• Energy Research
• 2021-2025close

E-Motions is a low-cost and versatile/adaptable wave energy converter conceived towards harnessing energy from wave/wind-induced roll oscillations of floating platforms. This paper focuses on a recently conducted parametric physical modelling stage with three hull designs (half-cylinder, half-sphere and trapezoidal prism), which features a disruptive Power Take-Off reproduction. Free decay, inclining and free-fall tests denoted a good agreement between the physical model's properties and the estimates. Parametric regular waves tests yielded data regarding reflection and transmission coefficients, while large peak-to-peak roll amplitudes (nearly 80) were measured for the half-cylinder and, to a lesser extent, the half-sphere. Peak reduction was observed under resonant conditions, with the introduction of the Power Take-Off, to which adds a motion phase difference between it and the floating platform. On power output, the half-cylinder and half-sphere yielded the highest capture width ratios and power values per metre of device (nearly 0.8 kW/m, in prototype values) and per displaced volume (up to 0.08 kW/m3). Albeit sufficient for supporting some marine activities, these values can be bolstered, in the future, either through alternative mass/damping combinations or stacking various rows of generators. Maximum mean-to-max power ratios reached a value of 11, within the standard literature range, from literature.

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.

Seaports are at the forefront of global trade networks, serving as hubs for maritime logistics and the transportation of goods and people. To meet the requirements of such networks, seaport authorities are investing in advanced technologies to enhance the efficiency and reliability of port infrastructures. This can be achieved through the digitalization and automation of core systems, aimed at optimizing the management and handling of both goods and people. Furthermore, a significant effort is being made towards a green energy transition at seaports, which can be supported through marine renewable sources. This promotes energy-mix diversification and autonomy, whilst reducing the noteworthy environmental footprint of seaport activities. By analyzing these pertinent topics under the scope of a review of container-terminal case studies, and these ports’ respective contexts, this paper seeks to identify pioneering smart seaports in the fields of automation, real-time management, connectivity and accessibility control. To foster the sustainable development of seaports, from an energy perspective, the potential integration with marine renewable-energy systems is considered, as well as their capabilities for meeting, even if only partially, the energy demands of seaports. By combining these fields, we attempt to construct a holistic proposal for a “model port” representing the expected evolution towards the seaports of the future.

This paper seeks to identify promising sites and technologies, in Portugal, for co-located wave energy conversion and offshore aquaculture, whilst providing benchmark implementation references and guidelines to researchers. Accordingly, two case study sites are considered for deployment of five wave energy devices and up to six aquaculture species. A thorough analysis in terms of power ratios, efficiency, redundancy, species viability, device survivability and costs is performed, seeking to find viable co-located solutions. It is found that the Wave Dragon device yields the most promising energy demand coverage and energy output (5 226 to 6 817 MWh/ year). Nevertheless, it may require rescaling towards optimal operation, while the OCECO 4 excels in terms of capacity factor (0.24-0.29) and default adaptation to the deployment sites. The WaveRoller (R) has the lowest single-unit cost (125 euro/MWh) but requires up to nine units to cover all the energy demand targets. Larger wave farms are required for the BBDB and AquaBuOY, albeit with potentially greater economies of scale and single-unit redundancy. These sites also enable cultivation of most of the considered species, even under ideal condi-tions. Lastly, it is recommended that the devices enter survivability mode at a significant wave height threshold of 5.5 m.

The wave energy sector has not reached a sufficient level of maturity for commercial competitiveness, thus requiring further efforts towards optimizing existing technologies and making wave energy a viable alternative to bolster energy mixes. Usually, these efforts are supported by physical and numerical modelling of complex physical phenomena, which require extensive resources and time to obtain reliable, yet limited results. To complement these approaches, artificial-intelligence-based techniques (AI) are gaining increasing interest, given their computational speed and capability of searching large solution spaces and/or identifying key study patterns. Under this scope, this paper presents a comprehensive review on the use of computational systems and AI-based techniques to wave climate and energy resource studies. The paper reviews different optimization methods, analyses their application to extreme events and examines their use in wave propagation and forecasting, which are pivotal towards ensuring survivability and assessing the local wave operational conditions, respectively. The use of AI has shown promising results in improving the efficiency, accuracy and reliability of wave predictions and can enable a more thorough and automated sweep of alternative design solutions, within a more reasonable timeframe and at a lower computational cost. However, the particularities of each case study still limit generalizations, although some application patterns have been identified—such as the frequent use of neural networks.

Abstract Within the scope of a changing energy market, wave energy has yet to reach a level of commercial viability that enables it to become competitive with alternative energy sources, both renewable and non-renewable. Despite the well-known advantages inherent to the resource, there are several challenges that must be overcome before wave energy gains a relevant share of the global energy market. While near-commercial stages of development are still outside the reach of most wave energy converters, it is important to find new perspectives that facilitate the development process and improve the chances of a successful deployment and operation. In this paper, a review of synergetic technologies with the potential for hybridization and/or co-location with wave energy converters is presented. Potential applications of wave energy conversion devices, within the context of nearshore and offshore niche markets that minimize/eliminate, respectively, mainland grid connection and inherent costs are also discussed. It is found that mutual gains can be attained from this complementary approach, namely in terms of infrastructure sharing, critical component protection, introduction of a beneficial shielding effect, energy storage upgrading, coastal erosion mitigation and electricity supply to various marine mobile platforms for different offshore and nearshore activities, amongst others.

Seaports’ breakwaters serve as important infrastructures capable of sheltering ships, facilities, and harbour personnel from severe wave climate. Given their exposure to ocean waves and port authorities’ increasing awareness towards sustainability, it is important to develop and assess wave energy conversion technologies suitable of being integrated into seaport breakwaters. To fulfil this goal whilst ensuring adequate sheltering conditions, this paper describes the performance and stability analysis of the armour layer and toe berm of a 1/50 geometric scale model of the north breakwater extension project, intended for the Port of Leixões, with an integrated hybrid wave energy converter. This novel hybrid concept combines an oscillating water column and an overtopping device. The breakwater was also studied without the hybrid wave energy device as to enable a thorough comparison between both solutions regarding structural stability, safety, and overtopping performance. The results point towards a considerable reduction in the overtopping volumes through the integration of the hybrid technology by an average value of 50%, while the stability analysis suggests that the toe berm of the breakwater is not significantly affected by the hybrid device, leading to acceptable safety levels. Even so, some block displacements were observed, and the attained stability numbers were slightly above the recommended thresholds from the literature. It is also shown that traditional damage assessment parameters should be applied with care when non-conventional structures are analysed, such as rubble-mound breakwaters with integrated wave energy converters.