Developments of energy in EU–unlocking the wave energy potential

The New Entrance Reserve (NER300) is one of the leading mechanisms used for the application and promotion of clean energy projects. In this context, this study aims to investigate the evolution of wave energy projects within the first and second call of NER300. Furthermore, the study tries to identify the reasons of successful applications through an estimation analysis of energy production, avoided emission and energy security. Milder resources contain ‘hidden’ opportunities for wave energy, with lower expenditure and capacity factors equivalent and even over 20%. Lower extreme events indicate that associated installation costs can be considered reduced, thus the potential cost of energy may act as a positive driver for future development. The results of the study argue that there are regions with ‘hidden’ opportunities that can accelerate proof-of-concept and enhance viability for wave energy.Accepted Author ManuscriptTransport Engineering and Logistic

Selection index for Wave Energy Deployments (SIWED): A near-deterministic index for wave energy converters

This study introduces a novel index that accounts for the interactions of wave climate and wave energy converters, offering an unbiased approach that considers climate variability, survivability and energy production. Application of the index is done with use of a longterm wave hindcast validated database for the North Sea. A detailed overall and monthly wave resource assessment reveals that mean expected wave resource is ≈15 kW/m, with higher nearshore values in December-January ≈20-25 kW/m. Lower magnitudes are met in July with values closer to ≈ 4-6 kW/m, as a general observation higher resource magnitude is expected at upper parts of the North Sea, with diminishing levels towards the English channel, the difference in available resource is almost half. The region favours "smaller" capacity devices, with energy production, with capacity factors having encouraging results. The highest mean value for a capacity factor in the region is 25-32%. However, the new index indicated that the highest capacity factor value should not be the determinant parameter. In fact, other locations have less energy production per year, but with significantly less production pattern variation and lower extreme condition probabilities.Transport Engineering and Logistic

Energy and socio-economic benefits from the development of wave energy in Greece

The study quantifies socio-economic benefits by the integration of wave energy in Greece, through resource examination, availability and deployment considerations. Greece has a large number of inhabited islands that mostly utilise conventional fuels for power generation, inclusion of wave energy will contribute both in terms of energy independence but also in job creation. The Greek region is often overlooked, due to its lower resources, but through proper converter selection energy benefits can be significant. Furthermore, milder resources offer opportunities for capital expenditure reductions, hence reducing cost of device and energy. Scenarios consider technological maturity, legislation, and resource potential to quantify future cumulative installations that can be developed. If a wave energy converter (WEC) is selected properly, accounting for climate variability and persistence, an off-the-shelve WEC can operate at capacity factors starting from 20%. Based on a resource and availability assessment, the learning rates from an incremental approach are more suitable and allow cost reductions. Job creation targets island regions where majority of exploitable resource is located and can provide up to 1400 direct jobs. Adaptation of wave energy by Greece has the potential to offer major technological, energy and employment benefits.Transport Engineering and Logistic

Shifting wave energy perceptions: the case for Wave Energy Converter (WEC) feasibility at milder resources

Wave energy can provide significant benefits as renewables acquire more share in electricity production. So far, focus for the development of wave energy is given to areas with resources ≥ 25 kW/m, with moderate resources often not considered. Furthermore, waves have larger uncertainties associated with diverse portfolio of converters leading to higher Levelized Cost of Electricity (LCoE). This study challenges the notion of economic viability for moderate resources, therefore the methodology and results of this analysis are globally applicable. Several different types of wave converters suggest multi-zonal applicability, underlying the dependence on the diverse wave energy resource that can be harvested. It is clear that different zones favour alternative converters, common characteristic is that all have nominal capacity below 1 MW. Optimally selected converters, attain capacity factors over 30%, with LCoE depending more on discount rate-capital pairs, mean LCoE values are from 150 to 250/MWh with lowest value 60 €/MWh. Investment amortisation also depends on resource and LCoE pairs with an offshore wave farm able to retrieve its capital in 3.8 years (optimal case), 10 years (average). Projects with ≥3 Million €/MW and a higher risk discount of 10% are viable only for high performing devices with capacity factors ≥40%.Offshore EngineeringEnergy & Industr

Impacts of physical calibration of a spectral wave model and effects of using different temporal wind inputs

Spectral wave modelling can reduce uncertainties in the estimation of wave energy resource assessment, converter design, extreme value analysis, etc. In spectral models, wave growth is represented with different approaches, resulting in wave resource assessments having large differences especially at high wave values. In this paper a modified version of the North Sea Wave Database is used to quantify the impact of wind temporal fidelity on the wind growth components. The Simulating WAves Nearshore (SWAN) model has been modified, with two different wind inputs used from the European Centre for Medium-Range Weather Forecasts (ECMWF). Results are compared with in-situ measurements an inter-comparison for 20 years (1980-1999). Differences are found on mean and maxima values of wave parameters, with little changes in directionality. However, higher temporal resolution of the wind does not mean always a better hindcast, in fact attention to the calibration of wind-wave growth interactions and whitecaps leads to similar results. Finally, the high fidelity hindcasts are compared, identifying limitations and opportunities for improvements in wave energy assessments.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Offshore Engineerin

Levelised Cost of Electricity for wave energy converters and the perception of milder resource non-viability in the North Sea

Wave energy is one of the most dense, predictable, and persistent energy sources, that has gone under-utilised, with many countries exposed to it. Depending on orientation with regards of coastal fronts to swells, resources can be characterised as high, moderate, and low. Wave energy can provide significant benefits as renewables acquire more share in the electricity production. So far focus for the development of wave energy is given to areas with resources over 25 kW/m, with moderate resources often not considered. Furthermore, waves have larger uncertainties associated with diverse portfolio of converters leading to higher Levelized Cost of Electricity (LCoE). This study explores whether mild resource can be cost-effectively exploited, by properly attributing a “production-to-resource” approach. The main question answered is whether mild resources are viable for wave energy. This premise is often dismissed, without much consideration or evidenced arguments. In terms of wave energy production potential, the wave density potential (kW/m) is not the determining factor. Results aim to realistically assess the potential and alter the perception of non-viability for wave energy converters. Our study examines the evolution of LCoE at various locations in the North Sea and also tries to assess different impacts of external factors at the financial viability of wave energy farms.Offshore EngineeringEnergy & Industr

Change of nearshore extreme wind and wave climate in southeast Africa

L'uso eccessivo di combustibili fossili sta causando la riduzione delle riserve di carbone, oltre ad un aumento delle emissioni di gas “effetto serra” esacerbando i cambiamenti climatici. Tali condizioni alterano la circolazione dei venti sugli oceani e, di conseguenza, il clima ondoso, con effetti non solo sui regimi medi, ma anche sugli eventi estremi, la cui determinazione risulta di fondamentale importanza per una accurata gestione delle coste e per la riduzione del rischio costiero. L'Oceano Indiano è interessato da intensi cicloni tropicali sia nella zona settentrionale che meridionale (Gray, 1985; DuBe et alii, 1977) ed in quest'ultimo si registrano eventi estremi soprattutto nelle stagioni di dicembre-gennaio-febbraio (DJF) e marzo-aprile-maggio (MAM). Tuttavia, non è ancora chiaro come nelle aree costiere dell'Oceano Indiano meridionale i cicloni tropicali possano evolvere e quale sia l'impatto di tali alterazioni sul regime dei venti e sul clima ondoso. Nel presente studio, sono stati valutati gli eventi estremi sulle aree costiere dell'Africa sud-orientale considerando le proiezioni future secondo uno scenario RCP (Rappresentative Concentration Pathway) 8.5 della quinta fase del modello CMIP5 (Coupled Model Inter-comparative Project). L'analisi è stata effettuata sulla base della variazione stagionale degli eventi estremi sotto costa, al fine di determinare le variazioni nel breve e nel lungo periodo. I risultati indicano che la maggior parte delle aree vicino alla costa africana nel nord e nel sud del Canale del Mozambico, a est e sud-ovest del Madagascar e le coste di Reunion e Mauritius sono soggette ad eventi estremi specialmente durante le stagioni DJF e MAM. Le proiezioni dei cambiamenti del clima meteomarino mostrano una maggiore intensità degli eventi estremi sotto costa quasi in tutte le stagioni. I risultati (Tabella 1) indicano, inoltre, che i valori massimi di velocità del vento nelle aree costiere dell'Africa sud-orientale aumenteranno dell'1% e del 16% nei mesi di settembre-ottobre-novembre (SON) e giugno-luglio-agosto (JJA), mentre durante le stagioni dei cicloni tropicali (DJF e MAM), aumenteranno, rispettivamente, dell'11% e del 4%. Di conseguenza, le altezze significative delle onde estreme aumenteranno in media del 10% durante DJF, JJA e SON. Durante i mesi MAM, nonostante le previsioni mostrino un incremento degli eventi estremi al largo dell'Oceano Indiano meridionale, si osserva una riduzione dell'intensità degli eventi estremi sotto costa, a causa del cambiamento delle traiettorie dei tifoni. Climate change impact assessment is vital in order to investigate not only the change of average wind and wave climate, but also the extreme events. Such kind of events can affect the activities in nearshore areas such as marine operation, as well as on design of coastal and marine structures. In this research, longterm assessment of wind and wave data has been conducted to determine the effect of climate change by comparing the dataset for historical and future projections. The analysis has been done mainly in nearshore areas and the results were discussed in order to evaluate the impact of climate change, quantitatively.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic

Wind effects in the parametrisation of physical characteristics for a nearshore wave model

To properly assess the energy and waves at a region, it is vital to obtain suitable long term metocean conditions. Although, wave buoys are a significant source of information they are not able to provide a detailed and complete resource assessment, as they have inherent spatiotemporal and recording limitations. Therefore, numerical wave models are often used to estimate wave power and metocean conditions. A wave model can provide realistic representation of physical processes, but it should entail careful tuning of parameters, which are often based on empirical and semi-empirical configurations. The study presents calibration of a wave numerical model and examines its performance, for nearshore wave assessments. Parametrisations of wind growth and whitecappingcoefficients have direct effects on evolution of locally generated waves, swells, and can reduce uncertainty in the results of a hindcast. The results are used to explain the physical meaning of differences, and provide a detail comparison of metocean parameters with nearshore and shallow water buoys as in-situ benchmarkers. Inter-model comparisons also indicate differences in spatial wave generation and propagation, as affected by wind growth and dissipation rates. The “optimal” solution will result in a model that will be used to provide a long-term high resolution metocean and wave power assessment for the Netherlands, that so far has been lacking in wave energy resource characterisation.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic

North Sea Wave Database ( NSWD ) and the need for reliable resource data: A 38 year database for metocean and wave energy assessments

The study presents a newly generated hindcast database of metocean conditions for the region of the North Sea by parametrising the newly introduced ST6 physics in a nearshore wave model. Exploring and assessing the intricacies in wave generation are vital to produce a reliable hindcast. The new parametrisations perform better, though they have a higher number of tuneable options. Parametrisation of the white capping coefficient within the ST6 package improved performance with significant differences 20–30 cm. The configuration which was selected to build the database shows a good correlation 95% for Hm0, has an overall minimal bias with the majority of locations being slightly over-estimated 0.5–1 cm. The calibrated model was subsequently used to produce a database for 38 years, analysing and discussing the metocean condition. In terms of wave energy resource, the North Sea has not received attention due to its perceived ``lower'' resource. However, from analysing the long-term climatic data, it is evident that the level of metocean conditions, and subsequently wave power, can prove beneficial for development. The 95th percentile indicates that the majority of the time Hm0 should be expected at 3.4–5 m, and the wave energy period Te at 5–7 s. Wave power resource exceeds 15 kW/m at locations very close to the coast, and it is uniformly reduced as we move to the Southern parts, near the English Channel, with values there being 5 kW/m, with most energetic seas originating from the North East. Results by the analysis show that in the North Sea, conditions are moderate to high, and the wave energy resource, which has been previously overlooked, is high and easily accessible due to the low distance from coasts. The study developed a regional high-fidelity model, analysed metocean parameters and properly assessed the energy content. Although, the database and its results can have multiple usages and benefit other sectors that want to operate in the harsh waters of the North Sea.Transport Engineering and Logistic

Performance Modelling Of Flap-Type Wave Energy Converter Array: Flaps With Various Dynamic Characteristics

Generally, it is expected that the total power of N energy converters in an array will be less than N times the power of a single operative converter. The goal of this paper is to enhance the oscillation of the flap-type WEC and consequently the energy extraction of the whole array in front of a coastal structure. Flaps in an array show different response patterns in terms of amplitude and frequency based on their dynamic characteristics, incoming wave frequencies, and the distance between the WECs. Through this work, different dynamic characteristics for each flap in combination with various distances between proximate flaps are investigated. An experimentally validated numerical model developed for the simulation of flap-type WEC operating as single and in an array is used for the simulation. The effects of dynamic characteristics and WEC distances on the response and power production are estimated and discussed in detail for a flap operating in an array of two and five. It is shown that by changing the distance between two flaps, the response is enhanced up to 20%. The findings suggest the most efficient ratio of dynamic characteristics of flaps in an array of two is having a period half to the incoming wave period. However, for an array of five, having staggered flaps with a period equal to the incoming wave period make a 4% increase in the overall response of each flap.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Offshore Engineerin