

Hermenéutica de la astrología greco-romana

[ES] La astrología grecorromana es un código lingüístico con signos (planetas, signos del Zodíaco), y con leyes de interconexión entre ellos (eclíptica, aspectos, casas, límites), y ha de ser valorada no sólo desde la perspectiva de su cientificidad, sino desde la de sus funciones para el individuo y la sociedad: es un conocimiento del futuro singular que afecta a la totalidad de lo implicado, y en la totalidad de sus dimensiones. Suple así el conocimiento de la ciencia antigua, que no fue capaz de incluir ni lo futuro ni lo singular. La astrología integra al individuo en la comunidad, integrándolo previamente en su universo semántico. Cosmos, mundo humano y mundo natural se armonizan totalmente.

Lethal Interpersonal Violence in the Middle Pleistocene

Evidence of interpersonal violence has been documented previously in Pleistocene members of the genus Homo, but only very rarely has this been posited as the possible manner of death. Here we report the earliest evidence of lethal interpersonal violence in the hominin fossil record. Cranium 17 recovered from the Sima de los Huesos Middle Pleistocene site shows two clear perimortem depression fractures on the frontal bone, interpreted as being produced by two episodes of localized blunt force trauma. The type of injuries, their location, the strong similarity of the fractures in shape and size, and the different orientations and implied trajectories of the two fractures suggest they were produced with the same object in face-to-face interpersonal conflict. Given that either of the two traumatic events was likely lethal, the presence of multiple blows implies an intention to kill. This finding shows that the lethal interpersonal violence is an ancient human behavior and has important implications for the accumulation of bodies at the site, supporting an anthropic origin.