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Review

The Energy Conversion and Coupling Technologies of Hybrid Wind–Wave Power Generation Systems: A Technological Review

by
Bohan Wang
1,
Zhiwei Sun
1,
Yuanyuan Zhao
1,
Zhiyan Li
1,
Bohai Zhang
1,
Jiken Xu
1,
Peng Qian
1,2,* and
Dahai Zhang
1,2,*
1
Ocean College, Zhejiang University, Zhoushan 316021, China
2
Hainan Institute of Zhejiang University, Sanya 572025, China
*
Authors to whom correspondence should be addressed.
Energies 2024, 17(8), 1853; https://doi.org/10.3390/en17081853
Submission received: 12 March 2024 / Revised: 11 April 2024 / Accepted: 11 April 2024 / Published: 12 April 2024
(This article belongs to the Section A: Sustainable Energy)
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Abstract

:
Based on the mutual compensation of offshore wind energy and wave energy, a hybrid wind–wave power generation system can provide a highly cost-effective solution to the increasing demands for offshore power. To provide comprehensive guidance for future research, this study reviews the energy conversion and coupling technologies of existing hybrid Wind–wave power generation systems which have not been reported in previous publications. The working principles of various wind and wave energy conversion technologies are summarised in detail. In addition, existing energy coupling technologies are specifically classified and described. All aforementioned technologies are comprehensively compared and discussed. Technological gaps are highlighted, and future development forecasts are proposed. It is found that the integration of hydraulic wind turbines and oscillating wave energy converters is the most promising choice for hybrid wind–wave power extraction. DC and hydraulic coupling are expected to become mainstream energy coupling schemes in the future. Currently, the main technological gaps include short their operating life, low energy production, limited economic viability, and the scarcity of theoretical research and experimental tests. The field offers significant opportunities for expansion and innovation.

1. Introduction

With the intensity of the energy crisis, the international structure of energy has gradually shifted from traditional fossil fuels to clean, renewable energy sources [1]. Ocean renewable energy sources, such as offshore wind, wave, and solar energies, are not only abundant but also widely distributed, garnering global attention [2,3]. Europe currently has the world’s largest installed ocean energy capacity, which is expected to increase to 188 GW by 2025 [4]. Countries such as the UK, Denmark, France, Germany, and Belgium have implemented lasting policies to promote the development of ocean renewable energy [5,6]. In alignment with this global trend, the Chinese government has committed to ocean energy development and its utilisation through significant national strategies, including the ‘12th Five-Year Plan’ in 2012 and the ‘13th Five-Year Plan’ in 2020. These strategic initiatives underscore the heightened focus on expanding China’s ocean energy capabilities and increasing its investment in renewable energy development [7].
Compared to other ocean energy sources, offshore wind energy is considered the most promising because of its high energy density and well-established technological development. One of the most famous demonstration projects of this is WindFloat Atlantic, which is located 20 km off the coast of Viana do Castelo, Portugal. It is considered to be the world’s first semi-submersible floating wind farm and was the first floating wind farm in continental Europe [8]. Ambitious plans have been formulated to increase wind farms’ capacity from 12 GW in 2020 to 300 GW by 2050 in the EU and from 5 GW in 2020 to 200 GW by 2050 in China [9,10]. However, the inherent randomness and intermittence of offshore wind energy inevitably lead to large power fluctuations in the terminal power system, resulting in increased maintenance and balance costs [11,12,13]. To address this challenge, various multi-energy complementary power generation schemes have been proposed that integrate offshore wind energy with other ocean energy sources [14,15,16,17,18,19]. Among these, the combined wave–wind power generation system is considered to be the best option due to its economic efficiency and technical feasibility [20,21,22,23].
Offshore wind and wave energies can compensate for each other in time and space, showing a certain synergy between the wave peaks that follow wind peaks [24,25]. The combined exploitation of offshore wind energy and wave energy has several advantages, including enhanced energy yields, improved predictability, smoothed output power, cost-effectiveness, and environmental benefits [26,27,28]. In recent years, numerous countries have conducted comprehensive resource assessments of offshore wind and wave energy to develop combined wind–wave power generation systems [29,30,31,32,33,34,35,36,37]. Based on their foundation and layout, combined wind–wave power generation systems can be classified as follows [26]: co-located (Figure 1a), island systems (Figure 1b), and hybrid systems (Figure 1c). Co-located systems and island systems consist of large offshore wind farms and wave energy converter arrays on independent foundations in the same marine area [38,39]. The major technologies of these systems are relatively mature and many demonstration projects have been implemented globally [40,41,42,43,44]. Hybrid systems, identified as a new research hotspot in recent years, combine offshore wind turbines and wave energy converters on the same foundation [45]. Compared with co-located and island systems, hybrid systems have the advantages of a smaller size, lower manufacturing and maintenance costs, and higher energy utilisation efficiency per unit area [46]. The most renowned hybrid wind–wave system is part of the WindFloat Atlantic project. This system has three floating wind turbines with a total capacity of 25 MW and a wave energy converter developed by the Portuguese company WavEC Offshore Renewables [47]. The wind turbines are anchored using advanced floating platforms that allow them to operate in deeper waters. The wave energy converter, which is integrated into the same floating platform as the wind turbine, captures energy from ocean waves.
Although hybrid wind–wave systems have recently become a research hotspot, studies on hybrid wind–wave systems are limited. The current research is primarily categorised into three groups: (i) potential assessments of hybrid wind–wave explorations [31,51,52,53,54]; (ii) hydrodynamic studies on substructures such as wave energy converters, wind turbines, and floating or bottom-fixed platforms [55,56,57,58,59,60,61,62]; and (iii) the power preferences of their integrated systems [63,64,65,66,67]. Several reviews have been conducted on these research areas in recent years. Qiang et al. assessed the potential of hybrid wind–wave exploration in Australia [31]. Iglesias et al. classified combined wind–wave systems and reviewed WEC technologies [26]. Hongda et al. provided a comprehensive review, which included global assessments of wind energy and wave energy resources and the foundation structures of hybrid wind–wave systems [45]. McTiernan and Sharman reviewed the types of hybrid wind–wave systems and discussed their advantages and disadvantages [68]. Subbulakshmi et al. summarised the state-of-the-art experimental and numerical methods used for the dynamic analysis of hybrid wind–wave systems [69]. Anthony et al. reviewed industrial projects for hybrid wind–wave energy extraction [70]. However, there are no publications that provide a systematic review of the energy conversion and coupling technologies of existing hybrid wind–wave systems.
The effectiveness of a hybrid wind–wave power generation system relies heavily on its seamless integration of energy conversion and coupling technologies. This paper presents a comprehensive review of the energy conversion and coupling technologies of existing hybrid wind–wave systems. A major contribution of this study is that it provides an in-depth analysis of the current state of the research in this field, emphasising the importance of efficient energy conversion and coupling strategies. The remainder of this paper is organised as follows: In Section 2, the energy conversion technologies of existing hybrid wind–wave systems are illustrated. Section 3 classifies and analyses the energy coupling technologies of existing hybrid wind–wave systems. Section 4 discusses these technologies, elaborates on technological gaps, and forecasts the development of these technologies. Finally, the conclusions are presented in Section 5.

2. Energy Conversion Technologies

The development of hybrid wind–wave systems has benefited significantly from the technological advancements in offshore wind turbines and wave energy converters. These systems combine offshore wind turbines and wave energy converters on the same foundation. This section presents a summary of the wind and wave energy conversion technologies utilised in existing hybrid wind–wave systems. The classification of these technologies is illustrated in Figure 2.

2.1. Wind Energy Conversion Technologies

Hybrid wind–wave systems utilise the same foundation structures as traditional offshore wind turbines, comprising both floating and bottom-fixed foundations. The wind energy conversion technologies employed in existing hybrid wind–wave systems can be divided into two types: mechanical–electrical and hydraulic–electrical.

2.1.1. Mechanical–Electrical Schemes

Mechanical–electrical wind energy conversion schemes are widely employed in hybrid wind–wave systems. Over the past decade, numerous demonstration projects have been conducted, such as Wave Treader [71], W2Power [72], Floating Power Plant AS [73], and WindWaveFloat [74]. In addition, a considerable number of conceptual hybrid wind–wave systems employing a mechanical–electrical wind energy conversion scheme have been proposed over the past three years [65,67,75,76,77]. A typical mechanical–electrical wind energy conversion scheme is depicted in Figure 3. The blades are driven by wind, and their pitch angles and rotational speeds are continually adjusted to optimise their wind energy utilisation efficiency. The generator converts wind energy into electrical energy.
There are two energy conversion processes in the mechanical–electrical wind energy conversion scheme. First, wind energy is converted into mechanical energy, and the generator transforms that mechanical energy into electrical energy. However, the generator’s output power is subject to instability due to the uncertainty and intermittency of wind. Consequently, additional energy storage and regulation components are necessary for wind turbine systems.

2.1.2. Mechanical–Hydraulic Schemes

Many researchers have integrated hydraulic transmission technology into offshore wind turbines to reduce system complexity and improve energy transmission efficiency. A typical mechanical–hydraulic wind energy conversion scheme is shown in Figure 4. These systems first convert wind energy into mechanical energy, and then convert that mechanical energy into hydraulic energy. Although mechanical–hydraulic wind energy conversion schemes have not been implemented in commercial hybrid wind–wave systems, they offer significant advantages such as stepless speed regulation, a high power-to-weight ratio, flexible transmission, and low maintenance costs [79,80]. In recent years, there has been a clear upward trend in the number of the studies focusing on these systems [81,82].

2.2. Wave Energy Conversion Technologies

Various wave energy converters have emerged worldwide over the past few decades and their performance has been systematically studied [83,84,85,86,87]. A comprehensive wave-to-wire model was developed to evaluate wave energy’s conversion from sea resources to the grid [88]. In hybrid wind–wave systems, wave energy converters are installed on the foundation of offshore wind turbines. Based on their working principles, the wave energy conversion technologies of hybrid wind–wave systems can be classified into three types: oscillating bodies, oscillating water columns, and overtopping.

2.2.1. Oscillating Bodies Systems

Oscillating bodies systems (OBs) are widely employed in existing hybrid wind–wave systems, as shown in Figure 5. Notable examples include Wave Star [58,89], Pelamis [90], and W2Power [72]. Many conceptual prototypes have been developed in recent years [91]. In hybrid wind–wave systems, OBs are installed on a floating or bottom-fixed platform to capture wave energy via the movements of various oscillating bodies [92]. The structures of OBs can be divided into oscillating bodies, Power Take-Off (PTO) systems, and generators. Oscillating bodies are excited by waves, which convert the wave energy into mechanical energy. The PTO system transmits the mechanical energy of the oscillating bodies to the generator.
There are two types of PTO systems in OBs: hydraulic and direct-drive PTO systems. The hydraulic PTO scheme is widely applied because of its high energy transmission efficiency, simple structure, and strong controllability [95]. A typical hydraulic wave energy PTO system, illustrated in Figure 6, consists of a hydraulic cylinder, hydraulic pipelines, hydraulic control and regulation components, and a hydraulic motor. A hydraulic cylinder can convert wave energy into hydraulic energy [96]. Hydraulic control and regulation components can reduce the pressure fluctuations across the entire system [97].
In recent years, several conceptual prototypes have been developed for direct-drive PTO systems [98,99,100,101]. Direct-drive PTO systems can be classified as mechanical-drive and electrical-drive, as illustrated in Figure 7. A mechanical-drive PTO system comprises various mechanical components that transmit the mechanical energy of the oscillating bodies to the generator shaft. This complex structure increases the energy loss and decreases the system’s life. In contrast, an electrical-drive PTO system consists of a linear generator and a simple mechanical structure. The oscillating body is excited by waves and drives the linear generator to generate electricity.

2.2.2. Oscillating Water Column Systems

Although OBs have been used in several commercial projects, the high damage rate of their mechanical components results in high maintenance costs [102,103,104]. Compared with other wave energy converters, oscillating water column devices (OWCs) are more suitable for integration into hybrid wind–wave systems. OWCs consist of a semi-submerged chamber and a turbo generator (Figure 8). OWCs have the advantages of a simple structure and long operating life [105,106]. The waves continually move up and down, compressing the air out of the chambers and then back into them through the turbo generator. The turbo generator is driven by airflow.
Based on this foundation, hybrid wind–wave systems utilising OWCs are primarily categorised into bottom-mounted and floating systems, as shown in Figure 9. In a bottom-mounted system, an offshore wind turbine is fixed to the seabed. The OWCs are installed onto the wind turbine tower. The floating-type system involves mounting both the offshore wind turbines and the OWCs on a shared floating platform [107].

2.2.3. Overtopping System

Existing research on overtopping wave energy converters is scarcer than that on OBs and OWCs. The number of hybrid wind–wave systems that employ overtopping wave energy converters is limited. The primary advantage of overtopping wave energy converters is their structural simplicity. A schematic drawing of an overtopping wave energy converter is shown in Figure 10. Waves run up along a ramp and flow into a reservoir installed at a level higher than the sea. The water drives a hydro-turbine connected to a generator via water flow [110].
At present, there are only a few studies on hybrid wind–wave systems that employ overtopping wave energy converters. The most well-known demonstrations are WPR and 2Wave1Wind, developed by OWWE [112]. Fiaschi et al. proposed an offshore multi-energy exploitation system with a yearly energy production potential of 177,000 kWh [113]. The overtopping wave energy converter used in this system was a Wave Dragon (Figure 11a). Moschos et al. designed a hybrid wind–wave system containing two offshore wind turbines and four overtopping wave energy converters (Figure 11b). The output power of this system was 2000 kW [40]. However, hybrid wind–wave systems employing overtopping wave energy converters have disadvantages, such as high construction and maintenance costs, low mobility, and intermittent power generation, which limit their application.

3. Energy Coupling Technologies

Currently, mainstream research on hybrid wind–wave systems focuses on their hydrodynamic performance and resource assessments. However, only a limited number of studies have been conducted on energy coupling technologies. This section summarises and analyses the energy coupling technologies of current hybrid wind–wave systems. The energy coupling subsystem used significantly influences the electric energy production of the entire system. According to their working principles, the energy coupling technologies used in existing hybrid wind–wave systems are classified as electrical or hydraulic coupling. These specific classifications are presented in Figure 12.

3.1. Electrical Coupling

Electrical coupling schemes utilise electrical components to integrate and regulate the power from both wind and wave sources. Electrical coupling schemes are widely applied in currently active hybrid wind–wave systems, such as Poseidon37, W2Power, WaveStar, and WaveTreader. Based on their type of coupled voltage, electrical coupling schemes can be further classified into AC and DC coupling schemes.

3.1.1. AC Coupling

AC coupling schemes offer the advantages of a simple structure and low costs. The configuration of an AC coupling scheme is shown in Figure 13. In this setup, AC/DC converters (rectifiers) are employed to convert the alternating currents generated by different generators into direct currents. These direct currents are then transformed into alternating currents of the same frequency using DC/AC converters (inverters). Finally, the alternating currents from different circuits are connected to the grid.
The back-to-back pulse-width modulation (PWM) converter is the primary variable-frequency controller in existing AC coupling schemes due to its strong controllability, reliability, and flexibility. A typical back-to-back PWM circuit is shown in Figure 14. Currently, the research on AC coupling schemes can be classified into two categories: one focuses on the topological optimisations of back-to-back PWM conversion circuits, while the other focuses on various control strategies.

AC Microgrid Technology

Microgrid technologies provide an efficient approach for enhancing system performance. Wang et al. presented a microgrid system aimed at achieving the hybrid extraction of offshore wind energy and wave energy. This system comprises a voltage source converter, high-voltage DC link, and damping controller [114]. Soundarya et al. designed a hybrid DC/AC microgrid to integrate captured offshore renewable energy and introduced a maximum power point tracking fuzzy control algorithm [115].

Novel Control Strategies

Novel control strategies have been proposed recently. The authors in [75] proposed a hybrid wind–wave system that applied an optimised intelligent neural network controller to enhance the dynamic performance of their system and maximise energy harvesting. The entire system was simulated and analysed using PSCAD/EMTDC V4 software. Qin et al. proposed an offshore hybrid power generation system using a coordinated control method [116]. This system uses grid voltage regulators and DC-link voltage regulators to control the system’s voltages. In [117], an innovative method was proposed to regulate the voltages and currents of a multiport magnetic bus, and a damping controller was designed to maximise wave energy harvesting.

3.1.2. DC Coupling

With the rapid development of power electronics, numerous innovative DC coupling systems have been integrated into hybrid wind–wave systems in recent years. The configuration of DC coupling schemes is shown in Figure 15. Initially, the alternating currents generated by the different generators are converted into direct currents by AC/DC converters. Subsequently, the direct currents are integrated. Finally, the coupled direct current is adjusted by the regulation components and converted back into an alternating current by the DC/AC converters.

DC Microgrid Technology

Compared with AC microgrids, DC microgrids are more flexible and reliable. Lu et al. proposed a hybrid wind–wave system with a DC microgrid that connected a wind turbine and a wave energy converter via AC/DC converters [64,118]. The entire system was modelled and simulated using MATLAB/Simulink, and its power performance under various operational conditions was analysed. Talaat et al. presented a multi-energy integrated system consisting of an AC/DC converter and a DC/DC converter [76]. The wind and wave energy conversion systems were integrated into a DC busbar, and a buck-boost circuit was designed to maintain a stable DC busbar voltage.

Novel Control Strategies

Additionally, several innovative approaches based on DC coupling circuits have been explored. Chen et al. combined a wind turbine with a direct-drive wave energy converter and designed a full-bridge controlled rectifier circuit to integrate wind and wave energies [66]. The authors of [100] proposed a hybrid wind–wave system capable of providing stable power to customers on remote islands. This system employed a doubly fed induction generator for wind energy capture and a linear permanent magnet generator for wave energy capture. Rasool et al. proposed a hybrid wind–wave system with a distribution network that employed back-to-back converters to maximise the energy extraction from wind and wave energy [101].

3.1.3. Energy Storage Technology

Energy storage technologies for electrical coupling systems can be divided into two types: batteries and mechanical storage. Battery storage systems typically use lithium-ion, lead-acid, or other types of batteries to chemically store electricity. When the electricity demand increases or decreases, the stored energy can be discharged from the batteries to supply power to the grid [119]. Mechanical storage elements store energy either mechanically or kinetically.
Zhang et al. proposed a hybrid wind–wave system with an integrated energy storage system [120]. In this system, the proposed integral compensation control method maximises energy capture and regulates the rotation speed of the wind turbine rotor. The alternating currents generated by the wind and wave energy conversion subsystems are integrated into the system bus after being regulated by back-to-back PWM converters and transformers. Liu et al. innovatively applied multitoothed doubly salient permanent magnet machines to serve different generators and used a battery tank to store excess energy [121]. Li et al. proposed a hybrid wind–wave system connected to a large power grid through a flywheel energy storage system [122]. They found that this flywheel energy storage system effectively stabilised power fluctuations. In another study [123], researchers proposed a novel hybrid wind–wave system comprising an offshore wind turbine and a point absorber with a hydraulic PTO system. The power sharing among different generators was governed based on their DC-link voltage, and two mechanical storage schemes were employed to smooth the DC voltage fluctuations at the DC coupling point.
Battery storage systems offer fast response times and can be easily scaled to meet various energy storage requirements. However, they have a limited energy capacity and lifespan, and there are concerns regarding the environmental impact of battery production and disposal [124]. Mechanical storage elements can provide larger energy storage capacities and longer lifespans but may have slower response times and higher upfront costs [122].

3.2. Hydraulic Coupling

In hydraulic coupling schemes, the energy from the wind and wave energy conversion subsystems is integrated and regulated using hydraulic components. The configuration of a hydraulic coupling scheme is shown in Figure 16. Although no commercial projects have employed hydraulic coupling schemes, existing studies have demonstrated their excellent power performance. Compared to electrical coupling, hydraulic coupling can reduce maintenance costs and enhance the system’s operating life due to its simplified structure. Based on the number of generators, hydraulic coupling schemes are further classified into multi-generator schemes and single-generator schemes.

3.2.1. Multi-Generator Schemes

A typical multi-generator scheme is shown in Figure 17. However, research on multi-generator schemes is limited. One notable engineering case is the W2P proposed by Chen et al., which comprises an offshore wind turbine and three oscillating body wave energy converters. This system demonstrated a wave energy conversion efficiency of over 80% [125]. In this system, the energy conversion subsystems convert wind and wave energies into hydraulic energy. Hydraulic oil from different hydraulic circuits is regulated and integrated by accumulators. Finally, the hydraulic motors connected to the generators are driven.

3.2.2. Single-Generator Schemes

A typical single-generator scheme is illustrated in Figure 18. There is only one generator in this energy coupling system. Compared with multi-generator schemes, single-generator schemes further simplify their system structure, resulting in a higher price performance ratio and longer operating life.
Shi et al. designed a hybrid wind–wave system with hydraulic transmission that consisted of an offshore wind turbine and two oscillating body wave energy converters [126]. The system was simulated using MATLAB/Simulink 2016 and AMESim 17.0 software. The results showed that the energy coupling efficiency of the system was maintained at 75%. Tri et al. proposed a hybrid wind–wave system containing a vertical-axis wind turbine and two wave buoys [127]. This system utilised a variable-inertia hydraulic flywheel to maximise its energy extraction from waves. However, this system lacks an effective control strategy; therefore, its overall efficiency is only 41.5%.
Zhejiang University (ZJU) proposed an on–off controlled hybrid wind–wave system that employs electromagnetic directional valves and pressure sensors to realise the energy coupling of different hydraulic circuits [128]. This scheme effectively reduces the negative coupling effect between two energy conversion subsystems. To minimise the energy losses resulting from interrupted flow rates, ZJU proposed a pressure-regulating hybrid wind–wave system utilising two additional hydraulic pumps to match the pressure levels [129]. Kong et al. proposed a hybrid wind–wave system with hydraulic transmission, which utilised an accumulator and a variable displacement pump for short-term energy storage [130]. Wang et al. proposed a novel hybrid wind–wave system with an adaptive motor speed control method [63]. The system was simulated using MATLAB/Simulink and AMESim 19.0 software. The simulation results indicated an average energy coupling efficiency of 89%.

4. Discussion

Representative hybrid wind–wave systems worldwide, established from 2010 to 2023, are listed in Table 1. Because studies on hybrid wind–wave systems are still at an early stage, discussions about their energy conversion and coupling technologies are crucial.

4.1. Wind Energy Conversion Technologies

Currently, mechanical–electrical wind energy conversion schemes account for a large proportion of wind energy conversion technologies. They have been applied in many demonstration projects, whereas mechanical–hydraulic wind energy conversion schemes are still in the conceptual stage or are under study in model experiments. The primary reason for this is that the relevant technologies for mechanical–electrical schemes are more mature than those for mechanical–hydraulic schemes. A detailed comparison between mechanical–electrical and mechanical–hydraulic schemes is presented in Table 2. The Levelized Cost of Energy (LCOE) is a standardized way to compare the economic competitiveness of different energy technologies [138]. After a comprehensive assessment, the LCOE of mechanical–hydraulic schemes was found to be higher than that of mechanical–electrical schemes. Although mechanical–hydraulic schemes have not yet reached full maturity, their significant advantages have been identified. Moreover, the number of studies on hydraulic wind turbines has rapidly increased in recent years. Therefore, mechanical–hydraulic wind energy conversion schemes have great potential to provide a cost-effective method to accelerate the development of hybrid wind–wave systems.

4.2. Wave Energy Conversion Technologies

A detailed comparison of the different wave energy conversion schemes is presented in Table 3. Overtopping systems are suitable for integration into existing structures but require a large reservoir volume. OWCs offer simplicity and versatility but are sensitive to wave conditions. OBs have the potential for higher efficiency but may be more complex. Compared with overtopping systems and OBs, OWCs have the most balanced LCOE in terms of cost and efficiency [142]. The use percentages of the different wave energy conversion schemes from 2012 to 2023 are shown in Figure 19a. OBs and OWCs are the most widely used in existing hybrid wind–wave systems, whereas overtopping schemes are scarce because of their high installation and maintenance costs. OBs are widely used due to their high efficiency. However, complex mechanical and hydraulic systems have increased initial capital and maintenance costs and reduced operational lifespans.
The number of studies on the hybrid wind–wave systems using OWCs has gradually increased in recent years. Among the various wave energy converters, the energy capture efficiencies of OWCs are relatively high [104,143]. OWCs can be installed on wind turbine towers, platform foundations, or floating platforms, exhibiting strong construction flexibility. In addition, OWCs exhibit a long operating life and strong adaptability to various operating conditions [144]. The combination of OWCs with offshore wind turbines for hybrid energy exploitation has attracted increasing attention worldwide.
Table 3. Comparison between different wave energy conversion schemes.
Table 3. Comparison between different wave energy conversion schemes.
SchemeAdvantagesDisadvantages
OBs
  • Can capture energy from a wide range of wave directions [86]
  • Higher efficiency compared to some other wave energy conversion systems [145]
  • Complex mechanical and hydraulic systems
  • High initial capital and maintenance costs [146]
OWCs
  • Simple design
  • Lower maintenance costs
  • Can be integrated into various coastal structures [104]
  • Efficiency can be affected by variations in wave height and period
  • Limited to specific locations with suitable wave conditions [142]
Overtopping
  • Can be integrated into existing harbour structures or artificial breakwaters [147]
  • Suitable for a wide range of wave conditions
  • Requires a substantial reservoir volume
  • Efficiency can be affected by variations in wave height and period [148]
The distribution of different Power Take-Off (PTO) systems applied to the OBs in existing hybrid wind–wave systems from 2012 to 2023 is depicted in Figure 19b. Hydraulic PTO systems are widely used due to their extended operating life and effective control of power fluctuations [149]. In contrast, direct-drive PTO systems require numerous electrical components in the backend power grid to control their power fluctuations during energy transmission, which increases their energy losses [150].

4.3. Energy Coupling Technologies

Electrical coupling schemes account for a large proportion of energy coupling technologies due to their maturity. A detailed comparison of AC and DC coupling is presented in Table 4. AC coupling schemes have the advantages of simple structures and low construction costs. However, they are inevitably affected by cable capacitance, which leads to high energy losses and severe harmonic interactions [151]. With an increase in the cable length, the energy losses increase rapidly. Therefore, AC coupling may be a cost-effective choice for small-capacity hybrid wind–wave systems with short-distance transmission cables. In contrast, DC coupling schemes can effectively regulate active and reactive power, presenting advantages such as a stronger fault ride-through capability, fewer control parameters, and increased reliability and flexibility. Consequently, DC coupling has a lower LCOE than AC coupling and has garnered increasing attention.
The number of relevant studies on hydraulic coupling schemes is fewer than those on electrical coupling schemes. However, existing hydraulic coupling schemes exhibit an excellent overall performance, including high energy coupling efficiency, low maintenance costs, and a long operating life. Hydraulic coupling schemes also exhibit strong adaptability under different operating conditions, which increases the economy of the system [156]. A detailed comparison between hydraulic coupling and electrical coupling is presented in Table 5. Compared to electrical coupling schemes, hydraulic coupling schemes have a longer operating life due to their simpler structures. Moreover, hydraulic transmission systems exhibit lower energy losses than electrical transmission systems [63].
Furthermore, the selection of energy coupling schemes must consider backend energy transmission systems. High-voltage direct current (HVDC) and high-voltage alternating current (HVAC) are the primary energy transmission modes in ocean energy generation systems [159]. An HVDC is more suitable for systems requiring long-distance transmission with high controllability and stability [160]. Conversely, an HVAC is preferable for systems with shorter distances and lower costs. DC coupling schemes can directly employ HVDC technology to transmit electrical energy to power stations. AC and hydraulic coupling schemes can utilise an HVAC for transmitting electrical energy to a power station, although it is only suitable for short-distance power transmission. AC coupling schemes can rectify alternating currents into direct currents before employing HVDC for power transmission; however, their energy losses increase [161]. Due to their high energy coupling efficiency, hydraulic coupling schemes can rectify alternating current into direct current and utilise HVDC for power transmission. With the rapid development of offshore renewable energy generation systems in deep water, both DC coupling and hydraulic coupling are expected to become the mainstream schemes in the future.

4.4. Seasonal Influences

Wind patterns can vary seasonally, at certain times of the year. In regions with pronounced wind seasonality, the energy output of the wind turbines within hybrid systems may fluctuate accordingly. This can affect the overall energy production and reliability of the system, requiring adjustments in energy management and grid integration strategies [31]. Similar to wind, wave patterns can also exhibit seasonal variability, with changes in wave height, period, and direction throughout the year [162]. Seasonal variations in wave energy can influence the performance of the wave energy converters within hybrid systems, impacting their energy capture efficiency and overall output. Design changes should be made to optimize the system’s performance under different wave conditions. In addition, exposure to harsh weather conditions during certain seasons increases the risk of the corrosion, erosion, or mechanical wear of system components [163], necessitating enhanced maintenance and monitoring protocols.

4.5. Technological Gaps

To accelerate the development of hybrid wind–wave systems, some challenges in energy conversion and coupling subsystems must be overcome:
  • Short operating lives. Most hybrid wind–wave systems employ OBs. Damage to their mechanical components significantly decreases their operating life.
  • Low energy production. The development of energy conversion and coupling technologies for hybrid wind–wave systems is still in its early stages. Energy production has not yet reached its maximum level.
  • Limited economic viability. High maintenance costs reduce the economy of these systems.
  • Scarcity of theoretical research and experimental tests. At present, there are a limited number of studies on the energy conversion and coupling technologies of hybrid wind–wave systems. The existing numerical models and experimental studies are not sufficient to support their further development.

4.6. Technology Development Forecasts

In this section, development forecasts for the energy conversion and coupling technologies of hybrid wind–wave systems are presented.
In terms of energy conversion technologies, integrating oscillating water column devices and hydraulic wind turbines into hybrid wind–wave systems has the potential to enhance their operating life, energy production, and system economy [45]. This will be a future research trend. Existing studies on energy coupling technologies are scarce. Therefore, theoretical innovations and novel technical schemes are required. DC coupling and hydraulic coupling will be the mainstream schemes in the future, considering their reliability, energy transmission efficiency, construction costs, and applicability in deep-sea environments [63,109].

5. Conclusions

This study provides a complete review of the energy conversion and coupling technologies of existing hybrid wind–wave systems that have not been comprehensively reviewed before. Our original contributions include a detailed classification and comparison of energy conversion and coupling technologies, the identification of existing technological gaps, and forecasts on the development of these technologies. Based on the obtained information, the following conclusions were drawn:
(1)
Mechanical–electrical wind energy conversion schemes account for a large proportion of existing hybrid wind–wave systems. However, mechanical–hydraulic schemes have more prominent advantages, including compact sizes, simple control methods, high reliability, high energy transmission efficiency, and low economic costs.
(2)
The use percentages of different wave energy conversion schemes from 2012 to 2023 were presented. The percentages schemes implementing OBs, OWCs, and overtopping systems were 58%, 34%, and 8%, respectively.
(3)
Of the different wave energy conversion technologies, OWCs have the most balanced LCOE. Integrating oscillating water column devices and hydraulic wind turbines into hybrid wind–wave systems is the most promising choice.
(4)
The distribution of the different PTO systems applied to the OBs in existing hybrid wind–wave systems from 2012 to 2023 was presented. Hydraulic PTO systems account for 73% of OBs, whereas direct-drive PTO systems account for 27%.
(5)
DC and hydraulic coupling are expected to become mainstream schemes in the future. There remains a large innovative space for energy coupling technologies.
(6)
Seasonal factors are crucial for the sustainable development of hybrid wind–wave power generation systems.
(7)
Existing challenges in energy conversion and coupling technologies include their short operating life, low energy production, limited economic viability, and the scarcity of theoretical research and experimental tests.

Author Contributions

Conceptualization, P.Q. and D.Z.; validation, B.W., Z.S., Z.L. and Y.Z.; formal analysis, B.Z.; investigation, J.X.; resources, B.W.; writing—original draft preparation, B.W.; writing—review and editing, P.Q. and D.Z.; project administration and funding acquisition, P.Q. and D.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Key R&D Program of China (Grant No. 2023YFB4204103), National Natural Science Foundation of China (Grant No. 52371292), Key Research and Development Program of Zhejiang Province (Grant No. 2023C03121), Key Research and Development Program of Hainan Province (Grant No. ZDYF2024GXJS028 and ZDYF2022GXJS221), Science and Technology Innovation Joint Project of Hainan Province (Grant No. 2021CXLH0022), and the Bureau of Science and Technology of Zhoushan (Grant No. 2023C81008).

Acknowledgments

We are grateful for the support of the above-mentioned funding bodies and the help of our colleagues from the ocean college of Zhejiang University.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Poudyal, R.; Loskot, P.; Nepal, R.; Parajuli, R.; Khadka, S.K. Mitigating the current energy crisis in Nepal with renewable energy sources. Renew. Sustain. Energy Rev. 2019, 116, 109388. [Google Scholar] [CrossRef]
  2. Rellán, A.G.; Ares, D.V.; Brea, C.V.; López, A.F.; Bugallo, P.M.B. Sources, sinks and transformations of plastics in our oceans: Review, management strategies and modelling. Sci. Total Environ. 2022, 854, 158745. [Google Scholar] [CrossRef] [PubMed]
  3. Li, M.; Luo, H.; Zhou, S.; Senthil Kumar, G.M.; Guo, X.; Law, T.C.; Cao, S. State-of-the-art review of the flexibility and feasibility of emerging offshore and coastal ocean energy technologies in East and Southeast Asia. Renew. Sustain. Energy Rev. 2022, 162, 112404. [Google Scholar] [CrossRef]
  4. Chakraborty, S.; Dwivedi, P.; Chatterjee, S.K.; Gupta, R. Factors to Promote Ocean Energy in India. Energy Policy 2021, 159, 112641. [Google Scholar] [CrossRef]
  5. Chakraborty, S.; Dwivedi, P.; Gupta, R.; Yadavalli, N. Review of Global Ocean Energy Policies in View of Lessons for India. 2018. Available online: https://www.iea.org/reports/india-2020 (accessed on 4 April 2024).
  6. Galdies, C.; Bellerby, R.; Canu, D.; Chen, W.; Garcia-Luque, E.; Gašparović, B.; Godrijan, J.; Lawlor, P.J.; Maes, F.; Malej, A.; et al. European policies and legislation targeting ocean acidification in european waters—Current state. Mar. Policy 2020, 118, 103947. [Google Scholar] [CrossRef]
  7. Ma, C.L. Ocean Energy Management Policy in China. Procedia Comput. Sci. 2019, 154, 493–499. [Google Scholar] [CrossRef]
  8. de Matos Sá, M.; Correia da Fonseca, F.X.; Amaral, L.; Castro, R. Optimising O&M scheduling in offshore wind farms considering weather forecast uncertainty and wake losses. Ocean Eng. 2024, 301, 117518. [Google Scholar]
  9. Costoya, X.; deCastro, M.; Carvalho, D.; Feng, Z.; Gómez-Gesteira, M. Climate change impacts on the future offshore wind energy resource in China. Renew. Energy 2021, 175, 731–747. [Google Scholar] [CrossRef]
  10. Hoeser, T.; Kuenzer, C. Global dynamics of the offshore wind energy sector monitored with Sentinel-1: Turbine count, installed capacity and site specifications. Int. J. Appl. Earth Obs. Geoinf. 2022, 112, 102957. [Google Scholar] [CrossRef]
  11. Ai, C.; Zhang, L.; Gao, W.; Yang, G.; Wu, D.; Chen, L.; Chen, W.; Plummer, A. A review of energy storage technologies in hydraulic wind turbines. Energy Convers. Manag. 2022, 264, 115584. [Google Scholar] [CrossRef]
  12. Liu, X.; Li, N.; Mu, H.; Li, M.; Liu, X. Techno-energy-economic assessment of a high capacity offshore wind-pumped-storage hybrid power system for regional power system. J. Energy Storage 2021, 41, 102892. [Google Scholar] [CrossRef]
  13. Wu, Y.; Zhang, T. Risk assessment of offshore wave-wind-solar-compressed air energy storage power plant through fuzzy comprehensive evaluation model. Energy 2021, 223, 120057. [Google Scholar] [CrossRef]
  14. Zhang, Y.; Ma, C.; Yang, Y.; Pang, X.; Lian, J.; Wang, X. Capacity configuration and economic evaluation of a power system integrating hydropower, solar, and wind. Energy 2022, 259, 125012. [Google Scholar] [CrossRef]
  15. Wang, Y.; Liu, Z.; Wang, H. Proposal and layout optimization of a wind-wave hybrid energy system using GPU-accelerated differential evolution algorithm. Energy 2022, 239, 121850. [Google Scholar] [CrossRef]
  16. Soliman, M.S.; Belkhier, Y.; Ullah, N.; Achour, A.; Alharbi, Y.M.; Al Alahmadi, A.A.; Abeida, H.; Khraisat, Y.S.H. Supervisory energy management of a hybrid battery/PV/tidal/wind sources integrated in DC-microgrid energy storage system. Energy Rep. 2021, 7, 7728–7740. [Google Scholar] [CrossRef]
  17. Cabrera, P.; Folley, M.; Carta, J.A. Design and performance simulation comparison of a wave energy-powered and wind-powered modular desalination system. Desalination 2021, 514, 115173. [Google Scholar] [CrossRef]
  18. Baykov, A.; Dar’enkov, A.; Kurkin, A.; Sosnina, E. Mathematical modelling of a tidal power station with diesel and wind units. J. King Saud Univ. Sci. 2019, 31, 1491–1498. [Google Scholar] [CrossRef]
  19. Astariz, S.; Iglesias, G. Output power smoothing and reduced downtime period by combined wind and wave energy farms. Energy 2016, 97, 69–81. [Google Scholar] [CrossRef]
  20. Wimalaratna, Y.P.; Afrouzi, H.N.; Mehranzamir, K.; Siddique, M.B.M.; Liew, S.C.; Ahmed, J. Analysing wind power penetration in hybrid energy systems based on techno-economic assessments. Sustain. Energy Technol. Assess. 2022, 53, 102538. [Google Scholar] [CrossRef]
  21. Castro-Santos, L.; Martins, E.; Guedes Soares, C. Economic comparison of technological alternatives to harness offshore wind and wave energies. Energy 2017, 140, 1121–1130. [Google Scholar] [CrossRef]
  22. Masoumi, M. Ocean data classification using unsupervised machine learning: Planning for hybrid wave-wind offshore energy devices. Ocean Eng. 2021, 219, 108387. [Google Scholar] [CrossRef]
  23. Qian, P.; Zhang, D.; Tian, X.; Si, Y.; Li, L. A novel wind turbine condition monitoring method based on cloud computing. Renew. Energy 2019, 135, 390–398. [Google Scholar] [CrossRef]
  24. Quevedo, E.; Delory, E.; Castro, A.; Llinás, O.; Hernandez Brito, J.; Consortium, T. Modular multi-purpose offshore platforms, the TROPOS project approach. In Proceedings of the 4th International Conference on Ocean Energy, Dublin, Ireland, 17–20 October 2012. [Google Scholar]
  25. Lakkoju, V.N.M.R. Combined power generation with wind and ocean waves. Renew. Energy 1996, 9, 870–874. [Google Scholar] [CrossRef]
  26. Pérez-Collazo, C.; Greaves, D.; Iglesias, G. A review of combined wave and offshore wind energy. Renew. Sustain. Energy Rev. 2015, 42, 141–153. [Google Scholar] [CrossRef]
  27. Schwanitz, V.J.; Wierling, A. Offshore wind investments—Realism about cost developments is necessary. Energy 2016, 106, 170–181. [Google Scholar] [CrossRef]
  28. Castro-Santos, L.; Filgueira-Vizoso, A.; Carral-Couce, L.; Formoso, J.Á.F. Economic feasibility of floating offshore wind farms. Energy 2016, 112, 868–882. [Google Scholar] [CrossRef]
  29. Patel, R.P.; Nagababu, G.; Kachhwaha, S.S.; Kumar, S.V.A.; Seemanth, M. Combined wind and wave resource assessment and energy extraction along the Indian coast. Renew. Energy 2022, 195, 931–945. [Google Scholar] [CrossRef]
  30. Ragab, A.M.; Shehata, A.S.; Elbatran, A.H.; Kotb, M.A. Numerical optimization of hybrid wind-wave farm layout located on Egyptian North Coasts. Ocean Eng. 2021, 234, 109260. [Google Scholar] [CrossRef]
  31. Gao, Q.; Khan, S.S.; Sergiienko, N.; Ertugrul, N.; Hemer, M.; Negnevitsky, M.; Ding, B. Assessment of wind and wave power characteristic and potential for hybrid exploration in Australia. Renew. Sustain. Energy Rev. 2022, 168, 112747. [Google Scholar] [CrossRef]
  32. Contestabile, P.; Russo, S.; Azzellino, A.; Cascetta, F.; Vicinanza, D. Combination of local sea winds/land breezes and nearshore wave energy resource: Case study at MaRELab (Naples, Italy). Energy Convers. Manag. 2022, 257, 115356. [Google Scholar] [CrossRef]
  33. Stoutenburg, E.D.; Jenkins, N.; Jacobson, M.Z. Power output variations of co-located offshore wind turbines and wave energy converters in California. Renew. Energy 2010, 35, 2781–2791. [Google Scholar] [CrossRef]
  34. Saenz-Aguirre, A.; Saenz, J.; Ulazia, A.; Ibarra-Berastegui, G. Optimal strategies of deployment of far offshore co-located wind-wave energy farms. Energy Convers. Manag. 2022, 251, 114914. [Google Scholar] [CrossRef]
  35. Gaughan, E.; Fitzgerald, B. An assessment of the potential for Co-located offshore wind and wave farms in Ireland. Energy 2020, 200, 117526. [Google Scholar] [CrossRef]
  36. Li, J.; Pan, S.; Chen, Y.; Yao, Y.; Xu, C. Assessment of combined wind and wave energy in the tropical cyclone affected region:An application in China seas. Energy 2022, 260, 125020. [Google Scholar] [CrossRef]
  37. Haces-Fernandez, F.; Li, H.; Ramirez, D. A layout optimization method based on wave wake preprocessing concept for wave-wind hybrid energy farms. Energy Convers. Manag. 2021, 244, 114469. [Google Scholar] [CrossRef]
  38. Clark, C.E.; Miller, A.; DuPont, B. An analytical cost model for co-located floating wind-wave energy arrays. Renew. Energy 2019, 132, 885–897. [Google Scholar] [CrossRef]
  39. Veigas, M.; Carballo, R.; Iglesias, G. Wave and offshore wind energy on an island. Energy Sustain. Dev. 2014, 22, 57–65. [Google Scholar] [CrossRef]
  40. Moschos, E.; Manou, G.; Dimitriadis, P.; Afentoulis, V.; Koutsoyiannis, D.; Tsoukala, V.K. Harnessing wind and wave resources for a Hybrid Renewable Energy System in remote islands: A combined stochastic and deterministic approach. In Proceedings of the European Geosciences Union General Assembly 2017: Energy, Resources and the Environment (ERE): Meeting the Challenges of the Future, Vienna, Austria, 23–28 April 2017; Elsevier Ltd.: Vienna, Austria, 2017; pp. 415–424. [Google Scholar]
  41. Vieira da Silva, G.; Toldo Jr, E.E.; Klein, A.H.d.F.; Short, A.D. The influence of wave-, wind- and tide-forced currents on headland sand bypassing—Study case: Santa Catarina Island north shore, Brazil. Geomorphology 2018, 312, 1–11. [Google Scholar] [CrossRef]
  42. Astariz, S.; Iglesias, G. Selecting optimum locations for co-located wave and wind energy farms. Part II: A case study. Energy Convers. Manag. 2016, 122, 599–608. [Google Scholar] [CrossRef]
  43. Villalba, J.; Abdussamie, N.; Aryai, V.; Nikolova, N.; Tenekedjiev, K.; Wang, C.-M.; Penesis, I. Assessment of uncertain alternatives for co-located aquaculture and offshore wind farm in tasmania. Ocean Eng. 2022, 249, 110949. [Google Scholar] [CrossRef]
  44. Astariz, S.; Vazquez, A.; Sánchez, M.; Carballo, R.; Iglesias, G. Co-located wave-wind farms for improved O&M efficiency. Ocean Coast. Manag. 2018, 163, 66–71. [Google Scholar]
  45. Dong, X.; Li, Y.; Li, D.; Cao, F.; Jiang, X.; Shi, H. A state-of-the-art review of the hybrid wind-wave energy converter. Prog. Energy 2022, 4, 042004. [Google Scholar] [CrossRef]
  46. El-Sattar, H.A.; Sultan, H.M.; Kamel, S.; Khurshaid, T.; Rahmann, C. Optimal design of stand-alone hybrid PV/wind/biomass/battery energy storage system in Abu-Monqar, Egypt. J. Energy Storage 2021, 44, 103336. [Google Scholar] [CrossRef]
  47. Lucas, T.R.; Ferreira, A.F.; Santos Pereira, R.B.; Alves, M. Hydrogen production from the WindFloat Atlantic offshore wind farm: A techno-economic analysis. Appl. Energy 2022, 310, 118481. [Google Scholar] [CrossRef]
  48. Rasool, S.; Muttaqi, K.M.; Sutanto, D.; Hemer, M. Quantifying the reduction in power variability of co-located offshore wind-wave farms. Renew. Energy 2022, 185, 1018–1033. [Google Scholar] [CrossRef]
  49. Giudici, F.; Garofalo, E.; Bozzi, S.; Castelletti, A. Climate uncertainty and technological innovation shape investments in renewable energy for small off-grid islands. Renew. Sustain. Energy Transit. 2022, 2, 100036. [Google Scholar] [CrossRef]
  50. Chen, Z.; Sun, J.; Yang, J.; Sun, Y.; Chen, Q.; Zhao, H.; Qian, P.; Si, Y.; Zhang, D. Experimental and numerical analysis of power take-off control effects on the dynamic performance of a floating wind-wave combined system. Renew. Energy 2024, 226, 120353. [Google Scholar] [CrossRef]
  51. Vasileiou, M.; Loukogeorgaki, E.; Vagiona, D.G. GIS-based multi-criteria decision analysis for site selection of hybrid offshore wind and wave energy systems in Greece. Renew. Sustain. Energy Rev. 2017, 73, 745–757. [Google Scholar] [CrossRef]
  52. Kardakaris, K.; Boufidi, I.; Soukissian, T. Offshore wind and wave energy complementarity in the greek seas based on ERA5 data. Atmosphere 2021, 12, 1360. [Google Scholar] [CrossRef]
  53. Haces-Fernandez, F.; Li, H.; Ramirez, D. Assessment of the potential of energy extracted from waves and wind to supply offshore oil platforms operating in the gulf of Mexico. Energies 2018, 11, 1084. [Google Scholar] [CrossRef]
  54. Curto, D.; Doan, B.V.; Franzitta, V.; Montana, F.; Nguyen, N.Q.; Sanseverino, E.R. Wave and Wind Energy Systems Integration in Vietnam: Analysis of Energy Potential and Economic Feasibility. In Proceedings of the 2020 IEEE International Conference on Environment and Electrical Engineering and 2020 IEEE Industrial and Commercial Power Systems Europe (EEEIC/I&CPS Europe), Madrid, Spain, 9–12 June 2020; pp. 1–6. [Google Scholar]
  55. Wan, L.; Ren, N.; Zhang, P. Numerical investigation on the dynamic responses of three integrated concepts of offshore wind and wave energy converter. Ocean Eng. 2020, 217, 107896. [Google Scholar] [CrossRef]
  56. Perez-Collazo, C.; Pemberton, R.; Greaves, D.; Iglesias, G. Monopile-mounted wave energy converter for a hybrid wind-wave system. Energy Convers. Manag. 2019, 199, 111971. [Google Scholar] [CrossRef]
  57. Wang, Y.; Shi, W.; Michailides, C.; Wan, L.; Kim, H.; Li, X. WEC shape effect on the motion response and power performance of a combined wind-wave energy converter. Ocean Eng. 2022, 250, 111038. [Google Scholar] [CrossRef]
  58. Ghafari, H.R.; Ghassemi, H.; Abbasi, A.; Vakilabadi, K.A.; Yazdi, H.; He, G. Novel concept of hybrid wavestar- floating offshore wind turbine system with rectilinear arrays of WECs. Ocean Eng. 2022, 262, 112253. [Google Scholar] [CrossRef]
  59. Zhang, D.; Liu, D.; Liu, X.; Xu, H.; Wang, Y.; Bi, R.; Qian, P. Unsteady effects of a winglet on the performance of horizontal-axis tidal turbine. Renew. Energy 2024, 225, 120334. [Google Scholar] [CrossRef]
  60. Zhang, D.; Li, C.; Bi, R.; Huang, X.; Sun, Z.; Lan, T.; Wang, Y.; Huang, T.; Qian, P. Conversion mechanism for solving the end-stop problem of hydraulic power take-off system for wave energy. Ocean Eng. 2024, 294, 116776. [Google Scholar] [CrossRef]
  61. Zhang, D.; Wang, Y.; Jiang, Y.; Zhao, T.; Xu, H.; Qian, P.; Li, C. A Novel Wind Turbine Rolling Element Bearing Fault Diagnosis Method Based on CEEMDAN and Improved TFR Demodulation Analysis. Energies 2024, 17, 819. [Google Scholar] [CrossRef]
  62. Kamarlouei, M.; Gaspar, J.F.; Calvario, M.; Hallak, T.S.; Mendes, M.J.G.C.; Thiebaut, F.; Guedes Soares, C. Experimental study of wave energy converter arrays adapted to a semi-submersible wind platform. Renew. Energy 2022, 188, 145–163. [Google Scholar] [CrossRef]
  63. Wang, B.; Deng, Z.; Zhang, B. Simulation of a novel wind–wave hybrid power generation system with hydraulic transmission. Energy 2022, 238, 121833. [Google Scholar] [CrossRef]
  64. Lu, S.Y.; Wang, L.; Lo, T.M.; Prokhorov, A.V. Integration of Wind Power and Wave Power Generation Systems Using a DC Microgrid. IEEE Trans. Ind. Appl. 2015, 51, 2753–2761. [Google Scholar] [CrossRef]
  65. Luo, H.; Cao, S. Advanced energy flexibility enhancement via the novel resources of wave energy converter reservoirs and electric storages for a hybrid wave-wind energy supported hotel energy system. J. Build. Eng. 2022, 60, 105167. [Google Scholar] [CrossRef]
  66. Chen, M.; Huang, L.; Yang, J.; Lyu, Y. Design and simulation of multi-energy hybrid power system based on wave and wind energy. In Proceedings of the 2017 20th International Conference on Electrical Machines and Systems (ICEMS), Sydney, Australia, 11–14 August 2017; pp. 1–6. [Google Scholar]
  67. Feng, B.; Xu, H.; Wang, B.; Wang, Y.; Zhu, Y.; Bi, R.; Zhang, D.; Qian, P. Design, modeling and experiments of swing L-shape piezoelectric beam applied to tidal and wave energy harvesting. Ocean Eng. 2023, 289, 116193. [Google Scholar] [CrossRef]
  68. McTiernan, K.L.; Sharman, K.T. Review of Hybrid Offshore Wind and Wave Energy Systems. In Proceedings of the North American Wind Energy Academy, NAWEA 2019 and the International Conference on Future Technologies in Wind Energy 2019, WindTech 2019, Amherst, MA, USA, 14–16 October 2019; IOP Publishing Ltd.: Amherst, MA, USA, 2020. [Google Scholar]
  69. Subbulakshmi, A.; Verma, M.; Keerthana, M.; Sasmal, S.; Harikrishna, P.; Kapuria, S. Recent advances in experimental and numerical methods for dynamic analysis of floating offshore wind turbines An integrated review. Renew. Sustain. Energy Rev. 2022, 164, 112525. [Google Scholar] [CrossRef]
  70. Roy, A.; Auger, F.; Dupriez-Robin, F.; Bourguet, S.; Tran, Q.T. Electrical power supply of remote maritime areas: A review of hybrid systems based on marine renewable energies. Energies 2018, 11, 1904. [Google Scholar] [CrossRef]
  71. Creen Ocean Energy Wave Treader. Available online: https://www.power-technology.com/projects/greenoceanenergywav/ (accessed on 1 January 2024).
  72. Pelagic Power AS. W2Power Web Page; Pelagic Power AS: London, UK, 2010. [Google Scholar]
  73. Floating Power Plant AS. Poseidon Floating Power Web Page; Floating Power Plant AS: Bandholm, Denmark, 2013. [Google Scholar]
  74. Principle Power Inc. WindFloat Web Page; Principle Power Inc.: Emeryville, CA, USA, 2011. [Google Scholar]
  75. Lu, K.-H.; Hong, C.-M.; Xu, Q. Recurrent wavelet-based Elman neural network with modified gravitational search algorithm control for integrated offshore wind and wave power generation systems. Energy 2019, 170, 40–52. [Google Scholar] [CrossRef]
  76. Talaat, M.; Farahat, M.A.; Elkholy, M.H. Renewable power integration: Experimental and simulation study to investigate the ability of integrating wave, solar and wind energies. Energy 2019, 170, 668–682. [Google Scholar] [CrossRef]
  77. Qian, P.; Ma, X.; Zhang, D.; Wang, J. Data-driven condition monitoring approaches to improving power output of wind turbines. IEEE Trans. Ind. Electron. 2019, 66, 6012–6020. [Google Scholar] [CrossRef]
  78. Zhang, D.; Chen, Z.; Liu, X.; Sun, J.; Yu, H.; Zeng, W.; Ying, Y.; Sun, Y.; Cui, L.; Yang, S.; et al. A coupled numerical framework for hybrid floating offshore wind turbine and oscillating water column wave energy converters. Energy Convers. Manag. 2022, 267, 115933. [Google Scholar] [CrossRef]
  79. Wei, G.; Jiani, G.; Lin, Z.; Pengfei, Z.; Die, W.; Lijuan, C.; Chao, A. Bivariate active power control of energy storage hydraulic wind turbine. J. Energy Storage 2022, 55, 105433. [Google Scholar] [CrossRef]
  80. Korkos, P.; Linjama, M.; Kleemola, J.; Lehtovaara, A. Data annotation and feature extraction in fault detection in a wind turbine hydraulic pitch system. Renew. Energy 2022, 185, 692–703. [Google Scholar] [CrossRef]
  81. Roggenburg, M.; Esquivel-Puentes, H.A.; Vacca, A.; Bocanegra Evans, H.; Garcia-Bravo, J.M.; Warsinger, D.M.; Ivantysynova, M.; Castillo, L. Techno-economic analysis of a hydraulic transmission for floating offshore wind turbines. Renew. Energy 2020, 153, 1194–1204. [Google Scholar] [CrossRef]
  82. Yang, R.-Y.; Wang, C.-W.; Huang, C.-C.; Chung, C.-H.; Chen, C.-P.; Huang, C.-J. The 1:20 scaled hydraulic model test and field experiment of barge-type floating offshore wind turbine system. Ocean Eng. 2022, 247, 110486. [Google Scholar] [CrossRef]
  83. Burhanudin, J.; Hasim, A.S.A.; Ishak, A.M.; Burhanudin, J.; Dardin, S.M.F.B.S.M. A Review of Power Electronics for Nearshore Wave Energy Converter Applications. IEEE Access 2022, 10, 16670–16680. [Google Scholar] [CrossRef]
  84. Cai, Y.; Huo, Y.; Shi, X.; Liu, Y. Numerical and experimental research on a resonance-based wave energy converter. Energy Convers. Manag. 2022, 269, 116152. [Google Scholar] [CrossRef]
  85. Nielsen, S.R.K.; Zhou, Q.; Basu, B.; Sichani, M.T.; Kramer, M.M. Optimal control of an array of non-linear wave energy point converters. Ocean Eng. 2014, 88, 242–254. [Google Scholar] [CrossRef]
  86. Babarit, A.; Hals, J.; Muliawan, M.J.; Kurniawan, A.; Moan, T.; Krokstad, J. Numerical benchmarking study of a selection of wave energy converters. Renew. Energy 2012, 41, 44–63. [Google Scholar] [CrossRef]
  87. Li, L.; Jia, Q.; Wan, Z.; Zhang, Y.; Qian, P.; Li, J. Experimental and numerical investigation of effects of residual stress and its release on fatigue strength of typical FPSO-unit welded joint. Ocean Eng. 2020, 196, 106858. [Google Scholar] [CrossRef]
  88. Ciappi, L.; Simonetti, I.; Bianchini, A.; Cappietti, L.; Manfrida, G. Application of integrated wave-to-wire modelling for the preliminary design of oscillating water column systems for installations in moderate wave climates. Renew. Energy 2022, 194, 232–248. [Google Scholar] [CrossRef]
  89. Wave Star AS. Wave Star Energy Web Page; Wave Star AS: Sønderborg, Denmark, 2012. [Google Scholar]
  90. Pelamis Wave Power. Pelamis Wave Power Web Page; Pelamis Wave Power: Edinburgh, UK, 2014. [Google Scholar]
  91. Karimirad, M.; Koushan, K. WindWEC: Combining wind and wave energy inspired by hywind and wavestar. In Proceedings of the 2016 IEEE International Conference on Renewable Energy Research and Applications (ICRERA), Bermigham, UK, 20–23 November 2016; pp. 96–101. [Google Scholar]
  92. Zhang, X.; Yang, J. Power capture performance of an oscillating-body WEC with nonlinear snap through PTO systems in irregular waves. Appl. Ocean Res. 2015, 52, 261–273. [Google Scholar] [CrossRef]
  93. Si, Y.; Chen, Z.; Zeng, W.; Sun, J.; Zhang, D.; Ma, X.; Qian, P. The influence of power-take-off control on the dynamic response and power output of combined semi-submersible floating wind turbine and point-absorber wave energy converters. Ocean Eng. 2021, 227, 108835. [Google Scholar] [CrossRef]
  94. Wei, Z.; Shi, H.; Cao, F.; Yu, M.; Li, M.; Chen, Z.; Liu, P. Study on the power performance of wave energy converters mounted around an offshore wind turbine jacket platform. Renew. Energy 2024, 221, 119786. [Google Scholar] [CrossRef]
  95. Amini, E.; Mehdipour, H.; Faraggiana, E.; Golbaz, D.; Mozaffari, S.; Bracco, G.; Neshat, M. Optimization of hydraulic power take-off system settings for point absorber wave energy converter. Renew. Energy 2022, 194, 938–954. [Google Scholar] [CrossRef]
  96. Gaspar, J.F.; Calvário, M.; Kamarlouei, M.; Guedes Soares, C. Power take-off concept for wave energy converters based on oil-hydraulic transformer units. Renew. Energy 2016, 86, 1232–1246. [Google Scholar] [CrossRef]
  97. Lihui, X.; Tao, G.; Wenquan, W. Effects of Vortex Structure on Hydraulic Loss in a Low Head Francis Turbine under Overall Operating Conditions Base on Entropy Production Method. Renew. Energy 2022, 198, 367–379. [Google Scholar] [CrossRef]
  98. Szabó, L. On the use of rotary-linear generators in floating hybrid wind and wave energy conversion systems. In Proceedings of the 2018 IEEE International Conference on Automation, Quality and Testing, Robotics (AQTR), Cluj-Napoca, Romania, 24–26 May 2018; pp. 1–6. [Google Scholar]
  99. Rahman, M.A.; Islam, M.R.; Muttaqi, K.M.; Sutanto, D. Modeling and Design of a Multiport Magnetic Bus-Based Novel Wind-Wave Hybrid Ocean Energy Technology. IEEE Trans. Ind. Appl. 2021, 57, 5400–5410. [Google Scholar] [CrossRef]
  100. Rasool, S.; Muttaqi, K.M.; Sutanto, D. A Novel Configuration of a Hybrid Wind-Wave Energy Harvesting System for a Remote Island. In Proceedings of the 2021 IEEE Industry Applications Society Annual Meeting (IAS), Baltimore, MD, USA, 10–14 October 2021; pp. 1–6. [Google Scholar]
  101. Rasool, S.; Muttaqi, K.M.; Sutanto, D. Integration of a Wind-Wave Hybrid Energy System with the Distribution Network. In Proceedings of the 2022 IEEE International Conference on Power Electronics, Smart Grid, and Renewable Energy (PESGRE), Kerala, India, 2–5 January 2022; pp. 1–6. [Google Scholar]
  102. Anastas, G.; Alfredo Santos, J.; Fortes, C.J.E.M.; Pinheiro, L.V. Energy assessment of potential locations for OWC instalation at the Portuguese coast. Renew. Energy 2022. [Google Scholar] [CrossRef]
  103. Faÿ, F.-X.; Henriques, J.C.; Kelly, J.; Mueller, M.; Abusara, M.; Sheng, W.; Marcos, M. Comparative assessment of control strategies for the biradial turbine in the Mutriku OWC plant. Renew. Energy 2020, 146, 2766–2784. [Google Scholar] [CrossRef]
  104. Ciappi, L.; Stebel, M.; Smolka, J.; Cappietti, L.; Manfrida, G. Analytical and Computational Fluid Dynamics Models of Wells Turbines for Oscillating Water Column Systems. J. Energy Resour. Technol. 2021, 144. [Google Scholar] [CrossRef]
  105. Çelik, A. An experimental investigation into the effects of front wall geometry on OWC performance for various levels of applied power take off dampings. Ocean Eng. 2022, 248, 110761. [Google Scholar] [CrossRef]
  106. Henriques, J.C.C.; Portillo, J.C.C.; Sheng, W.; Gato, L.M.C.; Falcão, A.F.O. Dynamics and control of air turbines in oscillating-water-column wave energy converters: Analyses and case study. Renew. Sustain. Energy Rev. 2019, 112, 571–589. [Google Scholar] [CrossRef]
  107. Perez-Collazo, C.; Greaves, D.; Iglesias, G. Hydrodynamic response of the WEC sub-system of a novel hybrid wind-wave energy converter. Energy Convers. Manag. 2018, 171, 307–325. [Google Scholar] [CrossRef]
  108. Cong, P.; Teng, B.; Bai, W.; Ning, D.; Liu, Y. Wave power absorption by an oscillating water column (OWC) device of annular cross-section in a combined wind-wave energy system. Appl. Ocean Res. 2021, 107, 102499. [Google Scholar] [CrossRef]
  109. Aboutalebi, P.; Garrido, A.J.; Garrido, I.; Nguyen, D.T.; Gao, Z. Hydrostatic stability and hydrodynamics of a floating wind turbine platform integrated with oscillating water columns: A design study. Renew. Energy 2024, 221, 119824. [Google Scholar] [CrossRef]
  110. Han, Z.; Liu, Z.; Shi, H. Numerical study on overtopping performance of a multi-level breakwater for wave energy conversion. Ocean Eng. 2018, 150, 94–101. [Google Scholar] [CrossRef]
  111. Liu, Z.; Shi, H.; Cui, Y.; Kim, K. Experimental study on overtopping performance of a circular ramp wave energy converter. Renew. Energy 2017, 104, 163–176. [Google Scholar] [CrossRef]
  112. Gleeson, J.P.; Ward, J.A.; O’Sullivan, K.P.; Lee, W.T. Competition-Induced Criticality in a Model of Meme Popularity. Phys. Rev. Lett. 2014, 112, 048701. [Google Scholar] [CrossRef] [PubMed]
  113. Fiaschi, D.; Manfrida, G.; Secchi, R.; Tempesti, D. A versatile system for offshore energy conversion including diversified storage. Energy 2012, 48, 566–576. [Google Scholar] [CrossRef]
  114. Wang, L.; Lin, C.Y.; Wu, H.Y.; Prokhorov, A.V. Stability Analysis of a Microgrid System with a Hybrid Offshore Wind and Ocean Energy Farm Fed to a Power Grid Through an HVDC Link. IEEE Trans. Ind. Appl. 2018, 54, 2012–2022. [Google Scholar] [CrossRef]
  115. Soundarya, G.; Sitharthan, R.; Sundarabalan, C.K.; Balasundar, C.; Karthikaikannan, D.; Sharma, J. Design and Modeling of Hybrid DC/AC Microgrid With Manifold Renewable Energy Sources. IEEE Can. J. Electr. Comput. Eng. 2021, 44, 130–135. [Google Scholar] [CrossRef]
  116. Qin, C.; Ju, P.; Wu, F.; Jin, Y.; Chen, Q.; Sun, L. A coordinated control method to smooth short-term power fluctuations of hybrid offshore renewable energy conversion system (HORECS). In Proceedings of the IEEE Eindhoven PowerTech, PowerTech 2015, Eindhoven, The Netherlands, 29 June–2 July 2015; Institute of Electrical and Electronics Engineers Inc.: Eindhoven, The Netherlands, 2015. [Google Scholar]
  117. Rahman, M.A.; Islam, M.R.; Muttaqi, K.M.; Sutanto, D. Modeling and Design of a Multiport Magnetic Bus Based Novel Wind-Wave Hybrid Ocean Energy Generation Technology. In Proceedings of the 2020 IEEE Industry Applications Society Annual Meeting, Detroit, MI, USA, 10–16 October 2020; pp. 1–6. [Google Scholar]
  118. Lu, S.Y.; Wang, L.; Lo, T.M. Integration of wind-power and wave-power generation systems using a DC micro grid. In Proceedings of the 2014 IEEE Industry Application Society Annual Meeting, Nashville, TN, USA, 29 October–2 November 2023. [Google Scholar]
  119. Rasool, S.; Muttaqi, K.M.; Sutanto, D. A Co-ordinated Real and Reactive Power Control Architecture of a Grid-Connected Hybrid Offshore Wind-Wave Energy Conversion System. In Proceedings of the 2022 IEEE Industry Applications Society Annual Meeting (IAS), Detroit, MI, USA, 9–14 October 2022; pp. 1–6. [Google Scholar]
  120. Zhao, X.; Yan, Z.; Zhang, X. A Wind-Wave Farm System With Self-Energy Storage and Smoothed Power Output. IEEE Access 2016, 4, 8634–8642. [Google Scholar] [CrossRef]
  121. Rasool, S.; Muttaqi, K.M.; Sutanto, D. A Novel Configuration of a Hybrid Offshore Wind-Wave Energy Conversion System and its Controls for a Remote Area Power Supply. IEEE Trans. Ind. Appl. 2022, 58, 7805–7817. [Google Scholar] [CrossRef]
  122. Wang, L.; Jan, S.R.; Li, C.N.; Li, H.W.; Huang, Y.H.; Chen, Y.T.; Wang, S.W. Study of a hybrid offshore wind and seashore wave farm connected to a large power grid through a flywheel energy storage system. In Proceedings of the 2011 IEEE Power and Energy Society General Meeting, Detroit, MI, USA, 24–28 July 2011; pp. 1–7. [Google Scholar]
  123. Gao, Q.; Ding, B.; Ertugrul, N.; Li, Y. Impacts of mechanical energy storage on power generation in wave energy converters for future integration with offshore wind turbine. Ocean Eng. 2022, 261, 112136. [Google Scholar] [CrossRef]
  124. Kluger, J.M.; Haji, M.N.; Slocum, A.H. The power balancing benefits of wave energy converters in offshore wind-wave farms with energy storage. Appl. Energy 2023, 331, 120389. [Google Scholar] [CrossRef]
  125. Chen, W.; Gao, F.; Meng, X.; Chen, B.; Ren, A. W2P: A high-power integrated generation unit for offshore wind power and ocean wave energy. Ocean Eng. 2016, 128, 41–47. [Google Scholar] [CrossRef]
  126. Shi, M.; Li, W.; Lin, Y.; Liu, H.; Zhang, D.; Ma, S. Modeling and simulation of wind-wave energy hybrid power system based on hydraulic transmission. Taiyangneng Xuebao/Acta Energiae Solaris Sin. 2013, 34, 1257–1263. [Google Scholar]
  127. Dang, T.D.; Phan, C.B.; Truong, H.V.A.; Le, C.D.; Nguyen, M.T.; Ahn, K.K. A study on modeling of a hybrid wind wave energy converter system. In Proceedings of the 2016 16th International Conference on Control, Automation and Systems (ICCAS), Gyeongju, Republic of Korea, 16–19 October 2016; pp. 182–187. [Google Scholar]
  128. Shi, M.; Li, W.; Lin, Y.; Liu, H.; Zhang, D.; Wu, S. A Hybrid Wind-Wave Power Generation System. Chinese Patent ZL 201110115265.2, 23 April 2011. [Google Scholar]
  129. Xu, Q.; Shi, M.; Liu, H.; Li, W.; Lin, Y.; Tu, L. A Hybrid Wind-Wave Power Generation System with Hydraulic Transmission and its Control Method. Chinese Patent ZL 201310062778.0, 28 February 2013. [Google Scholar]
  130. Kong, X.; Chen, H.; Ai, C.; Chen, L.; Yan, G. A Hybrid Wind-Wave Power Generatior Device. Chinese Patent ZL 201610589437.2, 25 July 2016. [Google Scholar]
  131. Liu, C.; Chau, K.T.; Lee, C.H.T.; Lin, F. An efficient offshore wind-wave hybrid generation system using direct-drive multitoothed rotating and linear machines. In Proceedings of the 2014 17th International Conference on Electrical Machines and Systems (ICEMS), Hangzhou, China, 22–25 October 2014; pp. 273–279. [Google Scholar]
  132. Kim, K.H.; Lee, K.; Sohn, J.M.; Park, S.W.; Hong, K. Conceptual design of 10MW class floating wave-offshore wind hybrid power generation system. In Proceedings of the ISOPE International Ocean and Polar Engineering Conference, Kona, HI, USA, 21–26 June 2015. [Google Scholar]
  133. Legaz, M.J.; Coronil, D.; Mayorga, P.; Fernandez, J. Study of a hybrid renewable energy platform: W2Power. In Proceedings of the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering, OMAE 2018, Madrid, Spain, 17–22 June 2018; American Society of Mechanical Engineers (ASME): New York, NY, USA, 2018. [Google Scholar]
  134. Sarmiento, J.; Iturrioz, A.; Ayllón, V.; Guanche, R.; Losada, I.J. Experimental modelling of a multi-use floating platform for wave and wind energy harvesting. Ocean Eng. 2019, 173, 761–773. [Google Scholar] [CrossRef]
  135. Zhu, H.; Hu, C.; Sueyoshi, M.; Yoshida, S. Integration of a semisubmersible floating wind turbine and wave energy converters: An experimental study on motion reduction. J. Mar. Sci. Technol. 2020, 25, 667–674. [Google Scholar] [CrossRef]
  136. Aboutalebi, P.; M’Zoughi, F.; Martija, I.; Garrido, I.; Garrido, A.J. Switching Control Strategy for Oscillating Water Columns Based on Response Amplitude Operators for Floating Offshore Wind Turbines Stabilization. Appl. Sci. 2021, 11, 5249. [Google Scholar] [CrossRef]
  137. Deng, Z.; Zhang, B.; Miao, Y.; Zhao, B.; Wang, Q.; Zhang, K. Multi-Objective Optimal Design of the Wind-Wave Hybrid Platform with the Coupling Interaction. J. Ocean Univ. China 2023, 22, 1165–1180. [Google Scholar] [CrossRef]
  138. O’Connell, R.; Kamidelivand, M.; Furlong, R.; Guerrini, M.; Cullinane, M.; Murphy, J. An advanced geospatial assessment of the Levelised cost of energy (LCOE) for wave farms in Irish and western UK waters. Renew. Energy 2024, 221, 119864. [Google Scholar] [CrossRef]
  139. Jaen-Sola, P.; McDonald, A.S.; Oterkus, E. Dynamic structural design of offshore direct-drive wind turbine electrical generators. Ocean Eng. 2018, 161, 1–19. [Google Scholar] [CrossRef]
  140. Mahato, A.C.; Ghoshal, S.K.; Samantaray, A.K. Reduction of wind turbine power fluctuation by using priority flow divider valve in a hydraulic power transmission. Mech. Mach. Theory 2018, 128, 234–253. [Google Scholar] [CrossRef]
  141. Youssef, R.; Colla, G. Synergistic Biostimulatory Action: Designing the Next Generation of Plant Biostimulants for Sustainable Agriculture. Front. Plant Sci. 2018, 9, 426696. [Google Scholar]
  142. Gao, Q.; Bechlenberg, A.; Jayawardhana, B.; Ertugrul, N.; Vakis, A.I.; Ding, B. Techno-economic assessment of offshore wind and hybrid wind–wave farms with energy storage systems. Renew. Sustain. Energy Rev. 2024, 192, 114263. [Google Scholar] [CrossRef]
  143. Falcão, A.F.O.; Henriques, J.C.C. Oscillating-water-column wave energy converters and air turbines: A review. Renew. Energy 2016, 85, 1391–1424. [Google Scholar] [CrossRef]
  144. Xu, C.; Liu, Z.; Tang, G. Experimental study of the hydrodynamic performance of a U-oscillating water column wave energy converter. Ocean Eng. 2022, 265, 112598. [Google Scholar] [CrossRef]
  145. Ahmed, A.; Wang, Y.; Azam, A.; Zhang, Z. Design and analysis of the bulbous-bottomed oscillating resonant buoys for an optimal point absorber wave energy converter. Ocean Eng. 2022, 263, 112443. [Google Scholar] [CrossRef]
  146. Xiao, X.; Xiao, L.; Peng, T. Comparative study on power capture performance of oscillating-body wave energy converters with three novel power take-off systems. Renew. Energy 2017, 103, 94–105. [Google Scholar] [CrossRef]
  147. Barbosa, D.V.E.; Santos, A.L.G.; dos Santos, E.D.; Souza, J.A. Overtopping device numerical study: Openfoam solution verification and evaluation of curved ramps performances. Int. J. Heat Mass Transf. 2019, 131, 411–423. [Google Scholar] [CrossRef]
  148. Contestabile, P.; Crispino, G.; Di Lauro, E.; Ferrante, V.; Gisonni, C.; Vicinanza, D. Overtopping breakwater for wave Energy Conversion: Review of state of art, recent advancements and what lies ahead. Renew. Energy 2020, 147, 705–718. [Google Scholar] [CrossRef]
  149. Liu, C.; Zhao, Z.; Hu, M.; Gao, W.; Chen, J.; Yan, H.; Zeng, Y.; Zhang, T.; Liu, X.; Yang, Q.; et al. A novel discrete control for wave energy converters with a hydraulic power take-off system. Ocean Eng. 2022, 249, 110887. [Google Scholar] [CrossRef]
  150. Falcão, A.F.d.O. Phase control through load control of oscillating-body wave energy converters with hydraulic PTO system. Ocean Eng. 2008, 35, 358–366. [Google Scholar] [CrossRef]
  151. Sreelekshmi, R.S.; Lakshmi, R.; Nair, M.G. AC microgrid with battery energy storage management under grid connected and islanded modes of operation. Energy Rep. 2022, 8, 350–357. [Google Scholar]
  152. Mishra, S.K.; Bhuyan, S.K.; Rathod, P.V. Performance analysis of a hybrid renewable generation system connected to grid in the presence of DVR. Ain Shams Eng. J. 2022, 13, 101700. [Google Scholar] [CrossRef]
  153. Çelik, Ö.; Büyük, M.; Tan, A. Mitigation of power oscillations for energy harvesting capability improvement of grid-connected renewable energy systems. Electr. Power Syst. Res. 2022, 213, 108756. [Google Scholar] [CrossRef]
  154. Zhang, J.; Bi, T.; Liu, H. Dynamic state estimation of a grid-connected converter of a renewable generation system using adaptive cubature Kalman filtering. Int. J. Electr. Power Energy Syst. 2022, 143, 108470. [Google Scholar] [CrossRef]
  155. Tu, Y.; Pei, X.; Zhou, W.; Li, P.; Wei, X.; Tang, G. An integrated multi-port hybrid DC circuit breaker for VSC-based DC grids. Int. J. Electr. Power Energy Syst. 2022, 142, 108379. [Google Scholar] [CrossRef]
  156. Zhao, Z.; Yang, J.; Chung, C.Y.; Yang, W.; He, X.; Chen, M. Performance enhancement of pumped storage units for system frequency support based on a novel small signal model. Energy 2021, 234, 121207. [Google Scholar] [CrossRef]
  157. Wang, L.; Guo, W. Nonlinear hydraulic coupling characteristics and energy conversion mechanism of pipeline—Surge tank system of hydropower station with super long headrace tunnel. Renew. Energy 2022, 199, 1345–1360. [Google Scholar] [CrossRef]
  158. He, X.; Xiao, G.; Hu, B.; Tan, L.; Tang, H.; He, S.; He, Z. The applications of energy regeneration and conversion technologies based on hydraulic transmission systems: A review. Energy Convers. Manag. 2020, 205, 112413. [Google Scholar] [CrossRef]
  159. Hassan Ashrafi Niaki, S.; Chen, Z.; Bak-Jensen, B.; Sharifabadi, K.; Liu, Z.; Hu, S. DC protection criteria for multi-terminal HVDC system considering transient stability of embedded AC grid. Int. J. Electr. Power Energy Syst. 2024, 157, 109815. [Google Scholar] [CrossRef]
  160. Darabian, M.; Jalilvand, A.; Azari, M. Power system stability enhancement in the presence of renewable energy resources and HVDC lines based on predictive control strategy. Int. J. Electr. Power Energy Syst. 2016, 80, 363–373. [Google Scholar] [CrossRef]
  161. Acosta, O.; Mandal, P.; Galvan, E.; Senjyu, T. Performance assessment of offshore and onshore wind energy systems to counterpoise residential HVAC loads. Int. J. Electr. Power Energy Syst. 2024, 157, 109830. [Google Scholar] [CrossRef]
  162. Vázquez, R.; Cabos, W.; Nieto-Borge, J.C.; Gutiérrez, C. Complementarity of offshore energy resources on the Spanish coasts: Wind, wave, and photovoltaic energy. Renew. Energy 2024, 224, 120213. [Google Scholar] [CrossRef]
  163. van der Zant, H.F.; Pillet, A.-C.; Schaap, A.; Stark, S.J.; de Weijer, T.A.; Cahyaningwidi, A.A.; Lehner, B.A.E. The energy park of the future: Modelling the combination of wave-, wind- and solar energy in offshore multi-source parks. Heliyon 2024, 10, e26788. [Google Scholar] [CrossRef]
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Figure 1. Classification of combined wind–wave power generation systems: (a) Co-located system. Reproduced with permission from [48], Elsevier (Amsterdam, The Netherlands), 2022. (b) Island system. Reproduced with permission from [49], Elsevier (Amsterdam, The Netherlands), 2022. (c) Hybrid system. Reproduced with permission from [50], Elsevier (Amsterdam, The Netherlands), 2024.
Figure 1. Classification of combined wind–wave power generation systems: (a) Co-located system. Reproduced with permission from [48], Elsevier (Amsterdam, The Netherlands), 2022. (b) Island system. Reproduced with permission from [49], Elsevier (Amsterdam, The Netherlands), 2022. (c) Hybrid system. Reproduced with permission from [50], Elsevier (Amsterdam, The Netherlands), 2024.
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Figure 2. Classification of the energy conversion technologies utilized in existing hybrid wind–wave systems.
Figure 2. Classification of the energy conversion technologies utilized in existing hybrid wind–wave systems.
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Figure 3. Mechanical–electrical wind energy conversion system. Reproduced with permission from [78], Elsevier (Amsterdam, The Netherlands), 2022.
Figure 3. Mechanical–electrical wind energy conversion system. Reproduced with permission from [78], Elsevier (Amsterdam, The Netherlands), 2022.
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Figure 4. Mechanical–hydraulic wind energy conversion system. Reproduced with permission from [81], Elsevier (Amsterdam, The Netherlands), 2020.
Figure 4. Mechanical–hydraulic wind energy conversion system. Reproduced with permission from [81], Elsevier (Amsterdam, The Netherlands), 2020.
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Figure 5. Hybrid wind–wave systems with OBs: (a) OBs installed on a floating platform. Reproduced with permission from [93], Elsevier (Amsterdam, The Netherlands), 2021. (b) OBs installed on a bottom-fixed platform. Reproduced with permission from [94], Elsevier (Amsterdam, The Netherlands), 2024.
Figure 5. Hybrid wind–wave systems with OBs: (a) OBs installed on a floating platform. Reproduced with permission from [93], Elsevier (Amsterdam, The Netherlands), 2021. (b) OBs installed on a bottom-fixed platform. Reproduced with permission from [94], Elsevier (Amsterdam, The Netherlands), 2024.
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Figure 6. The hydraulic PTO system of the OBs in hybrid wind–wave systems. Reproduced with permission from [63], Elsevier (Amsterdam, The Netherlands), 2022.
Figure 6. The hydraulic PTO system of the OBs in hybrid wind–wave systems. Reproduced with permission from [63], Elsevier (Amsterdam, The Netherlands), 2022.
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Figure 7. Direct-drive PTO systems in the OBs of hybrid wind–wave systems: (a) Direct mechanical-drive PTO system. (b) Direct electrical-drive PTO system.
Figure 7. Direct-drive PTO systems in the OBs of hybrid wind–wave systems: (a) Direct mechanical-drive PTO system. (b) Direct electrical-drive PTO system.
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Figure 8. Schematic of the OWC device.
Figure 8. Schematic of the OWC device.
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Figure 9. Conceptual drawings of hybrid wind–wave systems with OWCs: (a) Bottom-mounted type. Reproduced with permission from [108], Elsevier (Amsterdam, The Netherlands), 2021. (b) Floating type. Reproduced with permission from [109], Elsevier (Amsterdam, The Netherlands), 2024.
Figure 9. Conceptual drawings of hybrid wind–wave systems with OWCs: (a) Bottom-mounted type. Reproduced with permission from [108], Elsevier (Amsterdam, The Netherlands), 2021. (b) Floating type. Reproduced with permission from [109], Elsevier (Amsterdam, The Netherlands), 2024.
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Figure 10. Schematic drawing of an overtopping wave energy converter. Reproduced with permission from [111], Elsevier (Amsterdam, The Netherlands), 2017.
Figure 10. Schematic drawing of an overtopping wave energy converter. Reproduced with permission from [111], Elsevier (Amsterdam, The Netherlands), 2017.
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Figure 11. Schematic representation of hybrid wind–wave systems employing overtopping wave energy converters: (a) Versatile offshore platform. Reproduced with permission from [113], Elsevier (Amsterdam, The Netherlands), 2012. (b) Hybrid renewable energy system. Reproduced with permission from [40], Elsevier (Amsterdam, The Netherlands), 2017.
Figure 11. Schematic representation of hybrid wind–wave systems employing overtopping wave energy converters: (a) Versatile offshore platform. Reproduced with permission from [113], Elsevier (Amsterdam, The Netherlands), 2012. (b) Hybrid renewable energy system. Reproduced with permission from [40], Elsevier (Amsterdam, The Netherlands), 2017.
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Figure 12. Classification of the energy coupling technologies of existing hybrid wind–wave systems.
Figure 12. Classification of the energy coupling technologies of existing hybrid wind–wave systems.
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Figure 13. Configuration of AC coupling schemes.
Figure 13. Configuration of AC coupling schemes.
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Figure 14. Schematic representation of back-to-back PWM converters integrated into a hybrid wind–wave system. Reproduced with permission from [75], Elsevier (Amsterdam, The Netherlands), 2019.
Figure 14. Schematic representation of back-to-back PWM converters integrated into a hybrid wind–wave system. Reproduced with permission from [75], Elsevier (Amsterdam, The Netherlands), 2019.
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Figure 15. Configuration of DC coupling schemes.
Figure 15. Configuration of DC coupling schemes.
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Figure 16. Configuration of hydraulic coupling schemes.
Figure 16. Configuration of hydraulic coupling schemes.
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Figure 17. Schematic representation of W2P. Reproduced with permission from [125], Elsevier (Amsterdam, The Netherlands), 2019.
Figure 17. Schematic representation of W2P. Reproduced with permission from [125], Elsevier (Amsterdam, The Netherlands), 2019.
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Figure 18. Schematic representation of the hybrid wind–wave system in a single-generator scheme.
Figure 18. Schematic representation of the hybrid wind–wave system in a single-generator scheme.
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Figure 19. Percentages of the different wave energy conversion schemes and different PTO systems of OBs from 2012 to 2023: (a) percentages of different wave energy conversion schemes used; (b) percentages of the different PTO systems of OBs.
Figure 19. Percentages of the different wave energy conversion schemes and different PTO systems of OBs from 2012 to 2023: (a) percentages of different wave energy conversion schemes used; (b) percentages of the different PTO systems of OBs.
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Table 1. Representative hybrid wind–wave systems worldwide from 2010 to 2023.
Table 1. Representative hybrid wind–wave systems worldwide from 2010 to 2023.
YearInventorWind Conversion SchemeWave Conversion Scheme
/PTO System		Energy Coupling SchemeCapacity
2010Pelagic Power AS [72]Mechanical–electricalOBs/hydraulic PTOElectrical coupling10 MW
2010Green Ocean Energy [71]Mechanical–electricalOBs/hydraulic PTOElectrical coupling600 kW
2011Principle Power Inc [74]Mechanical–electricalOBs/hydraulic PTOElectrical coupling7 MW
2012Wave Star AS [89]Mechanical–electricalOBs/hydraulic PTOElectrical coupling600 kW
2012Fiaschi et al. [113]Mechanical–electricalOvertopping/electrical PTOElectrical coupling50 kW
2013Shi et al. [126]Mechanical–hydraulicOBs/hydraulic PTOHydraulic coupling15 MW
2014Liu et al. [131]Mechanical–electricalOBs/direct-drive PTOElectrical coupling500 W
2015Kim et al. [132]Mechanical–electricalOWCs/electrical PTOElectrical coupling10 MW
2016Chen et al. [125]Mechanical–electricalOBs/hydraulic PTOHydraulic coupling100 MW
2017Moschos et al. [40]Mechanical–electricalOvertopping/electrical PTOElectrical coupling500 kW
2017Chen et al. [66]Mechanical–electricalOBs/direct-drive PTOElectrical coupling5 kW
2018Floating Power Plant [133]Mechanical–electricalOWCs/electrical PTOElectrical coupling7 MW
2019Sarmiento et al. [134]Mechanical–electricalOWCs/electrical PTOElectrical coupling8 MW
2020Zhu et al. [135]Mechanical–electricalOWCs/electrical PTOElectrical coupling10 kW
2021Si et al. [93] Mechanical–electricalOBs/hydraulic PTOElectrical coupling4.7 MW
2021Aboutalebi et al. [136]Mechanical–electricalOWCs/electrical PTOElectrical coupling7 MW
2022Wang et al. [63]Mechanical–hydraulicOBs/hydraulic PTOHydraulic coupling20 KW
2023Zhang et al. [137]Mechanical–hydraulicOBs/hydraulic PTOHydraulic coupling50 KW
Table 2. Comparison between two wind energy conversion schemes.
Table 2. Comparison between two wind energy conversion schemes.
Evaluation IndexesMechanical–ElectricalMechanical–Hydraulic
System volumeLargeCompact
Numbers of componentsManyFew
Energy conversion times3 times3 times
Control difficultyComplexSimple [79]
ReliabilityLower [139]Higher
Transmission efficiencylowerHigher [140]
Economic costsHigher [141]Lower
Technological maturityMatureImmature
Table 4. Comparison between AC coupling and DC coupling.
Table 4. Comparison between AC coupling and DC coupling.
Evaluation IndexesAC CouplingDC Coupling
System structureSimpleComplex
Control difficultySimpleDifficult
ReliabilityLower [152]Higher [153]
Innovation spaceLargeLarge
ExpandabilityFiniteStrong [154]
Fault ride-though capabilityLowStrong [155]
Table 5. Comparison between hydraulic coupling and electrical coupling.
Table 5. Comparison between hydraulic coupling and electrical coupling.
Evaluation IndexesElectrical CouplingHydraulic Coupling
System structureComplexSimple
Storage elementMechanical storage of batteryAccumulator
AdaptabilityLowerStronger [157]
Transmission efficiencyLower [158]Higher [123]
Innovation spaceLargeLarge
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Wang, B.; Sun, Z.; Zhao, Y.; Li, Z.; Zhang, B.; Xu, J.; Qian, P.; Zhang, D. The Energy Conversion and Coupling Technologies of Hybrid Wind–Wave Power Generation Systems: A Technological Review. Energies 2024, 17, 1853. https://doi.org/10.3390/en17081853

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Wang B, Sun Z, Zhao Y, Li Z, Zhang B, Xu J, Qian P, Zhang D. The Energy Conversion and Coupling Technologies of Hybrid Wind–Wave Power Generation Systems: A Technological Review. Energies. 2024; 17(8):1853. https://doi.org/10.3390/en17081853

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Wang, Bohan, Zhiwei Sun, Yuanyuan Zhao, Zhiyan Li, Bohai Zhang, Jiken Xu, Peng Qian, and Dahai Zhang. 2024. "The Energy Conversion and Coupling Technologies of Hybrid Wind–Wave Power Generation Systems: A Technological Review" Energies 17, no. 8: 1853. https://doi.org/10.3390/en17081853

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