Analysis of North Sea offshore wind power variability

This paper evaluates, for a 2030 scenario, the impact on onshore power systems in terms of the variability of the power generated by 81 GW of offshore wind farms installed in the North Sea. Meso-scale reanalysis data are used as input for computing the hourly power production for offshore wind farms, and this total production is analyzed to identify the largest aggregated hourly power variations. Based on publicly available information, a simplified representation of the coastal power grid is built for the countries bordering the North Sea. Wind farms less than 60 km from shore are connected radially to the mainland, while the rest are connected to a hypothetical offshore HVDC (High-Voltage Direct Current) power grid, designed such that wind curtailment does not exceed 1% of production. Loads and conventional power plants by technology and associated cost curves are computed for the various national power systems, based on 2030 projections. Using the MATLAB-based MATPOWER toolbox, the hourly optimal power flow for this regional hybrid AC/DC grid is computed for high, low and medium years from the meso-scale database. The largest net load variations are evaluated per market area and related to the extra load-following reserves that may be needed from conventional generators.Parts of this work were funded by Agentschap.NL, the Netherlands, now RVO.nl (Rijksdienst voor Ondernemend Nederland [25], under the project North Sea Transnational Grid (NSTG). The NSTG project is a cooperation between Delft University of Technology and the Energy Research Center of the Netherlands

Discussion and reply : the Cambrian System in Northwestern Argentina : stratigraphical and palaeontological framework Discussion

As part of the Special Issue on "Advances in the knowledge of the Cambrian System" edited by himself, Aceñolaza (2003) attempted to summarize present knowledge on the Cambrian of northwest Argentina. Althoughhe is congratulated for tackling such a complex topic, wewould like to take advantage of Geologica Acta as aforum for discussion to address some issues that remain unclear and to advance alternative ideas, providing pertinent additional literature. We will discuss these aspects by referring to the three most important stratigraphic units thatinclude Cambrian rocks in northwest Argentina, the Puncoviscana Formation, the Mesón Group and the Santa Rosita Formation. Aspects addressed are tectonic setting, stratigraphic relations, age and depositional environment. Trace fossil data included in the appendix are briefly reviewed

Biofilm Harvesters in Coastal Settings of the Early Palaeozoic

The ichnogenera Syringomorpha and Daedalus are here interpreted as products of infaunal biofilm harvesters. This study investigated: (1) Syringomorpha nilssoni and Syringomorpha isp. from the Cambrian Series 2‐Miaolingian Campanario Formation, northwest Argentina; and (2) Daedalus halli from the Floian Grès et Schistes de la Cluse de l’Orb Formation, Montagne Noire, France. Syringomorpha nilssoni occurs in sandy to mixed intertidal to lower shoreface deposits, whereas Syringomorpha isp. in the lower intertidal zone. Daedalus halli occurs in a lagoon and intertidal to lower shoreface sands of a barrier island. Syringomorpha and Daedalus comprise a vertical J‐shaped causative burrow and deep spreite. These ichnotaxa form monospecific assemblages (bioturbation index BI = 3–5) in quartzose medium‐ to fine‐grained sandstone, recording colonization in high‐energy tide‐and wave‐dominated settings. Lower abundances (BI = 1–2) are observed in silty sandstone. The abundance of both ichnogenera in mature sandstone is inconsistent with a classic deposit‐feeding strategy because ‘clean’ sediments are commonly impoverished of organic detritus, this being particularly true in Cambro‐Ordovician littoral settings lacking terrestrial plant detritus. Based on morphology, host sediment properties and comparison with modern structures, such those produced on intertidal and shallow subtidal setting by Arenicola marina and Paraonis fulgens, it is suggested that the diet of Syringomorpha and Daedalus producers may have consisted of biofilms colonising sand grains, associated eukaryotic microbes, and possibly meiofauna. Whereas Syringomorpha is a product of the Cambrian explosion, Daedalus is associated with the Ordovician Radiation. In contrast to most ichnotaxa, which display long temporal ranges, these two ichnogenera are restricted to the Cambrian and Ordovician‐Silurian, respectively. The underlying reasons for the relatively restricted stratigraphic ranges of these ichnotaxa are unclear, but space competition, and increased predation pressure may have played a role. The feeding strategy of the Daedalus and Syringomorpha producers was less efficient than suspension feeding and passive predation, trophic types epitomized by the dominant macroinfauna that persisted in water‐agitated nearshore sands during the rest of the Phanerozoic

Sedimentology and Ichnology of Paleozoic Estuarine and Shoreface Reservoirs, Morrow Sandstone, Lower Pennsylvanian of Southwest Kansas, USA

Integration of facies and trace-fossil evidence tests and refines depositional models constructed solely on the basis of physical sedimentology. In recent years, the petroleum industry has increasingly used trace-fossil analysis of cores as an aid in reservoir characterization. In particular, ichnologic data have been instrumental in the recognition of estuarine deposits and their distinction from open-marine facies (e.g., MacEachern and Pemberton, 1994). Previous ichnologic analyses of cores, however, have concentrated on post-Paleozoic reservoirs (e.g., Bockelie, 1991; Pemberton, 1992; Taylor and Gawthorpe, 1993; Howell et al., 1996; Martin and Pollard, 1996; MacEachern and Pemberton, 1997). The present study represents one of the first attempts to apply trace-fossil analysis to cores from Paleozoic reservoirs. The Lower Pennsylvanian Morrow Sandstone contains oil and gas reservoirs in a wide variety of shallow and marginal-marine depositional environments. Delta-front, shoreface, and estuarine valley-fill reservoir sandstones are encased in offshore and estuarine mudstones (Sonnenberg, 1985; Krystinik and Blakeney, 1990; Sonnenberg et al., 1990; Wheeler et al., 1990). An integrated stratigraphic, sedimentologic, and ichnologic study provides a more accurate characterization of reservoir facies and geometry. This study allows distinction between marine-shoreface and estuarine valley-fill sandstones from four cores of the lower Morrow in southwestern Kansas. Core analysis subsequently was integrated with well-log information. Previous studies have emphasized the presence of estuarine valley-fills in the upper Morrow (Wheeler et al., 1990). Our integrated approach extends the estuarine valley interpretation into the lower Morrow. Within the midcontinent, trace fossils are useful in distinguishing different facies in estuarine incised valleys and marine shorefaces. Detailed study of biogenic structures provides high-resolution information to solve problems in facies, stratigraphic, and reservoir modeling. In some cases, they represent the only evidence available to develop a reasonable picture of depositional conditions and to estimate reservoir heterogeneity. The present study provides a detailed analysis of the sedimentary facies, documents the associated trace fossils, and illustrates how trace fossils are used to refine environmental interpretations of the lower Morrow sandstone reservoirs

Trace fossils, water table and depositional evolution in eolian systems (Cretaceous Mulichinco Formation, subsurface of western Argentina)

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Continental invertebrate and plant trace fossils in space and time: State of the art and prospects

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Late Cambrian – Tremadocian faunas and events from Angosto del Moreno Section, Eastern Cordillera, Argentina

The Santa Victoria Group (SVG, late Upper Cambrian – Caradocian) comprises pre–Ashgillian Ordovician deposits of the Argentinean Eastern Cordillera. The most significant section of the SVG in the western flank of the Eastern Cordillera is located in the Angosto del Moreno area (Figure 1a, b). At this locality, the SVG unconformably overlies the Mesón Group (Cambrian s.l.), and unconformably underlies Cretaceous rocks (Yacoraite Formation). Upper Cambrian to lower Lower Ordovician units are separated from upper Lower to Middle Ordovician units (Parcha and Sepulturas formations) by the Tumbaya unconformity (Figure 2). The Angosto del Moreno Section of the SVG is exceptional in terms of the quality of exposures, continuity of deposits, richness of fossils, and accessibility. Diverse aspects concerning the Ordovician geology of this study area have been discussed by Moya et al. (1994, 1998), Moya and Albanesi (2000), Moya and Monteros (2000), Malanca and Brandán (2000), and Gómez Martínez et al. (2002). Previous data and recent paleontological collections enable a preliminary biostratigraphic scheme (Figure 2) for the Upper Cambrian to Tremadocian units of the SVG. A synthesis of the sequence stratigraphy and depositional environments of these units is given by Buatois et al. (this volume).Fil: Moya, Maria Cristina. Universidad Nacional de Salta. Consejo de Investigacion; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Malanca, Susana. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Monteros, Julio A.. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Albanesi, Guillermo Luis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ortega, Gladys del Carmen. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Buatois, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentin

The Angosto del Moreno area, Eastern Cordillera, Jujuy province

Ordovician and Silurian rocks exposed in the western belt of the Eastern Cordillera of Jujuy Province will be discussed during the journey through the provincial road 16, which connects the Purmamarca Village with the Angosto del Moreno locality. Following stops refer to diverse geological aspects of the region.Fil: Moya, Maria Cristina. Universidad Nacional de Salta. Consejo de Investigacion; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; ArgentinaFil: Malanca, Susana. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Monteros, Julio A.. Universidad Nacional de Salta. Consejo de Investigacion; ArgentinaFil: Albanesi, Guillermo Luis. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ortega, Gladys del Carmen. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Museo de Paleontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Buatois, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Correlación Geológica. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Geología. Cátedra Geología Estructural. Instituto Superior de Correlación Geológica; Argentin

High-resolution computed tomography reconstructions of invertebrate burrow systems

The architecture of biogenic structures can be highly influential in determining species contributions to major soil and sediment processes, but detailed 3-D characterisations are rare and descriptors of form and complexity are lacking. Here we provide replicate high-resolution micro-focus computed tomography (μ-CT) data for the complete burrow systems of three co-occurring, but functionally contrasting, sediment-dwelling inter-tidal invertebrates assembled alone, and in combination, in representative model aquaria. These data (≤2,000 raw image slices aquarium−1, isotropic voxel resolution, 81 μm) provide reference models that can be used for the development of novel structural analysis routines that will be of value within the fields of ecology, pedology, geomorphology, palaeobiology, ichnology and mechanical engineering. We also envisage opportunity for those investigating transport networks, vascular systems, plant rooting systems, neuron connectivity patterns, or those developing image analysis or statistics related to pattern or shape recognition. The dataset will allow investigators to develop or test novel methodology and ideas without the need to generate a complete three-dimensional computation of exemplar architecture

The ichnologic signature of deep-sea colonization during the Ordovician radiation

The fossil record of deep-marine environments is notoriously poor in comparison with that of their shallow-marine counterparts. Notably, deep-marine deposits are typically host to diverse and abundant trace-fossil assemblages, providing evidence of the ancient deep-sea benthos. To analyze the early colonization of the deep sea, we constructed a global dataset of trace-fossil occurrences from a survey of EdiacaranâDevonian stratigraphic units. This analysis highlights the importance of the Ordovician radiation as a pivotal time in the colonization of the deep sea. Ediacaran deep-marine trace fossils consist of very simple trails and burrows. Global and alpha ichnodiversity, as well as ichnodisparity, were extremely low. Nonspecialized grazing trails reveal the exploitation of microbial mats. These strategies persisted in the Cambrian, although with an increase in ichnodiversity (both global and alpha) and ichnodisparity. An increase in the complexity of morphologic patterns, as illustrated by the undermat mining ichnogenus Oldhamia, is apparent during the Cambrian. The face of the deep sea started to change during the end of the Cambrian and beginning of the Ordovician with the protracted expansion of farming and trapping strategies. The main architectural designs of deep-marine trace fossils (e.g. regular networks, delicate spiral burrows, guided meandering graphoglyptids) were established in the deep sea by the Early Ordovician, recording the first appearance of the Nereites Ichnofacies. Lower to Middle Ordovician deep-marine ichnofaunas are moderately diverse, and fodinichnia commonly dominates rather than graphoglyptids. A significant ichnodiversity and ichnodisparity increase occurred in the Late Ordovicianâearly Silurian, with ichnofaunas recording higher proportions of graphoglyptids and evidencing the establishment of a deep-marine ecosystem of modern aspect. The distinction between the Nereites and Paleodictyon ichnosubfacies, with the former characterized by the dominance of feeding traces in muddy turbidites and the later by the dominance of graphoglyptids in sandy turbidites, can also be tracked back to the Ordovician radiation. This trend of increased colonization of the deep sea continued through all the Silurian and the Devonian. However, colonization of carbonate turbidites may have lagged behind that of siliciclastic turbidites. The progressive increase in abundance and diversity of graphoglyptids resulted in an increased role of gallery biodiffusers. This faunal turnover in the deep sea was coincident with an increase in oxygenation in slope and base-of-slope settings, which is thought to have been a driver of Ordovician biodiversifications. The formation of permanent open burrows in the deep sea may have increased bioirrigation in the uppermost zone of the deep-sea sediment, therefore increasing ventilation and potentially generating a feedback loop between bioturbation and oxygenation, with the endobenthos engineering its environment