Hydrodynamic induced by an array of wave energy converters. Experimental and numerical analysis

The thesis analyses the hydrodynamic induced by an array of Wave energy Converters (WECs), under an experimental and numerical point of view. WECs can be considered an innovative solution able to contribute to the green energy supply and –at the same time– to protect the rear coastal area under marine spatial planning considerations. This research activity essentially rises due to this combined concept. The WEC under exam is a floating device belonging to the Wave Activated Bodies (WAB) class. Experimental data were performed at Aalborg University in different scales and layouts, and the performance of the models was analysed under a variety of irregular wave attacks. The numerical simulations performed with the codes MIKE 21 BW and ANSYS-AQWA. Experimental results were also used to calibrate the numerical parameters and/or to directly been compared to numerical results, in order to extend the experimental database. Results of the research activity are summarized in terms of device performance and guidelines for a future wave farm installation. The device length should be “tuned” based on the local climate conditions. The wave transmission behind the devices is pretty high, suggesting that the tested layout should be considered as a module of a wave farm installation. Indications on the minimum inter-distance among the devices are provided. Furthermore, a CALM mooring system leads to lower wave transmission and also larger power production than a spread mooring. The two numerical codes have different potentialities. The hydrodynamics around single and multiple devices is obtained with MIKE 21 BW, while wave loads and motions for a single moored device are derived from ANSYS-AQWA. Combining the experimental and numerical it is suggested –for both coastal protection and energy production– to adopt a staggered layout, which will maximise the devices density and minimize the marine space required for the installation

Evaluation of the power production performance of the wavepiston, wave energy converter

In the early 1970 the community has started to realize that have as a main principle the industry one, with the oblivion of the people and health conditions and of the world in general, it could not be a guideline principle. The sea, as an energy source, has the characteristic of offering different types of exploitation, in this project the focus is on the wave energy. Over the last 15 years the Countries interested in the renewable energies grew. Therefore many devices have came out, first in the world of research, then in the commercial one; these converters are able to achieve an energy transformation into electrical energy. The purpose of this work is to analyze the efficiency of a new wave energy converter, called WavePiston, with the aim of determine the feasibility of its actual application in different wave conditions: from the energy sea state of the North Sea, to the more quiet of the Mediterranean Sea. The evaluation of the WavePiston is based on the experimental investigation conducted at the University of Aalborg, in Denmark; and on a numerical modelling of the device in question, to ascertain its efficiency regardless the laboratory results. The numerical model is able to predict the laboratory condition, but it is not yet a model which can be used for any installation, in fact no mooring or economical aspect are included yet. È dai primi anni del 1970 che si è iniziato a capire che il solo principio dell’industria con l’incuranza delle condizioni salutari delle persone e del mondo in generale non poteva essere un principio guida. Il mare, come fonte energetica, ha la caratteristica di offrire diverse tipologie di sfruttamento, in questo progetto è stata analizzata l’energia da onda. Negli ultimi 15 anni sono stati sempre più in aumento i Paesi interessati in questo ambito e di conseguenza, si sono affacciati, prima nel mondo della ricerca, poi in quello commerciale, sempre più dispositivi atti a realizzare questa trasformazione energetica. Di tali convertitori di energia ondosa ne esistono diverse classificazioni. Scopo di tale lavoro è analizzare l’efficienza di un nuovo convertitore di energia ondosa, chiamato WavePiston, al fine si stabilire la fattibilità di una sua reale applicazione in diverse condizioni ondose: dalle più energetiche del Mare del Nord, alle più quiete del Mar Mediterraneo. La valutazione sul WavePiston è basata sullo studio sperimentale condotto nell’Università di Aalborg, in Danimarca; e su di una modellazione numerica del dispositivo stesso, al fine di conoscerne l’efficienza a prescindere dalla possibilità di avere risultati di laboratorio. Il modello numerico è in grado di predirre le condizioni di laboratorio, ma non considera ancora elementi come gli ancoraggi o valutazione dei costi

Effects of Mooring Systems on the Performance of a Wave Activated Body Energy Converter

none3siAim of this paper is to analyse the power and hydraulic performance of a floating Wave Energy Converter with the purpose at optimising its design for installation in arrays. The paper presents new experiments carried out in 1:30 scale on a single device of the Wave Activated Body type in the deep-water wave tank at Aalborg University. Power production and wave transmission were examined by changing the mooring system, the wave attack and the device orientation with respect to the incoming waves.. To assure the best performance the device size may be “tuned” based on the local peak wave length and the mooring system should be selected to allow the device for large movements.mixedZanuttigh B.; Angelelli E.; Kofoed J. P.Zanuttigh B.; Angelelli E.; Kofoed J. P

Physical and numerical modelling of mooring forces and displacements of a Wave Activated Body Energy Converter

none4The paper analyses the forces on the mooring system and the device motions of a floating Wave Activated Body Energy Converter under ordinary and extreme wave conditions. The investigation has been carried out with physical and numerical approaches. The physical tests were performed in 1:60 scale in the shallow-water wave tank of Aalborg University, whereas the numerical simulations were performed in 1:1 scale with the AQWA code developed by ANSYS. The spread mooring system tested in the laboratory allowed for an efficient device keeping while minimising the space. The loads on the moorings increase with increasing the significant wave height and show a modest trend with the peak wave length. These experimental measurements were compared with the numerical results, suggesting that AQWA model is able to accurately reproduce the standard deviation of the forces on the mooring lines. From the simulations it is highlighted that the device should work far from resonance condition, because when the typical wave period is near to the natural period (in surge) the forces acting on the mooring lines increase, resulting in a high level of energy loss.noneElisa Angelelli; Barbara Zanuttigh; Luca Martinelli; Francesco FerriElisa, Angelelli; Zanuttigh, Barbara; Martinelli, Luca; Francesco, Ferr

A methodology for multi-criteria design of multi-use offshore platforms for marine renewable energy harvesting

Multi-use offshore platforms (MUPs) combining renewable energy from the sea, aquaculture and transportation facilities can be considered as a challenging way to boost blue growth and make renewable energy (especially wave energy) environmentally and socio-economically sustainable. MUPs allow sharing the financial and other market/non-market costs of installation and management, locally using the produced energy for different functionalities and optimizing marine spatial planning. The design of these solutions is a complex interdisciplinary challenge, involving scientists and technical experts with different backgrounds. This paper presents a new methodology for the design of a MUP based on technical, environmental, social and economic criteria. The methodology consists of four steps: a pre-screening phase, to assess the feasibility of different maritime uses at the site; a preliminary design of the alternative schemes based on the identified maritime uses; a ranking phase, where the performance of the MUPs is scored by means of expert judgment of the selected criteria; a preliminary design of the selected MUP selected. An example application of this procedure to a site offshore the Western Sardinia coast, Mediterranean Sea, Italy, is provided. In this site the deployment of a MUP consisting of wave energy converters, offshore wind turbines and aquaculture is specifically investigated

Binding of gaseous Fe(III)-heme cation to model biological molecules: Direct association and ligand transfer reactions

The binding of a variety of ligands with Fe(III)-heme(+)ion, prosthetic group of heme proteins, has been studied in the gas phase by ESI-FT-TCR mass spectrometry. The ligands have been selected among substrate molecules of heme proteins (e.g., NO, nitroso compounds) or among model compounds acting for the functional groups that are present in the protein backbone (e.g., amines, thioethers, nitriles, ketones, amides, etc.). Both the kinetic and the thermodynamic features of the addition reactions are reported. Fe(III)-heme(+) ions react faster with]one pair donor ligands as the reaction becomes increasingly thermodynamically favored (higher heme cation basicity of the ligand, HCB, namely -Delta G degrees for the ligand addition reaction). In turn HCBs correlate in general with the gas phase basicity toward the proton of the various ligands. A ligand addition equilibrium is established with weaker ligands, methanol, acetonitrile and acetone, yielding absolute HCB values, whereas ligand transfer equilibriums allowed a scale of relative (and absolute) HCBs to be constructed. NO displays exceptional binding properties towards Fe(III)-heme(+), unrelated to the low gas phase basicity toward the proton of this molecule, which is clearly the basis for the paramount role of heme proteins in NO binding and regulation. (J Am Soc Mass Spectrom 2005,16,589-598) (c) 2005 American Society for Mass Spectrometr