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The aim of this paper is to report on a possible correlation between the Lévy index for wind velocity and the mean Energy Density of sea surface waves in the same location. The result is based on data obtained from 6 buoys located around the coast of Ireland and maintained by the Marine Institute of Ireland and a further 144 buoys located at variou...

## Contexts in source publication

**Context 1**

... energy and power densities of a wave are proportional to the square of the wave amplitude and knowledge of the average wave height is therefore important when considering where to place a wave farm. Figure 2 shows an average wave height map of the world where it is clear that the northern hemisphere (i.e. the northern Atlantic and Pacifc oceans) have the largest average wave heights. Further, in terms of the propensity of these waves to coast lines, there are two principal regions that stand out: (i) the Aleutian Islands; (ii) the west coasts of Ireland and Scotland. ...

**Context 2**

... this does not effect the statistical characteristics of the data, and, in each case, the data is seen to be Rayleigh-type distributed as illustrated in Figure 19 which shows 100-bin histograms of the signals given in Figure 18. Figure 20 shows plots of the Energy Density, the Power Density and the Energy Flux computed from equations (1), (2) and (3), respectively, using the samples of data from the M1 buoy shown in Figure 18. Note that all three signals have similar time signatures, and, apart from scaling, their statistical characteristics are similar. ...

**Context 3**

... of the goodness-of-fit associated with probability plots show that the data conform best to a Rayleigh distribution (compared with the normal, lognormal, exponential, extreme value and the Weibull family of distributions). This is demonstrated in Figure 22 which shows that both the energy density and Lévy index appear to be Rayleigh distributed accept at the extrema. Interestingly, the Lévy index is better Rayleigh distributed than the energy density. ...

**Context 4**

... Rayleigh distributed characteristics of the energy density is to be expected as it maps to the distribution of wave heights which, for a linear wave model, are Rayleigh distributed (see Figure 19). The deviation of data points from this distribution (as shown in Figure 22) is a possible reflection of non-linearities which are known to occur from time to time in sea surface waves especially with regard to deep water ocean waves and can lead to the generation of 'Freak Waves' (see [28] and references therein). However, application of the Wilcoxen Signed Rank Test (which removes information on the shape of the distribution given that Ranks are resistant to outliers) yields a 'p-value' of 1.1442 × 10 −21 and validity of the Null Hypothesis in this case (i.e. that the population medians are equal or the difference in population medians is zero) can be taken to be false. ...

**Context 5**

... although the energy density and Lévy index appear to conform to the same distributions, they are from 'different populations' and therefore independent. This is reflected in the scatter-plot given in Figure 23 which shows no clear correlation between parameters plotted. Thus, in the following section, we consider a new relationship between these parameters which is based on an analysis of the linear wave model compounded in equation (4) and (6). ...

**Context 6**

... c and m are arbitrary (real) constants. Figure 24 shows a plot of the data (samples of which are given in Tables I and II) and a linear fit to the data based on equation (9) where (working to 4 decimal places) m = −0.42699 and c = 1.0236 (the norm of residuals being 3.5562). ...

**Context 7**

... CONCLUSIONS AND FUTURE WORK The results given in Figure 23 are an indication of the possible validity of the scaling given by equation (9). The results provide the potential for developing a computational procedure to predict the mean Energy Density of a sea surface from data obtained on the wind velocity alone. ...

**Context 8**

... the EWEA vision becomes a realisation, the added concentration of HVDC terminals, offshore wind farms and increased grid interconnection will help drive forward the competitiveness of wave energy as they will be able to exploit the infras- tructure of wind farms in what are otherwise no-go marine areas. (Figure 25). We conclude this paper with the following points: ...

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... XVI. mendean, Errenazimenduaren garaitik, itsas animalien forma emulatuz gorputz fuselatu edo aerodinamikoen bidez mugimenduaren erresistentzia murrizteari buruzko lehen azterlanak identifikatzen dira (Leonardo da Vincik eginak) [3]. Itsas teknologiaren berrikuntzaren eta itsas animalien munduaren portaeraren arteko lotura horrek jarraitutasuna izan du ordutik hainbat alorretan, hala nola sentsore-sistemetan (eko-kokapena eta elektro-harrera), presioa eta flotagarritasuna kontrolatzeko mekanismoetan, energia-kontsumoa murrizteko estrategietan (diseinu fusiformea), egituren diseinuan edo egonkortasun-eta maniobra-mekanismoetan. ...

LABURPEnA: Natura inspirazio-iturri gisa aztertzeak itsasotik datorren energiaz ba-liatzeko makinak diseinatzea eragin du. Dokumentu honek biomimesian oinarrituriko itsas gailuak aztertzen ditu, haien portaeraren ondorioz energia bereganatzea errazten duten horietan oinarrituz [1]. Azkenik, marrazoen larruazala jariakinaren muga-geruza apurtzea ahalbidetzen duten espikula txikiz osatuta dagoenez, haren mugimenduare-kiko erresistentzia murriztuz [2], eta fenomeno horretan oinarrituz, olatuak sortzeko erabiltzen diren olatu-kanaletan (waveflumes) energia xahutzeko sistemetan aztertzen den aplikazioa zehaztuko da. HITZ GAkoAk: muga-geruza, itsas energiak, espikula dermikoak, olatu-kanala. AbstrAct: The study of nature as a source of inspiration has resulted in the design of different energy harnessing devices from the sea. This article brings together the marine devices based on biomimicry, focusing on those whose behavior favors the energy capture [1]. Finally, as the skin of sharks is formed by tiny spicules that allow breaking the boundary layer of the fluid and, thus, reducing the resistance to advance of the shark [2], the application under study in wave flume energy absorption systems will be detailed, which are laboratory devices that allow wave generation phenomena to be reproduced at reduced scale.

... Working principle of Archimedes Wave Swing[76]. ...

The proposal of new technologies capable of producing electrical energy from renewable sources has driven research into seas and oceans. Research finds this field very promising in the future of renewable energies, especially in areas where there are specific climatic and morphological characteristics to exploit large amounts of energy from the sea. In general, this kind of energy is referred to as six energy resources: waves, tidal range, tidal current, ocean current, ocean thermal energy conversion, and saline gradient. This review has the aim to list several wave-energy converter power plants and to analyze their years of operation. In this way, a focus is created to understand how many wave-energy converter plants work on average and whether it is indeed an established technology.

... (h, i) Attenuator devices, (h) Pelamis converter deployed in Spain and decommissioned in 2016 with a power installed capacity of 2.25MW, (i) McCabe Wave Pump with a power capacity installed of 1.59 MW and decommissioned in 1996[200][201][202]; (j, k) OWC devices, (j) OWEL converter deployed offshore in 2016 with a power installed capacity of 12MW, (k) SPAR converter deployed in Portugal and Spain coasts[ 65 , 203 , 204 ] and (l, m) Point Absorbers devices, (l) WaveBob converter deployed in Galway Bay (Ireland) in 1999 and later decommissioned, (m) AquaBuoy converter commercialized in Canada and Ireland with a power installed capacity of 2.5MW[ 66 , 192 , 205 ]. ...

The increase of energy demand in the past 50 years and the targets to reach net-zero carbon dioxide emissions have led to an increase of electricity production from renewable energy sources. This paper first gives a snapshot of the word's energy mix and then reviews the most widely used renewable energy sources in the market; comparing their reliability, efficiency and cost-effectiveness, and highlighting their major advantages and weaknesses. The review concludes that marine energy, and specifically wave energy, can be the emerging energy source capable of addressing many of the problems that current renewable energy concepts and devices present, although major challenges remain.
The paper is focused on the current global position of wave energy technologies in the market and under development in the past two decades, by looking at their status, reliability, energy generated, capacity installed and geographical locations. The current marine energy status of the main players, including France and South Korea, is compared with the rest of Europe and the wave energy status in Europe has been reviewed with an special interest in UK, as one of the major players, and Australia as a new emerging area of development. The main Wave Energy Converters (WECs) together with the world's wave energy density map were also discussed. This has led to a conclusion, that even though there is high energy potential, the wave technologies developed to date cannot offer a much needed breakthrough. A new concept of WEC based on a system of synchronized rotational pendula, having potential to work across-scales is introduced, which can motivate future work.

... Thus, understanding the temporal and spatial variations of the wind force regulated through different angles of incidence upon the sea surface is a fundamental issue. Another issue is the characteristic spectrum over which the wind force is converted into wave motion (Blackledge et al., 2013). Absence of systematic wave measurements for the Sea of Marmara causes a rather low reliability in coastal related studies. ...

The Sea of Marmara, a relatively small basin located between the Black Sea and the Aegean Sea with narrow seaways of the Bosphorus and the Dardanelles, has vital importance in coastal and ocean engineering activities due to substantial industrial development surrounding it and related sea traffic. Despite this importance, measurements concerning coastal engineering applications, in particular the wave climate, are quite scarce. Lack of essential data impairs the reliability of engineering works such as breakwaters and coastal protection structure designs. For a period of approximately one year between February 2013 and January 2014 Turkish Petroleum International Company (TPIC) carried out wave and wind measurements in the Sea of Marmara. The data were collected in 30-minute intervals throughout the one year span at the location of 41o04' N and 28o19' E with 50 m water depth. The present work analyses this rather unique data statistically for wind, wave height and energy conditions in the Sea of Marmara.

... For this reason, linear switched reluctance actuator structures can be a suitable option as generation devices. Ocean wave energy assessment plays an important role in the design of power take-off units for wave energy converters and can be estimated through statical analysis of measured ocean wave parameters [3] or trough prediction models based on wind velocity data [4]. Point absorber wave energy converters are characterized for low speed operations induced by the ocean surface waves. ...

In this work, 4 structural configurations are proposed, and analysed, to be used as a tubular linear switched reluctance generators with tubular topology (TLSRG). For the 4 models under assessment, inductance change with the mover part position is assessed to quantify the machine capabilities as generator for an wave energy converter (WEC), namely a point absorber device. This evaluation is supported by a 2D FEM analysis based software through which are determined the inductance values at different alignment conditions as well as the magnetic flux densities for the referred alignment conditions. An analytic design procedure is presented for one structural model and the same procedure is used to size the generator for given nominal power and based velocity, derived from an ocean wave energy assessment based on meteorological data.

... Thus, understanding the temporal and spatial variations of the wind force regulated through different angles of incidence upon the sea surface is a fundamental issue. Another issue is the characteristic spectrum over which the wind force is converted into wave motion (Blackledge et al., 2013). Absence of systematic wave measurements for the Sea of Marmara causes a rather low reliability in coastal related studies. ...

In this study, the wave energy potential of the Marmara Sea is computed using the 3rd generation Spectral Wave Model of DHI MIKE 21. European Center for Medium-Range Weather Forecasts (ECMWF) wind data is extracted and inserted into the model for the year 2012 to determine the wave properties. Observed wave data for two months in Ambarlı station is used for model calibration. The previous study was employed for comparison, which calculated wave properties of Marmara Sea for the period between the years 1998 and 2008. This study is developed to improve the previous work by two cases: (i) A new and finer mesh is generated. (ii) Our model results are compared with previous study in order to predict wave parameters for 2012. In comparison, the proposed model outperformed the previous study.

... Thus, understanding the temporal and spatial variations of the wind force regulated through different angles of incidence upon the sea surface is a fundamental issue. Another issue is the characteristic spectrum over which the wind force is converted into wave motion (Blackledge et al., 2013). Absence of systematic wave measurements for the Sea of Marmara causes a rather low reliability in coastal related studies. ...

In this study, the wave energy potential of the Marmara Sea is computed using the 3rd generation Spectral Wave Model of DHI MIKE 21. European Center for Medium-Range Weather Forecasts (ECMWF) wind data is extracted and inserted into the model for the year 2012 to determine the wave properties. Observed wave data for two months in Ambarlı station is used for model calibration. The previous study was employed for comparison, which calculated wave properties of Marmara Sea for the period between the years 1998 and 2008. This study is developed to improve the previous work by two cases: (i) A new and finer mesh is generated. (ii) Our model results are compared with previous study in order to predict wave parameters for 2012. In comparison, the proposed model outperformed the previous study.

For an efficient wave energy extraction, the evolution of some specific parameters must be known. These parameters, like significant wave height and period, are mainly determined by the wind speed and influenced by some sea environment characteristics. Their evolution in time is one of the basic information necessary for designing of an accurate energy conversion system. In many scientific works the benefits of artificial neural networks based modeling are presented. These models allow the prediction and optimization of the wave parameters starting from experimentally acquired data. Due to specific calculus method of the artificial neural networks, in order to obtain accurate results, a very important step is the appropriate neural model design. If the model is optimal correlated with the data processed, the results obtained can be more significant than those coming from the mathematical formulas. The main neural models parameters that must be taken into account for an optimal design are model structure, transfer function and training algorithm. This paper presents an investigation of the results obtained with different models, proving that for a specific dataset a specific neural model offers the best results. Several models are analyzed, for a dataset corresponding to specific point in Black Sea and a comparison of results is presented.