Showing papers on "Wave power published in 2022"

Recent Progress on Wave Energy Marine Buoys

Abstract: This study aims to introduce and discuss the recent research, development and application of wave energy marine buoys. The topic becomes increasingly appealing after the observation that wave energy technologies have been evolving in the recent decades, yet have not reached convergence. The power supply is usually the bottleneck for marine distributed systems such as buoys. Wave energy technologies are especially useful in this sense, as they can capture and convert the promising “native” renewable energy in the ocean (i.e., wave energy) into electricity. The paper enumerates the recent developments in wave energy capture (e.g., oscillating bodies) and power take-off (e.g., nanogenerators). The study also introduces the typical marine buoys and discusses the applicability of wave energy technologies on them. It is concluded that the wave energy technologies could be implemented as a critical addition to the comprehensive power solution of marine distributed systems. Wave energy buoys are likely to differentiate into “wave energy converter buoys” and “wave-energy-powered buoys”, which is indicated by the ratio of the generated power to the load power.

A heaving system with two separated oscillating water column units for wave energy conversion

Abstract: A theoretical model based on the linear potential theory is presented for two heaving oscillating water column (OWC) devices separated by a gap. The model includes relative motion and phase control between the devices and trapped water columns, and the hydrodynamic performance of the dual-OWC system thence evaluated. Matching conditions are employed along the common interfaces, and the power take-off model and motion equations of the OWC devices are incorporated into the solution procedure. At the top of each chamber, a Wells turbine is installed to extract wave power. To achieve the optimal overall power extraction performance, a numerical strategy of successive approximation is utilized to seek the optimal turbine damping combinations for the separated units. The effects of lip-wall draft and chamber breadth on the performance of a fully-free heaving dual-OWC system are explored. In view of the deficiency of a fully-free heaving system, two alternative optimization strategies are proposed, one focusing on the control of relative motion and phase between the water columns and the heaving devices, the other on utilizing resonance phenomenon inside the gap, achieved by tuning imposed linear spring constants and gap distance, respectively. It is shown that the control between heave motion of devices and water columns inside the chambers is beneficial for extracting more power over a broader range of wave frequencies. Moreover, enhanced extraction is likely over a wider range of wave conditions when the gap distance to wavelength triggers a sloshing mode inside the gap.

Wave energy converters in low energy seas: Current state and opportunities

Abstract: Existing wave energy technology has been designed for ocean waves, which, however, shorten the lifespan of wave energy converters and mooring systems. Furthermore, commissioning and maintenance in the harsh ocean conditions are challenging and expensive. For wave energy technology to realise its full potential and become commercially attractive, smaller, more economical, and resilient converters should be first introduced, tested, and optimized, as was the case with wind energy. Low energy seas such as the Mediterranean, Baltic, Caspian, Black, and Red Sea are ideal for this purpose. However, the body of knowledge on wave energy converters is limited and primarily focuses on the Mediterranean. Low capacity factors have been reported, which suggests that existing technology should be downscaled to fit the milder wave regimes. Climate change tends to increase the wave energy resource, which could be beneficial for wave energy harnessing, however, will greatly affect beach and coastal erosion and ports functionality. Converters in the nearshore can protect ports and the coast and mitigate erosion. Other secondary functions include desalination, hydrogen production, pumped-storage hydroelectricity, photovoltaic panel integration, and wave-wind farms co-location. Even though wave energy converters can counter beach erosion, they might also negatively affect aquatic ecosystems through vibrations and low-frequency long-duration noise, but little attention has been paid to their environmental impacts. Overall, wave energy can increase renewable energy penetration, decarbonize power generation, and promote job creation, and low energy seas can play an important role in advancing existing technology and help the industry progress.

A Review of Power Electronics for Nearshore Wave Energy Converter Applications

Abstract: In compliance with the green energy policy, mitigation from high fossil fuel dependency is becoming a new objective for most countries, including Malaysia. Wave energy is among extensively explored renewable energy relatively clean, sustainable, and inexhaustible resources. To this day, neither definite wave energy technology nor widely available commercial wave farm supplying the grid has existed. Therefore, wave energy harvesting is the most compelling solution, especially in regions where the possibility of grid connection is low in the nearest future. Like other renewable energy, the voltage amplitude and frequency generated from waves are unstable and may vary continuously. This uncertainty has created energy transfer challenges since the grid requires a stable and uninterrupted energy supply. Therefore, power electronics devices are employed to modulate the controller circuits’ pulse width. Further understanding of the relationship between wave energy conversion technology and its power conversion, particularly for nearshore applications, is summarized. This work also discussed selected wave energy conversion research and power conversion system implemented and studied in Malaysia. Finally, this review can provide extensive overview and broad understanding into power conversion system for Wave Energy Conversion, especially for nearshore applications.

Wave Energy Potential Analysis in the Casablanca-Mohammedia Coastal Area (Morocco)

Abstract: In the last two decades, the exploitation of marine renewable energies (70% of the globe is made up of oceans), especially wave energy, has attracted great interest, not only for their high potential, but also for their high energy density. The development of wave energy is suitable for countries or regions with extensive coastline and high waves approaching the shore. This paper focuses on the study of wave potential and wave energy distribution in the Casablanca-Mohammedia nearshore area (Moroccan Atlantic coast) in order to identify prospective wave energy hotspots. To achieve this purpose, the offshore wave potential was firstly estimated from a 20 years wave data provided by ECMWF (European Center for Medium range Weather Forecasts). In the second step, a numerical modeling of the wave propagation in the study area was performed using the SWAN model jointly with WAVEWATCHIII. The performance of the model to simulate accurately the wave field was evaluated in a real situation characterized by large waves. The model then was applied to determine the patterns of wave field in the Casablanca-Mohammedia nearshore area for a typical wave conditions (winter, summer and storm). The results of this study show the abundance of wave energy in the region with an average annual wave potential of about 22 kW/m. A seasonal variability of the wave resource was demonstrated, with values five times higher in winter than in summer. In addition, a major hotspot site was identified that should be considered when studying WEC implementation. This hotspot is located at the southern edge of the Casablanca-Mohammedia coast, near the coastal area of Sidi Rahal.

Powering data buoys using wave energy: a review of possibilities

Abstract: Abstract Data buoys are a widespread method of not only monitoring environmental parameters, but have a range of other applications: from surveillance to providing power for autonomous underwater vehicles (AUVs). The majority of data buoys currently in use are either solely powered by batteries, or they employ an array of solar panels to sporadically top up the battery power when environmental conditions are suitable. Less usual for data buoys is the use of wind power—though some successful hybrids of the two, such as the AXYS Technologies WindSentinel, also exist. As wave power technology matures, advancements in this currently underdeveloped technology could allow data buoys the option of using wave energy converters (WECs) as an alternative renewable power source. Data buoys could provide a small-scale application of WECs where many of the issues with harvesting such a stochastic and irregular energy source would be highlighted. The lessons learned in developing wave-powered data buoys could potentially be applied to larger, more costly wave energy applications such as wave farms or megawatt-level generators. This review considers data buoy projects currently in development—particularly those that look to incorporate a wave energy harvesting mechanism as either their primary or secondary power source, and their prospects, both as end-use applications in their own right, and as low-cost platforms to prove emerging wave energy technology for larger-scale use.

Linking the long-term variability in global wave energy to swell climate and redefining suitable coasts for energy exploitation

Abstract: The sustainability of wave energy linked to the intra- and inter-annual variability in wave climate is crucial in wave resource assessment. In this study, we quantify the dependency of stability of wave energy flux (power) on long-term variability of wind and wave climate to detect a relationship between them. We used six decades of re-analysis wind and simulated wave climate in the entire globe and using two 30-yearly periods, we showed that not only the previously suggested minimum period of 10 years for wave energy assessment appears to be insufficient for detecting the influence of climate variability, but also the selection period for wave energy assessment can lead to an over/underestimation of about 25% for wave power. In addition, we quantified the dependency of rates of change of wave power, wind speed and wave parameters and showed that the change in wave power is mainly a function of change in swell wave climate globally. Finally, we redefined the suitability of global hotspots for wave energy extraction using intra-annual fluctuation, long-term change, and the available wave power for the period of six decades. The results highlight the importance of climate variability in resource assessment, sustainability, and prioritizing the hotspots for future development.

Some Fundamental Results for Cyclorotor Wave Energy Converters for Optimum Power Capture

Abstract: Cyclorotor-based wave energy converters (WECs) present a relatively new and innovative paradigm for wave energy harvesting. Their operational principle is based on the generation of lift forces on the rotating hydrofoils due to their interaction with wave-induced circulation of water particles. As a result, relatively little is known about their optimal operation. To date, cyclorotor device performance has been measured by the power of waves radiated by the WEC, while a constant rotational velocity, consistent with the wave frequency, is employed. In this note we show (a) that variation of the cyclorotor velocity within the incoming monochromatic wave period significantly increases the generated mechanical power, while (b) optimising wave cancellation is at odds with the maximisation of shaft power. To optimise shaft power, the letter adopts a multi-harmonic solution for variable cyclorotor rotation rate, inspired by methods developed in other WEC domains.