Search Results (108)

Ocean energy is an abundant, eco-friendly, and renewable energy resource that is useful for powering sensor networks connected to the maritime Internet of Things (MIoT). These sensor networks can be used to measure different marine environmental parameters that affect ocean infrastructure integrity and harm marine ecosystems. This ocean energy can be harnessed through hybrid nanogenerators that combine triboelectric nanogenerators, electromagnetic generators, piezoelectric nanogenerators, and pyroelectric generators. These nanogenerators have advantages such as high-power density, robust design, easy operating principle, and cost-effective fabrication. However, the performance of these nanogenerators can be affected by the wear of their main components, reduction of wave frequency and amplitude, extreme corrosion, and sea storms. To address these challenges, future research on hybrid nanogenerators must improve their mechanical strength, including materials and packages with anti-corrosion coatings. Herein, we present recent advances in the performance of different hybrid nanogenerators to harvest ocean energy, including various transduction mechanisms. Furthermore, this review reports potential applications of hybrid nanogenerators to power devices in marine infrastructure or serve as self-powered MIoT monitoring sensor networks. This review discusses key challenges that must be addressed to achieve the commercial success of these nanogenerators, regarding design strategies with advanced simulation models or digital twins. Also, these strategies must incorporate new materials that improve the performance, reliability, and integration of future nanogenerator array systems. Thus, optimized hybrid nanogenerators can represent a promising technology for ocean energy harvesting with application in the maritime industry. Full article

Waves generated by the wind in oceans and seas have a significant available quantity of clean and renewable energy. However, harvesting their energy is still a challenge. The integration of an oscillating water column (OWC) wave energy converter into a breakwater leads to more viability, since it allows working as both harbor and coastal protection and harvesting wave energy. The main objective of this study is to investigate different configurations of L-shaped duct OWC devices inserted into vertical and sloped (2:3) impermeable breakwaters for different lengths of the lip by using a numerical model based on the Reynolds-Averaged Navier-Stokes equations. The ANSYS FLUENT^® software (2016) is used in 2D numerical simulations by adopting the volume of fluid method to consider the two-phase free surface flow (water and air). It was observed that both the length of the lip and the length of the L-shaped duct OWC significantly influence the resonance and the efficiency of the OWC device. In addition, the performance of the OWC device varies significantly with its geometric configuration, which needs to be adapted for the local sea state. Full article

Wave energy, as a vast renewable resource, remains underutilized despite its high potential. The oscillating water column (OWC) is one of the most efficient way to harvest wave energy. Due to the randomness of ocean wave excitation, a control strategy is needed to keep the conversion efficiency of OWC at a certain level. In this paper, an adaptive model predictive control (AMPC) method is proposed to optimize the efficiency of the air turbine and improve the overall efficiency of the OWC. Experiments were conducted in a wave flume to obtain realistic wave data, which were fed into the AMPC model for simulations. Results indicate that AMPC-optimized turbine efficiency exhibits improved performance under regular wave conditions and significantly enhances efficiency within certain intervals under short-period irregular waves. However, as the wave period increases, optimization becomes less stable. Overall, the study concludes that the adaptive MPC model effectively optimizes turbine efficiency under most conditions, highlighting its potential for enhancing OWC performance. Full article

With the increasing global emphasis on sustainable energy, wave energy has gained recognition as a significant renewable marine resource, drawing substantial research attention. However, the efficient conversion of low-frequency, random, and low-energy wave motion into electrical power remains a considerable challenge. In this study, an advanced hybrid generator design is introduced which enhances wave energy harvesting by optimizing wave–body coupling characteristics and incorporating both a triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) within the shell. The optimized asymmetric trapezoidal shell (ATS) improves output frequency and energy harvesting efficiency in marine environments. Experimental findings under simulated water wave excitation indicate that the accelerations in the x, y, and z directions for the ATS are 1.9 m·s⁻², 0.5 m·s⁻², and 1.4 m·s⁻², respectively, representing 1.2, 5.5, and 2.3 times those observed in the cubic shell. Under real ocean conditions, a single TENG unit embedded in the ATS achieves a maximum transferred charge of 1.54 μC, a short-circuit current of 103 μA, and an open-circuit voltage of 363 V, surpassing the cubic shell by factors of 1.21, 1.24, and 2.13, respectively. These performance metrics closely align with those obtained under six-degree-of-freedom platform oscillation (0.4 Hz, swing angle range of ±6°), exceeding the results observed in laboratory-simulated waves. Notably, the most probable output frequency of the ATS along the x-axis reaches 0.94 Hz in ocean trials, which is 1.94 times the significant wave frequency of ambient sea waves. The integrated hybrid generator efficiently captures low-quality wave energy to power water quality sensors in marine environments. This study highlights the potential of combining synergistic geometric shell design and generator integration to achieve high-performance wave energy harvesting through improved wave–body coupling. Full article

Today, there is a marked increase in interest in the share of renewable energy sources in the energy mix, which benefits the environment. This also applies to the energy of sea (wave) current, as, without a doubt, the offshore area is becoming one of the leading areas of renewable energy, which translates into changes in energy production. This can be exemplified by the latest research in the context of theory, design, modeling, as well as application, control, and monitoring of wave turbines to enhance their performance. This article reviews the research in this context, systematizes information, identifies literature gaps, and presents future directions in this area. For this purpose, 3240 English-language publications from 2015 to 2024 were identified in the Scopus database. The data are analyzed according to the selected research domains. Some of them are review or conceptual in nature, while others are empirical in nature (experimental attempts and case studies). From this point of view, it becomes possible not only to systematize the state-of-the-art but also to identify future research prospects. Full article

The Peruvian coast covers more than 3000 km along the Pacific Ocean, being one of the richest seas in terms of biodiversity, productivity, fishing, and renewable energy potential. Marine renewable energy (MRE) in both offshore and coastal environments of Peru is, currently, a huge reserve of practically unused renewable energy, with inexhaustible potential. In this context, renewable energies from hydroelectric, biomass, wind, and solar sources have been applied in the country, but geothermal, waves, tidal currents, and tidal range sources are currently underdeveloped. This article presents the enormous source of sustainable blue energy for generating electrical energy that exists in Peru from waves and tidal resource potential. In addition, this article presents the main opportunities, gaps, and key issues for the implementation of marine renewable energy (MRE), with emphasis on: (i) showing the available potential in the northern, central, and southern Pacific Ocean territories of Peru, (ii) characterizing the marine energy best available technologies to implement, (iii) the environmental and socio-economic impacts of marine renewable energy, and (iv) discussion of challenges, opportunities, and future directions for developments in the marine energy sector. Finally, the article concludes that the greatest possibilities for exploiting the abundant marine renewable energy (MRE) resource in Peru are large spaces in both offshore and coastal environments on the Pacific Ocean that can be considered for harvesting energy. These issues will depend strongly on the implementation of regulations and policies for the strategic use for planning of marine resources, encouraging research and development (R&D) for creating sustainable innovations, incentives for project finance mechanisms, and developing specialized local human capital, considering the sustainability of livelihoods of coastal communities and ecosystems. Full article

Wave energy is one of the most reliable and promising renewable energy sources that has attracted lots of attention, including piezoelectric wave energy harvesting devices. One of the challenges for piezoelectric wave power generation is the relatively low-frequency wave environments in the ocean. Magnetic excitations are one of the techniques used to overcome this issue. However, there is a lack of understanding of the mechanisms to maximize the electric power output of piezoelectric wave energy harvesters through magnetic excitations. In the present study, magnetic excitation experiments were conducted to investigate the power generation of a coupled spring pendulum piezoelectric energy harvester under various magnetic field conditions. Firstly, the mass of the load magnet that can induce the resonance phenomenon in piezoelectric elements was experimentally determined. Then, the power generation of piezoelectric elements was tested under different excitation magnetic spacings. Finally, the influence of different distribution patterns of excitation magnets on the performance of piezoelectric elements was tested. It was found that under the conditions of a load magnet mass of 2 g, excitation magnet spacing of 4 mm, and two excitation magnets stacked on the inner pendulum, optimum power generation of the piezoelectric wave harvester was achieved with a peak-to-peak output voltage of 39 V. The outcome of this study provides new insight for magnetic excitation devices for piezoelectric wave energy harvesting to increase the feasibility and efficiency of wave energy conversion to electrical energy. Full article

Ocean energy, e.g., waves, tidal current, and thermal and salinity gradient, can be used to produce electricity. These marine-based renewable energy technologies are at relatively early stages of development and potentially deployed at various sea conditions. In the past, numerous studies were undertaken to explore the feasibility of harvesting of the marine energy in Malaysia; however, those studies were limited to a specific location (i.e., the east coast of Peninsular Malaysia and East Malaysia) and the consideration of sea level rise effect was not studied. This study assessed the potential of tidal and wave energy resources in Malaysia’s waters with the effect of projected sea level rise and was undertaken through numerical modeling using MIKE 21 software. The research outcomes were tidal and wave energy contours for Malaysia’s waters with an inclusion of the sea level rise projection for 2060 and 2100, as well as a potential site determined for tidal and wave energy harvesting. The simulation results highlight the significant potential of tidal and wave energy in specific locations around Malaysia and its coastal regions, as well as in the South China Sea’s offshore regions. By incorporating sea level rise projections into tidal and wave simulations, we revealed a notable increase in tidal and wave power. Full article

Energy harvesting from natural sources, including bodily movements, vehicle engine vibrations, and ocean waves, poses challenges due to the broad range of frequency bands involved. Piezoelectric materials are frequently used in energy harvesters, although their effectiveness depends on aligning the device’s natural frequency with the frequency of the target energy source. This study models energy harvesters customized for specific applications by adjusting their natural frequencies to match the required bandwidth. We evaluate commercially available piezoelectric transducers and model them using COMSOL Multiphysics alongside an equivalent spring-mass schematic approach, enabling precise adjustments to optimize energy capture. The proposed system achieves a maximum power output of 160 µW and a power density of 187.35 µW/${\mathrm{cm}}^3$ at a natural frequency of 65 Hz. Furthermore, the theoretical maximum power density is calculated as 692.97 W/${\mathrm{m}}^3$, demonstrating the system’s potential for high energy efficiency under optimal conditions. Simulations are validated against experimental data to ensure accuracy. Our findings provide a design framework for optimizing energy harvester performance across diverse energy sources, leading to more efficient and application-specific devices for varied environmental conditions. Full article

Magnetohydrodynamic (MHD) generators are direct energy conversion devices that transform the motion of an electrically conducting fluid into electricity through interaction with a magnetic field. Developed as an alternative to conventional turbine-generator systems, MHD generators evolved through the 20th century from large units, which are intended to transform thermal energy into electricity using plasma as a working fluid, to smaller units that can harness heat from a variety of sources. In the last few decades, an effort has been made to develop energy conversion systems that incorporate MHD generators to harvest renewable sources such as solar and ocean energy, strengthening the sustainability of this technology. This review briefly synthesizes the main steps in the evolution of MHD technology for electricity generation, starting by outlining its physical principles and the proposals to convert thermal energy into electricity, either using a high-temperature plasma as a working fluid or a liquid metal in a one- or two-phase flow at lower temperatures. The use of wave energy in the form of acoustic waves, which were obtained from the conversion of thermal energy through thermoacoustic devices coupled to liquid metal and plasma MHD generators, as well as alternatives for the transformation of environmental energy resources employing MHD transducers, is also assessed. Finally, proposals for the conversion of ocean energy, mainly in the form of waves and tides, into electric energy, through MHD generators using either seawater or liquid metal as working fluids, are presented along with some of the challenges of MHD conversion technology. Full article

This work embarks on an exploration of piezoelectric energy harvesting (PEH), seeking to unravel its potential and practicality. PEH has emerged as a promising technology in the field of civil engineering, offering a sustainable approach to generating energy from ambient mechanical vibrations. We will explore the applications and advancements of PEH within the realm of civil engineering, focusing on publications, especially from the years 2020 to 2024. The purpose of this study is to thoroughly examine the potential and practicality of PEH in civil engineering applications. It delves into the fundamental principles of energy conversion and explores its use in various areas, such as roadways, railways, bridges, buildings, ocean wave-based energy harvesting, structural health monitoring, and even extraterrestrial settings. Despite the potential benefits of PEH in these domains, there are significant challenges that need to be addressed. These challenges include inefficient energy conversion, limitations in scalability, concerns regarding durability, and issues with integration. This review article aims to address these existing challenges and the research gap in the piezoelectric field. Full article

Marine wave energy exhibits significant potential as a renewable resource due to its substantial energy storage capacity and high energy density. However, conventional wave power generation technologies often suffer from drawbacks such as high maintenance costs, cumbersome structures, and suboptimal conversion efficiencies, thereby limiting their potential. The wave power generation technologies based on micro-energy technology have emerged as promising new approaches in recent years, owing to their inherent advantages of cost-effectiveness, simplistic structure, and ease of manufacturing. This paper provides a comprehensive overview of the current research status in wave energy harvesting through micro-energy technologies, including detailed descriptions of piezoelectric nanogenerators, electromagnetic generators, triboelectric nanogenerators, dielectric elastomer generators, hydrovoltaic generators, and hybrid nanogenerators. Finally, we provide a comprehensive overview of the prevailing issues and challenges associated with these technologies, while also offering insights into the future development trajectory of wave energy harvesting technology. Full article

Renewable energy is the best choice for clean and sustainable energy development. A single renewable energy system reveals an intermittent disadvantage during the energy production process due to the effects of weather, season, day/night, and working environment. A generally hybrid renewable energy system (HRES) is an energy production scheme that is built based on a combination of two or more single renewable energy sources (such as solar energy, wind power, hydropower, thermal energy, and ocean energy) to produce electrical energy for energy consumption, energy storage, or a power transmission line. HRESs feature the outstanding characteristics of enhancing energy conversion efficiency and reducing fluctuations during the energy production process. Triboelectric nanogenerator (TENG) technology transduces wasted mechanical energies into electrical energy. The TENG can harvest renewable energy sources (such as wind, water flow, and ocean energy) into electricity with a sustainable working ability that can be integrated into an HRES for high power efficiency in sustainable renewable energy production. This article reviews the recent techniques and methods using HRESs and triboelectric nanogenerators (TENGs) in advanced hybrid renewable energy systems for improvements in the efficiency of harvesting energy, sustainable energy production, and practical applications. The paper mentions the benefits, challenges, and specific solutions related to the development and utilization of HRESs. The results show that the TENG is a highly potential power source for harvesting energy, renewable energy integration, application, and sustainable energy development. The results are a useful reference source for developing HRES models for practical applications and robust development in the near future. Full article

A flapping foil, which mimics the flapping wings of birds and the locomotion of aquatic organisms, is an alternative to a conventional turbine for the harvesting of renewable energy from ubiquitous flows in the atmosphere, oceans, and rivers. In this work, the energy harvesting performance of flapping foils with attached flaps at the trailing edge is numerically studied by using an immersed boundary–lattice Boltzmann method (IB-LBM) at a Reynolds number of 1100. Three different configurations are considered, namely, a clean NACA0015 foil, a NACA0015 foil with a single flap, and a NACA0015 foil with two symmetric flaps. The results show that the flap attached to the trailing edge is able to enhance the energy harvesting efficiency, and the two symmetric flaps can achieve more enhancements than its single-flap counterpart. The mechanism of such enhancements is attributed the separation of the interactions of vortexes generated at the upper and bottom surfaces of the foil. To further obtain the optimal configurations of the two symmetric flaps, the angle between the two flaps ($\alpha$) and the length ($l_f$) of the flap are systematically studied. The results show that the optimal energy harvesting performance is achieved at $\alpha ={60}^{\circ }$ and $l_f=0.1c$ (c denotes the chord length of the foil). Compared with the baseline case, namely, the clean NACA foil, the optimal configuration can achieve an improvement of efficiency up to 19.94%. This study presents a strategy by adding two symmetric flaps at the trailing edge of the foil to enhance the energy harvesting performance of a flapping foil, which contributes to advancing the development of simple and efficient clean energy harvesting by using a flapping foil. Full article

The primary goal of this study is to develop and test a small-scale horizontal-axis underwater Ocean Current Turbine (OCT) by creating a mathematical model for coupled dynamics aided by a Blade Element Momentum (BEM) simulation-integrated experimental approach. This research is motivated by the urgent need for sustainable energy sources and the vast potential of ocean currents. By integrating mathematical modeling with the experimental testing of scaled model OCTs, this study aims to evaluate performance accurately. The experimental setup involves encapsulating a 3D-printed turbine model within a watertight nacelle which is equipped with sensors for comprehensive data recording during towing tank tests. Through these experiments, we seek to establish correlations between the generated power, force, and rotational speed of the turbine’s Permanent Magnet DC (PMDC) motor, which determines the turbine’s capability to extract dynamic energy inflow. Moreover, this research aims to provide valuable insights into the accuracy and applicability of theoretical predictions in real-world scenarios by comparing the experimental results with BEM simulations. This combined approach not only advances our understanding of hydrokinetic energy conversion, but also contributes to the development of reliable and efficient renewable energy technologies that address global energy challenges while mitigating environmental impacts. Full article