Large-scale offshore wind production in the Mediterranean Sea

In recent years there has been a growing interest in offshore wind energy thanks to the various advantages it offers. The offshore wind energy is used for the production of electric energy above all in the shallow waters but different research activities and large-scale demonstrations are also under way for the deep waters with scientific and technological advances that open possibilities also for new markets such as the Mediterranean Sea. In this context, the present paper aims to estimate the large-scale offshore wind production of the Mediterranean Sea. The methodology uses an open GIS platform and considers bathymetric data, annual average wind speed data, environmental data, turbines technical characteristics and administrative information. Three depth categories have been considered. The overlap between depth categories and annual average wind speeds ranges has allowed to determine the areas potentially suitable for wind farms allocation. On the basis of optimal wind farm layouts and of the characteristic of the type of turbines considered, the theoretical maximum annual offshore wind production has been estimated for whole Mediterranean area and it is about 742 TWh/year. Moreover, for each depth category, the theoretical annual wind offshore production for each Mediterranean country has been estimated

03/13/1984 - Weather Not Cooperating With Softball

In the present paper, a formulation for the estimation of the wave transmission coefficient, Kt, at low-crested structures (LCS) is proposed based on a large laboratory database. The adopted database considers 2D experiments on wave transmission at LCS; it consists of 3327 values of Kt from 33 datasets and includes rubble mound structures with natural and concrete units, as well as impermeable slopes. According to Goda and Ahrens (2008), the wave transmission coefficient is formulated as the summation of the wave energy transmitted over and through LCS. Application of the new formulation showed a good agreement between measured and predicted K-t

08/07/2000 - EIU Students Receive Lord Scholarships

The Breaking Celerity Index (BCI) is proposed as a new wave breaking criterion for Boussinesq-type equations wave propagation models (BTE). The BCI effectiveness in determining the breaking initiation location has been verified against data from different experimental investigations conducted with incident regular and irregular waves propagating along uniform slope [Utku, M. (1999). "The Relative Trough Froude Number. A New Criteria for Wave Breaking". Ph.D. Dissertation, Dept. of Civil and Enviromental Engineering, Old Dominion University, Norfolk, VA: Gonsalves Veloso dos Reis, M.T.L. (1992). "Characteristics of waves in the surf zone". MS Thesis, Department of Civil Engineering, University of Liverpool., Liverpool; Lara. J.L., Losada, I.J., and Liu, P.L.-F. (2006). "Breaking waves over a mild gravel slope: experimental and numerical analysis". Journal of Geophysical Research, VOL 111. C11019] and barred beaches [Tomasicchio, G.R., and Sancho, F. (2002). "On wave induced undertow at a barred beach". Proceedings of 28th International Conference on Coastal Engineering, ASCE, New York, 557-569]. The considered experiments were carried out in small-scale and large-scale facilities. In addition, one set of data has been obtained by the use of the COBRAS model based upon the Reynolds Averaged Navier Stokes (RANS) equations [Liu, P.L.-F., Lin, P.. Hsu, T.. Chang, K., Losada, I.J.. Vidal, C., and Sakakiyama. T. (2000). "A Reynolds averaged Navier-Stokes equation model for nonlinear water wave and structure interactions". Proceedings of Coastal Structures '99, Balkema, Rotterdam, 169-174; Losada, I.J.. Lara, J.L., and Liu, P.L.-F. (2005). "Numerical simulation based on a RANS model of wave groups on an impermeable slope". Proceedings of Fifth International Symposium WAVES 2005. Madrid]. Numerical simulations have been performed with the 1D-FUNWAVE model [Kirby, J.T., Wei, G., Chen, Q.. Kennedy, A.B., and Dalrymple, R.A. (1998). "FUNWAVE 1.0 Fully Nonlinear Boussinesq Wave Model Documentation and User's Manual". Research Report No CACR-98-06, Center for Applied Coastal Research, University of Delaware, Newark]. With regard to the adopted experimental conditions, the breaking location has been calculated for different trigger mechanisms [Zelt, J.A. (1991). "The run-up of nonbreaking and breaking solitary waves". Coastal Engineering, 15, 205-246: Kennedy. A.B., Chen, Q, Kirby, J.T., and Dalrymple, R.A. (2000). "Boussinesq modeling of wave transformation, breaking and run-up. I: 1D".Journal of Waterway, Port, Coastal and Ocean Engineering, 126, 39-47: Utku, M., and Basco, D.R. (2002). "A new criteria for wave breaking based on the Relative Trough Froude Number". Proceedings of 28th International Conference on Coastal Engineering. ASCE, New York, 258-268] including the proposed BCI. The calculations have shown that BCI gives a better agreement with the physical data with respect to the other trigger criteria, both for spilling and plunging breaking events, with a not negligible reduction of the calculation time

Spar buoy numerical model calibration and verification

The present paper describes the experiences gained from the design methodology and operation of a 3D physical model experiment aimed to investigate the dynamic behavior of a spar buoy (SB) off-shore floating wind turbine (WT) under different wind and wave con- ditions. The physical model tests have been performed at Danish Hydraulic Institute (DHI) off-shore wave basin within the European Union-Hydralab IV Integrated Infrastructure Initiative, in October 2012. The floating WT model has been subjected to a combination of regular and irregular wave attacks and steady wind loads. Observations of hydrodynamics, displacements of the floating structure, wave induced pressures and tensions at critical points of the structure and at the mooring lines have been carried out. Based on the observed data, the numerical model Sesam [1], developed by Det Norske Veritas (DNV), has been calibrated and verified. The adopted numerical model took into account the wave induced response and the effects of the mooring lines on the overall system. The calibration of the numerical model has been performed both for static and dynamic condi- tions. At the end of the calibration procedure, the numerical model has been successfully used to simulate two selected irregular wave attacks

Simple wave breaking depth index formula for regular waves

A simple formula to determine the wave breaking depth index for regular waves is proposed. In the literature, there are several formulas for determining the breaker depth index, which, over the years, have gradually evolved by improving advanced measurement tools. The proposed formula has been obtained by means of dimensional analysis and incomplete self-similarity, and it has been calibrated and verified by using a large breaker depth index database yield fairing good predictions for a wide range of wave conditions and beach slopes. The application of some existing formulas for determining the breaker depth index has been examined by using previous published laboratory data compared with the new formula

Recent improvements for estimation of longshore transport

Sempre pi\uf9 frequentemente, la preservazione dei paesaggi costieri, di centri urbani, di infrastrutture per la viabilit\ue0 o dell'industria del turismo balneare pone la necessit\ue0 di ricorrere ad interventi di ripascimento delle spiagge soggette ad erosione. La longevit\ue0 degli interventi talvolta non risulta adeguatamente commisurata al costo sostenuto per la loro attuazione: non \ue8 raro che interventi di ripascimento, protetti o non, si depauperino in un breve lasso di tempo seguente alla esecuzione del lavoro, vanificando cos\uec l'investimento. Pertanto, negli ultimi anni, il progettista di un intervento di difesa della spiaggia dall'erosione tende a valutare la possibilit\ue0 di effettuare il ripascimento artificiale di spiagge soggette ad erosione mediante l'impiego di materiali pi\uf9 grossolani rispetto alla sabbia nativa; tanto al fine di ottenere una spiaggia composta da elementi dotati di una maggiore stabilit\ue0 idraulica rispetto a quelli della spiaggia originaria, a parit\ue0 di condizioni di moto ondoso presenti nell'area di interesse. Tra gli altri, anche le Linee Guida per la difesa delle coste basse della Regione Puglia denominate "Individuazione di strutture di mitigazione del rischio per ciascuna unit\ue0 fisiografica" invitano il progettista all'utilizzo di ghiaie o ciottoli per il ripascimento di arenili, tanto allo scopo di incrementare la longevit\ue0 degli assai dispendiosi interventi a mare. Tuttavia, a tale condivisibile indicazione che giunge dagli Enti regolatori non corrisponde una adeguata risposta da parte del tecnico professionista. Ed infatti, mentre per il caso delle spiagge in sabbia esiste una ragguardevole conoscenza, la comunit\ue0 scientifica e professionale avverte l'assenza di criteri e metodi in grado di valutare i volumi di materiale che vengono mobilizzati dall'azione del moto ondoso che interagisce con una spiaggia, anche se questa \ue8 formata da materiali che non siano sabbia; in particolare, la necessit\ue0 di poter disporre di mezzi di calcolo che non siano limitati al solo caso delle spiagge in sabbia \ue8 maggiormente avvertita per la determinazione del trasporto litoraneo di ghiaie, ciottoli e spiagge miste (sabbia, ghiaie e ciottoli). Il presente studio intende dare un contributo al tema del calcolo del trasporto litoraneo per spiagge composte da materiali pi\uf9 grossolani rispetto alla sabbia. In particolare, \ue8 stata condotta la verifica delle capacit\ue0 del modello GLT (Tomasicchio et alii, 2013) nella stima del trasporto litoraneo per spiagge in ciottoli e spiagge miste. Il modello GLT adotta un approccio del tipo a flusso di energia, combinato con una relazione di tipo empirico/statistico tra la forzante, rappresentata dal moto ondoso incidente, e il numero di elementi che subiscono lo spostamento; GLT assume l'ipotesi che gli elementi che compongono la spiaggia si muovono, durante le fasi di risalita e discesa dell'onda lungo la battigia, con obliquit\ue0 pari a quella delle onde frangenti e riflesse in corrispondenza della profondit\ue0 di frangimento. Allo scopo \ue8 stata verificata la appropriatezza del modello GLT nella quantificazione del trasporto litoraneo per il caso di spiagge in ciottoli. In particolare, la verifica \ue8 stata condotta, evitando qualsiasi tipo di taratura preventiva, mediante il confronto tra i risultati del modello e i dati osservati in campo (Chadwick, 1989; Nicholls & Wright, 1991); il confronto tra il dato osservato e il dato calcolato ha mostrato che il modello GLT \ue8 in grado di predire i dati del trasporto osservati con un'approssimazione limitata ad un fattore 2. Al fine di introdurre ulteriori termini di raffronto per il modello GLT, la sua capacit\ue0 di calcolo \ue8 stata verificata favorevolmente anche rispetto ad un'altra formula generale per la stima del trasporto lungo spiagge composte da ciottoli (Van Rijn, 2014). Infine, passando ad un caso non raro in natura, ma anzi assai diffuso lungo le coste della Nuova Zelanda, dell'Inghilterra, dell'Iran, della Russia o della Calabria, l'affidabilit\ue0 del modello GLT \ue8 stata accertata anche per il caso delle spiagge composte da sabbie, ghiaie e ciottoli (miste); tale seconda verifica \ue8 stata resa possibile dalla disponibilit\ue0 di dati di letteratura osservati in campo per spiaggia mista e spiaggia in ghiaia nella baia di Hawke's Bay, lungo la costa est della Nuova Zelanda (Komar, 2010). A seguito della verifica favorevole del modello GLT condotta per il caso di spiagge in ciottoli e miste, \ue8 possibile sostenerne la possibilit\ue0 di impiego per il caso di progettazione di interventi di ripascimento per i quali si intenda utilizzare materiali pi\uf9 grossolani rispetto alla sabbia. E' anche possibile ipotizzare l'utilizzo del modello nello sviluppo di modelli di previsione della evoluzione nel tempo della linea di riva per spiagge composte da ciottoli o di tipo misto.In the present study, the accuracy of the GLT model (Tomasicchio et alii, 2013) has been verified for the estimation of the Longshore Transport (LT) at shingle and mixed beaches. In order to verify the suitability of the GLT model in determining LT estimates at shingle beaches, without any further calibration, the comparison between the LT predictions and observations from two field data sets (Chadwick, 1989; Nicholls & Wright, 1991) has been considered. The comparison showed that the GLT predicted LT rates within a factor of 2 of the observed values. The predictive capability of the GLT has been also verified against an alternative general formula for the LT estimation at shingle beaches (Van Rijn, 2014). In addition, the suitability of the GLT model, even for the mixed beach case, has been assessed by means of the comparison between the LT prediction and the observation from a field experiment on a mixed sand and gravel beach at Hawke's Bay, on the east coast of New Zealand (Komar, 2010)

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries