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Hydraulic experiments using physical scale models of monopile scour protections typically have high ex-perimental uncertainties and data scattering. These uncertainties may severely affect the accuracy of the experimental results and need to be analysed quantitatively. This paper presents a study on the quantification of experimental uncertainties in monopile scour protection damage tests following the Guide to the expression of Uncertainty in Measurement (GUM) (ISO, 2008). The uncertainty analysis is performed using the three-dimensional damage number S3D and the widely applied STAB number. Through the analysis of the S3D number from individual test and repeated tests, it is found that the uncertainty analysis method for an individual test can be efficiently applied to predict the experimental uncertainty. The wave peak period and the current velocity are identified as the two major sources of uncertainties for the S3D number. The flow turbulence and correlations between input parameters can be neglected when estimating the uncertainty. The uncertainty analysis of the STAB number shows that the experimental uncertainty due to measurement can be up to 5% to 7% of the obtained STAB result. This uncertainty range is wide in comparison with the narrow margin of a dynamic scour protection design in DNV's recent recommended practice (DNV-RP-0618). The uncertainty of the STAB number is more affected by the armour stone density, wave peak period and significant wave height.

Abstract E-Motions wave energy converter is a promising device capable of harnessing energy from wave/wind induced roll oscillations onto a generic floating platform, whose development was initiated with an experimental proof-of-concept study that, despite demonstrating the potentialities of the device, also highlighted the need for further developments, aimed at improving its performance and efficiency. This justified a new phase of numerical modelling, where E-Motions was reproduced within the ANSYS® AQWA™ environment, a potential theory-based numerical model widely used in the field of wave energy converter development. The model was setup (first stage) and calibrated (second stage) with experimental data from a proof-of-concept study, carried out on a 1:40 geometric scale, with a good agreement being obtained for the hydrostatic properties (difference below 5%) and hydrodynamic roll response (minimum average error of 2.83°). From a follow-up third stage, focused on comparing eight different hull solutions with similar natural roll periods, it was determined that the half-sphere and trapezoidal prism geometries produced the highest power outputs for the studied conditions (maximum average outputs of nearly 5 kW/m and 8 kW/m, respectively). These two designs were then adapted to a 1:20 geometric scale alongside an updated version of the half-cylinder, which served as a “control” case, and subjected to a final stage of numerical modelling centered on assessing the Power Take-Off’s influence (namely through variable damping and mass) in their performance. Outcomes from this stage denote the necessity of a careful selection of Power Take-Off mass/damping combinations, as a disproportionate relationship could lead to scenarios where the conversion system would stall on one of the superstructure’s sides, moving within a very limited range of the available sliding amplitude. Maximum average power output values reach nearly 24 kW, 30 kW and 18 kW for the half-cylinder, half-sphere and trapezoidal prism, respectively, with a follow-up experimental study being planned for the near future, in order to evaluate the validity of these results.

Abstract This work investigates the performance of CECO, a third-generation wave energy converter of the oscillating bodies group. The power matrices of the device – which represent the wave power absorbed for different sea states – are obtained for five PTO inclinations. Then, the wave climate along the west coast of the Iberian Peninsula is characterized by means of the wave energy resource matrices. With the power matrices and the wave energy resource matrices, the performance of the device along the area of study is determined for each PTO inclination. To achieve this, the performance of CECO is assessed by means of a panel model based on the boundary element method, while the wave conditions in the area of study are assessed with a wave propagation spectral model. The results allow fulfilling an important knowledge gap concerning the impact of the PTO inclination on the performance of CECO, which was found to be very significant. In addition, the insight obtained will contribute to optimize future versions of CECO and other wave energy converters of the oscillating body type.

Abstract This work aims to get a better insight into the behaviour of CECO, an oscillating-body wave energy converter that presents a singular feature: the motion of its oscillating part is restricted to translations along an inclined axis. In order to study in the time domain the response of CECO for a wide range of wave conditions, a hybrid numerical approach based on the Boundary Element Method (BEM) and the Morison’s equation was used. The effects of the power take-off system were included in the numerical model and calibrated with the results from previous wave basin experiments. The results show that CECO is able to capture up to 40% of the incident wave energy when the direction of translation is 45°. However, if the direction of translation is vertical, the amount of captured wave energy decreases almost three times. This investigation demonstrates the advantage of limiting the oscillation of the CECO floating part to an inclined direction and reaffirms the concept as a promising technology for wave energy conversion.

Abstract The Sea-wave Slot-cone Generator (SSG) is a multi-level overtopping based wave energy converter that can be installed either nearshore or offshore. The installation in harbor breakwaters and in the shoreline presents several advantages despite the usual exposure to smaller waves than at offshore locations. This work analyzes the effect of wave focusing walls ( i.e ., wave concentrators) on the performance of isolated SSG units using a physical model built on a geometric scale of 1/40. Seven configurations were defined by changing the opening angle and the crest level of those elements. The use of wave concentrators proved to be advantageous since a wider wave front is captured and the run-up and overtopping phenomena are enhanced on the SSG ramp owing to the wave energy concentration (walls tapering effect). In fact, the total mean power captured increased for all SSG configurations with concentrators in comparison to the base configuration (without concentrators), regardless of the sea state considered. In terms of hydraulic performance, the gain associated to the use of wave concentrators depends on the characteristics of incident waves, being higher for the smaller significant wave heights and the shorter peak wave periods. The hydraulic efficiency, defined as the ratio between the total mean power captured per meter of SSG width and the wave power per meter width of the incident waves, increases with the significant wave height and reduces with the peak wave period in all tested SSG configurations. In addition, in comparison to the base configuration, the hydraulic efficiencies with concentrators were higher for the smaller significant wave heights, but smaller for the other sea conditions. The use of wave concentrators increased the annual energy production approximately to the double. Overall, the application of the SSG technology in breakwaters presents itself as promising considering the characteristics of the wave resource nearshore or even in onshore locations.

Abstract Inspired by observing the motions of vessels at sea, the E-Motions has been proposed as an innovative concept capable of converting wave (and wind) induced roll oscillations on multipurpose offshore floating platforms into electricity. The device can be integrated, theoretically, into any type of offshore floating structure, given its simple 3-component design: floating platform, encasing and sliding Power Take-Off. This latter component can be sheltered from the marine environment by being placed within a casing, at deck level, or the hull of the offshore structure. With so much potential for application at sea, it was important to subject the E-Motions to an initial proof-of-concept, as done for other wave energy converters. This paper presents and discusses the main results and conclusions of an experimental study, carried out with a 1:40 reduced scale physical model, aimed at demonstrating the technical and technological viability of the E-Motions. It was found that, for the considered study variables, the device can operate without major incident and convert electricity from wave induced roll oscillations. Four ballast configurations were considered, of which two yielded higher power outputs. The average measured power reached as high as 11 kW and 13 kW, respectively, with the values reducing for wave period further away from the resonance range and lower wave heights. Power Take-Off damping was found to be an important variable that can considerably influence the energy generation process, yet it will be imperative to further assess this variable in combination with other pertinent variables, such as an external attached mass and different generators. This is key to better understand and describe the complex and non-linear relationship between the motions of the Power Take-Off and the floating platform components.

Abstract CECO is a recently proposed Wave Energy Converter (WEC), which harnesses both the kinetic and potential energy of waves. Currently, CECO is at the third level of technology readiness (TRL3). In this context, maximising the wave energy absorption under a wide range of wave conditions is crucial for the future development of the device. Therefore, this work aims to explore in detail the main parameters (operating water depth and wave conditions) that influence CECO's performance in terms of Captured Energy ( C E ) and Captured Energy Efficiency ( C E E f f ). For this purpose, a panel-based model, which was calibrated from previous physical model tests was used to construct the CECO matrices of absorbed wave power at different operating water depths. The wave conditions of the Atlantic coast of the Iberian Peninsula (2005–2014), which were modelled using SWAN, were used as case study. Overall, CECO offers promising results for C E and C E E f f , reaching values up to 600 M W h and 45%, respectively. In addition, it was found that CECO's power absorption reaches its maximum for values of peak wave periods ( T p ) ranging from 10 to 13 s and the fact that the operating water depth does not impact significantly the performance of the device.

Abstract Several eco-labels for wild-caught seafood have been developed during the last decade. This article describes and analyses the criteria applied by four different eco-labelling schemes for seafood products from capture fisheries, and discusses the criteria in terms of environmental impacts, based on the ISO 14040 standard for life cycle assessment. It is concluded that the most widespread eco-label, the Marine Stewardship Council (MSC), mainly addresses the fishing stage, in particular the overexploitation of marine resources. LCA studies confirm that the fishing stage represents the most significant environmental burden, but energy consumption and emissions of anti-fouling agents at the fishing or harvesting stage contribute with significant impacts that are not being addressed by international labelling initiatives for wild-caught seafood. LCA studies show that significant environmental impacts are related to the life cycle stages after landing. This includes fish processing, transport, cooling and packaging (especially for highly processed seafood products). Hence, another challenge would be to include criteria related to the post-landing consumption of energy, certain materials and chemicals, waste handling and wastewater emissions. Minimizing product losses throughout the product chain would also be an important area for future criteria in order to avoid fishing at high environmental costs only to produce something that is later wasted. The analysis shows that the Swedish KRAV is the only one that currently addresses a range of issues that include energy and chemicals in the whole life cycle of the products. International initiatives such as MSC cover fish products from many parts of the world emphasizing ‘overexploitation of fish resources’. It is recommended, however, that international initiatives such as MSC develop criteria related to energy use and chemicals – at least at the fishing stage. Over time, other life cycle stages could be addressed as well to the extent that this is manageable.

CECO is a novel Wave Energy Converter (WEC) concept, which has shown promising results in previous studies. The present work focuses on assessing the performance of CECO for a 11-year horizon in relation to the characteristics of the wave climate (intra and inter-annual seasonal variations) by means of two performance indicators defined ad hoc: Captured Energy (CE) and Captured Energy Efficiency (CEEff). For this purpose, the CECO matrix of absorbed wave power was constructed for an operating water depth of 30 m using the panel-based model ANSYS®-AQWA™. The Atlantic coast of the Iberian Peninsula, which presents a highly seasonal and energetic wave climate, was used as case study. Overall, it was found that CECO is able to capture large amounts of wave energy, especially for milder wave conditions, with values of CEEff exceeding 40%. However, for harsher wave conditions the results of CEEff decrease considerably ranging from 10% to 20%, which may result from the current design of CECO. In this context, the results obtained offer some valuable insight into the future evolution of CECO with the purpose of addressing the limitations of the current design and to optimise its performance according to the wave conditions for specific locations.