Marine Renewable Energy, 2nd Edition

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600	Submit
Journal of Marine Science and Engineering jmse	2.7	4.4	2013	16.9 Days	CHF 2600	Submit
Processes processes	2.8	5.1	2013	14.4 Days	CHF 2400	Submit
Sustainability sustainability	3.3	6.8	2009	20 Days	CHF 2400	Submit
Inventions inventions	2.1	4.8	2016	21.2 Days	CHF 1800	Submit

20 pages, 6721 KiB

Open AccessArticle

Conceptual Design and Dynamic Analysis of a Wind–Wave Energy Converter with a Mass-Adjustable Buoy

by Yifeng Shi, Jiahuan Lin, Zexin Zhuge, Rongye Zheng and Jun Zhang

J. Mar. Sci. Eng. 2024, 12(8), 1460; https://doi.org/10.3390/jmse12081460 - 22 Aug 2024

Viewed by 631

To reduce the levelized cost of energy (LCOE) for offshore wind turbines, a novel wind–wave energy converter (WWEC) with a mass-adjustable buoy is designed. To analyze the impact of buoy mass variations on the system, a coupled comprehensive numerical model is established to [...] Read more.

To reduce the levelized cost of energy (LCOE) for offshore wind turbines, a novel wind–wave energy converter (WWEC) with a mass-adjustable buoy is designed. To analyze the impact of buoy mass variations on the system, a coupled comprehensive numerical model is established to simulate the aerodynamics of the turbine and the hydrodynamics of the platform and buoy. It is found that the occurrence of the buoy out of water significantly reduces the output power. Adjusting the buoy’s mass with suitable strategy can prevent the impact of slamming loads and improve the power output. The mass adjustment strategy is determined based on the output power of the wave energy converter under regular wave conditions. It is found that the mass adjustment strategy can significantly enhance the output power of combined system. The buoy does not move out of the water under the extreme conditions, which avoids the impact of slamming loads on system stability. Moreover, mass-adjustable buoys can reduce the risk of mooring line failure compare to a wind turbine without a buoy. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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33 pages, 4010 KiB

Open AccessReview

A Review of Available Solutions for Implementation of Small–Medium Combined Heat and Power (CHP) Systems

by Cătălina Dobre, Mihnea Costin and Mihaela Constantin

Inventions 2024, 9(4), 82; https://doi.org/10.3390/inventions9040082 - 19 Jul 2024

Cited by 2 | Viewed by 1843

Abstract

The transition towards a sustainable and renewable energy future is essential to mitigate climate change and reduce greenhouse gas emissions. Small–medium combined heat and power (CHP) systems are increasingly popular for distributed energy generation, as they offer improved energy efficiency and reduced emissions [...] Read more.

The transition towards a sustainable and renewable energy future is essential to mitigate climate change and reduce greenhouse gas emissions. Small–medium combined heat and power (CHP) systems are increasingly popular for distributed energy generation, as they offer improved energy efficiency and reduced emissions compared to traditional power generation systems. This article reviews recent research articles related to small–medium CHP systems, including their role in renewable energy systems, use of biofuels, steam injection, diagnostics, and carbon capture. Throughout the research, the high potential of coastal regions has been observed and studied as a solid base for the later development of CHP systems. Based on the reviewed literature, the highest potential solutions are proposed to be further investigated as an efficient, economical solution for generating electricity and heat for various small-scale applications. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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26 pages, 11114 KiB

Open AccessArticle

Spatial and Temporal Variability of Ocean Thermal Energy Resource of the Pacific Islands

by Jessica Borges Posterari, Takuji Waseda, Takeshi Yasunaga and Yasuyuki Ikegami

Energies 2024, 17(11), 2766; https://doi.org/10.3390/en17112766 - 5 Jun 2024

Viewed by 770

Abstract

A lack of natural resources drives the oil dependency in Pacific Island Countries and Territories (PICTs), hampering energy security and imposing high electricity tariffs in the region. Nevertheless, the Western Equatorial Pacific is known for its large Sea Surface Temperature (SST) and deep-sea [...] Read more.

A lack of natural resources drives the oil dependency in Pacific Island Countries and Territories (PICTs), hampering energy security and imposing high electricity tariffs in the region. Nevertheless, the Western Equatorial Pacific is known for its large Sea Surface Temperature (SST) and deep-sea water (DSW) temperature difference favorable for harvesting thermal energy. In this study, we selected 18 PICTs in the western Equatorial Pacific to estimate Annual Energy Production (AEP) for a 1 MW class Ocean Thermal Energy Conversion (OTEC) plant. We combined the DSW temperature from the mean in situ Argo profiles and 1 km resolution satellite SST data to estimate the thermal energy resource resolving the fine features of the island coastline. Furthermore, the twenty-year-long SST dataset was used to analyze the SST variability. The analysis showed that Equatorial islands and Southern islands have the highest inter-annual variability due to El Nino Southern Oscillation (ENSO). The power density varied from 0.26 to 0.32 W/m² among the islands, with the lowest values found for the southernmost islands near the South Equatorial Countercurrent. Islands within the South Equatorial Current, Equatorial Undercurrent, and North Equatorial Countercurrent showed the highest values for both power density and gross power. Considering a 1 MW class OTEC plant, Annual Energy Production (AEP) in 2022 varied from 7 GWh to 8 GWh, with relatively low variability among islands near the Equator and in low latitudes. Considering the three variables, AEP, SST variability, and distance from the shore, Nauru is a potential candidate for OTEC, with a net power of 1.14 MW within 1 km from the shore. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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17 pages, 5834 KiB

Open AccessArticle

Study on the Flame Transition Characteristics of a Gas Turbine Combustor

by Mingmin Chen, Li Wang, Xinbo Huang, Minwei Zhao, Lingwei Zeng, Hongtao Zheng and Fuquan Deng

J. Mar. Sci. Eng. 2024, 12(5), 719; https://doi.org/10.3390/jmse12050719 - 26 Apr 2024

Cited by 1 | Viewed by 1094

Abstract

Gas turbines are widely used as important equipment for electricity generation on islands and offshore platforms. During the operation of a gas turbine, the flame shape in the combustion chamber undergoes variations in response to changes in parameters such as gas turbine load, [...] Read more.

Gas turbines are widely used as important equipment for electricity generation on islands and offshore platforms. During the operation of a gas turbine, the flame shape in the combustion chamber undergoes variations in response to changes in parameters such as gas turbine load, fuel distribution, and burner structure. These alterations in flame shape exert influence on combustion instability, emissions, and load characteristics. This study explores the variations in flame transition, emissions, and operating parameters among three distinct center stage structures: namely, the non-premix center stage (NPCS), premix center stage (PCS), and enhanced premix center stage (PCSE). The investigation is conducted using a heavy-duty gas turbine hybrid burner on a full temperature, full pressure, and full-size single burner experimental bench. Simultaneously, a multi-parameter numerical simulation regarding the influence of the central fuel split on flame shape analysis was conducted using the PCS burner under the design point for a more in-depth understanding of the mechanisms and for influencing factors associated with flame transition. The findings indicate that variations in flame transition loads among different central stage structures: for the NPCS burner, the transition occurs between 45% and 50% load; for the PCS burners, it takes place between 60% and 65% load; for the PCSE burners, it shifts between 55% and 60% load. Additionally, a reduction in NO_x emissions is observed during the flame transition process. Furthermore, it was found that decreasing the central stage fuel results in a decline in flame angle for the same burner structure. As the central stage fuel diminishes to a specific value, the flame shape undergoes a sudden change. Further reduction in central stage fuel does not significantly affect the flame shape and temperature distribution. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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20 pages, 2427 KiB

Open AccessArticle

A Generalized Empirical Model for Velocity Deficit and Turbulent Intensity in Tidal Turbine Wake Accounting for the Effect of Rotor-Diameter-to-Depth Ratio

by Kabir Bashir Shariff and Sylvain S. Guillou

Energies 2024, 17(9), 2065; https://doi.org/10.3390/en17092065 - 26 Apr 2024

Cited by 2 | Viewed by 765

Abstract

Commercial scale tidal stream turbines (TST) are expected to be deployed in shallow water where the depth varies from 1.5 to 3 turbine diameters. In this study, numerical simulation is conducted at realistic hydrodynamic conditions of potential tidal sites using the stationary actuator [...] Read more.

Commercial scale tidal stream turbines (TST) are expected to be deployed in shallow water where the depth varies from 1.5 to 3 turbine diameters. In this study, numerical simulation is conducted at realistic hydrodynamic conditions of potential tidal sites using the stationary actuator disc method at ambient turbulence varying from 5% to 20%, a range of rotor realistic rotor thrust coefficient from 0.64 to 0.98 and a rotor-diameter-to-depth ratio of 20% to 60%. The result shows that the TST wake is affected by the rotor-diameter-to-depth ratio, ambient turbulence, and thrust coefficient. The new empirical model is in accordance with the numerical simulation of a full-scale turbine and is validated with the TST experiment at different rotor-diameter-to-depth ratios with reasonable results in the far wake. This low computational model can benefit the investigation of tidal turbine parks at different configurations where the far wake is pertinent. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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16 pages, 3394 KiB

Open AccessArticle

Impact of Oxygen Content on Flame Dynamics in a Non-Premixed Gas Turbine Model Combustor

by Mingmin Chen, Xinbo Huang, Zhaokun Wang, Hongtao Zheng and Fuquan Deng

J. Mar. Sci. Eng. 2024, 12(4), 621; https://doi.org/10.3390/jmse12040621 - 4 Apr 2024

Viewed by 1138

Abstract

In this study, large eddy simulation (LES) was used to investigate the dynamic characteristics of diffusion flames in a swirl combustion chamber at an oxygen content of 11–23 wt% and temperature of 770 K. The proper orthogonal decomposition (POD) method was employed to [...] Read more.

In this study, large eddy simulation (LES) was used to investigate the dynamic characteristics of diffusion flames in a swirl combustion chamber at an oxygen content of 11–23 wt% and temperature of 770 K. The proper orthogonal decomposition (POD) method was employed to obtain flame dynamic modes. The results indicate that oxygen content has a significant impact on the downstream flow and flame combustion characteristics of the swirl combustion chamber. With oxygen content increasing, the size of the recirculation zone is reduced, and the flame field fluctuations are intensified. The pressure and heat release fluctuations under different oxygen contents were analyzed using frequency spectrum analysis. Finally, the flame modes were analyzed using the POD method, and it was found that the coherent structures are asymmetric relative to the local coordinate system. At an oxygen content of 11 wt%, they exhibit larger coherent structures, while at an oxygen content of 23 wt%, they exhibit numerous turbulent structures. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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18 pages, 9752 KiB

Open AccessArticle

A Composite Super-Twisting Sliding Mode Approach for Platform Motion Suppression and Power Regulation of Floating Offshore Wind Turbine

by Wenxiang Yang, Yaozhen Han, Ronglin Ma, Mingdong Hou and Guang Yang

J. Mar. Sci. Eng. 2023, 11(12), 2318; https://doi.org/10.3390/jmse11122318 - 7 Dec 2023

Cited by 1 | Viewed by 1186

Abstract

The floating platform motion of an offshore wind turbine system can exacerbate output power fluctuations and increase fatigue loads. This paper proposes a new scheme based on a fast second-order sliding mode (SOSM) control and an adaptive super-twisting extended state observer to suppress [...] Read more.

The floating platform motion of an offshore wind turbine system can exacerbate output power fluctuations and increase fatigue loads. This paper proposes a new scheme based on a fast second-order sliding mode (SOSM) control and an adaptive super-twisting extended state observer to suppress the platform motion and power fluctuation. Firstly, an affine nonlinear model of the floating wind turbine pitch system is constructed. Then, a fast SOSM pitch control law is adopted to adjust the blade pitch angle, and a new adaptive super-twisting extended state observer is constructed to achieve total disturbance observation. Finally, simulations are conducted under two cases of wind and wave conditions based on FAST (fatigue, aerodynamics, structures, and turbulence) and MATLAB/Simulink. Compared with the traditional proportional integral (PI) control scheme and standard super-twisting control scheme, the platform roll under the proposed scheme is reduced by 13% and 4%, and pitch is reduced by 16% and 3% in Case 1. Correspondingly, the roll is reduced by 9% and 15%, and pitch is reduced by 7% and 1% in Case 2. For the tower top pitch and yaw moment, load reductions of 7% and 3% or more are achievable compared with those under the PI control scheme. It is indicated that the proposed scheme is more effective in suppressing floating platform motion, stabilizing output power of the wind turbine system, and reducing tower loads. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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14 pages, 4248 KiB

Open AccessArticle

Test and Analysis of the Heat Exchanger for Small Ocean Thermal Energy Power Generation Devices

by Xiao Wu, Xiangnan Wang and Bingzhen Wang

Energies 2023, 16(22), 7559; https://doi.org/10.3390/en16227559 - 13 Nov 2023

Viewed by 1121

Abstract

The application of ocean thermal energy conversion is an effective method to extend underwater vehicles’ running times and operating ranges, and the solid–liquid phase transition of the phase change material (PCM) in the heat exchanger is a key process for underwater vehicles to [...] Read more.

The application of ocean thermal energy conversion is an effective method to extend underwater vehicles’ running times and operating ranges, and the solid–liquid phase transition of the phase change material (PCM) in the heat exchanger is a key process for underwater vehicles to collect ocean thermal energy. This study proposes a heat exchanger structure for a small-size thermal energy power generation device and establishes the heat transfer model for the heat exchanger. Simulations were conducted considering convective heat transfer, and the obtained results demonstrated the feasibility of the designed structure. A prototype of the heat exchanger was developed, and physical experiments were conducted to validate the performance of the prototype. The results show that the melting process of the heat exchanger can be completed within 6 to 12 h, the solidification process can be completed within 3 to 7 h, and the heat transfer time decreases with the increase in temperature difference, verifying the compatibility with the underwater vehicles’ working patterns. Moreover, the heat exchanger could theoretically extend their lifetime. The results can provide a reference for the structural design and optimization of the heat exchanger for small ocean thermal energy power generation devices in the future. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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17 pages, 3846 KiB

Open AccessArticle

Optimal Design and Performance Analysis of a Hybrid System Combining a Semi-Submersible Wind Platform and Point Absorbers

by Binzhen Zhou, Jianjian Hu, Qi Zhang, Lei Wang, Fengmei Jing and Maurizio Collu

J. Mar. Sci. Eng. 2023, 11(6), 1190; https://doi.org/10.3390/jmse11061190 - 8 Jun 2023

Cited by 4 | Viewed by 1677

Abstract

Integrating point absorber wave energy converters (PAWECs) and an offshore floating wind platform provide a cost-effective way of joint wind and wave energy exploitation. However, the coupled dynamics of the complicated hybrid system and its influence on power performance are not well understood. [...] Read more.

Integrating point absorber wave energy converters (PAWECs) and an offshore floating wind platform provide a cost-effective way of joint wind and wave energy exploitation. However, the coupled dynamics of the complicated hybrid system and its influence on power performance are not well understood. Here, a frequency-domain-coupled hydrodynamics, considering the constraints and the power output through the relative motion between the PAWECs and the semi-submersible platform, is introduced to optimize the size, power take-off damping, and layout of the PAWECs. Results show that the annual wave power generation of a PAWEC can be improved by 30% using a 90° conical or a hemispherical bottom instead of a flat bottom. Additionally, while letting the PAWECs protrude out the sides of the triangular frame of the platform by a distance of 1.5 times the PAWEC radius, the total power generation can be improved by up to 18.2% without increasing the motion response of the platform. The PAWECs can reduce the resonant heave motion of the platform due to the power take-off damping force. This study provides a reference for the synergistic use of wave and wind energy. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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20 pages, 23210 KiB

Open AccessArticle

Experimental Investigation of Flow-Induced Motion and Energy Conversion for Two Rigidly Coupled Triangular Prisms Arranged in Tandem

by Jijian Lian, Zhichuan Wu, Shuai Yao, Xiang Yan, Xiaoqun Wang, Zhaolin Jia, Yan Long, Nan Shao, Defeng Yang and Xinyi Li

Energies 2022, 15(21), 8190; https://doi.org/10.3390/en15218190 - 2 Nov 2022

Cited by 3 | Viewed by 1621

Abstract

A series of experimental tests on flow-induced motion (FIM) and energy conversion of two rigidly coupled triangular prisms (TRCTP) in tandem arrangement were conducted in a recirculating water channel with the constant oscillation mass m_osc. The incoming flow velocity covered the [...] Read more.

A series of experimental tests on flow-induced motion (FIM) and energy conversion of two rigidly coupled triangular prisms (TRCTP) in tandem arrangement were conducted in a recirculating water channel with the constant oscillation mass m_osc. The incoming flow velocity covered the range of 0.395 m/s ≤ U ≤ 1.438 m/s, corresponding to the Reynolds number range of 3.45 × 10⁴ ≤ Re ≤ 1.25 × 10⁵. The upstream and downstream triangular prisms with a width of 0.1 m and length of 0.9 m were connected by two rectangular endplates. Seven stiffness (1000 N/m ≤ K ≤ 2400 N/m), five load resistances (8 Ω ≤ R_L ≤ 23 Ω), and five gap ratios (1 ≤ L/D ≤ 4) were selected as the parameters, and the FIM responses and energy conversion of TRCTP in tandem were analyzed and discussed to illustrate the effects. The experimental results indicate that the “sharp jump” phenomenon may appear at L/D = 2 and L/D = 3 significantly, with substantially increasing amplitude and decreasing oscillation frequency. The maximum amplitude ratio in the experiments is A*_Max = 2.24, which appears after the “sharp jump” phenomenon at L/D = 3. In the present tests, the optimal active power P_harn = 21.04 W appears at L/D = 4 (U_r = 12.25, K = 2000 N/m, R_L = 8 Ω), corresponding to the energy conversion efficiency η_harn = 4.67%. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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20 pages, 4892 KiB

Open AccessArticle

Experimental Proof-of-Concept of a Hybrid Wave Energy Converter Based on Oscillating Water Column and Overtopping Mechanisms

by Irene Simonetti, Andrea Esposito and Lorenzo Cappietti

Energies 2022, 15(21), 8065; https://doi.org/10.3390/en15218065 - 30 Oct 2022

Cited by 8 | Viewed by 2552

Abstract

This paper presents the results of laboratory tests on a hybrid wave energy converter concept, the O²WC (Oscillating-Overtopping Water Column) device. The proposed device aims at providing an alternative to the classical OWC concept, storing part of the wave energy of [...] Read more.

This paper presents the results of laboratory tests on a hybrid wave energy converter concept, the O²WC (Oscillating-Overtopping Water Column) device. The proposed device aims at providing an alternative to the classical OWC concept, storing part of the wave energy of the highly energetic sea states in a second chamber at atmospheric pressure, through overtopping phenomena. In this way, the maximum airflow rate and air pressure in the OWC chamber are reduced, possibly aiding the safe functioning of the air turbine, and allowing to exploit the excess of energy instead of dissipating it through by-pass valves. The performance of the device is investigated under different incident wave conditions, for different design parameters. The height of the overtopping threshold from the second chamber of the device which allows to maximize the performance has been selected. Results show that the decrease of the primary conversion efficiency of the OWC component of the device caused by the decreased air pressure in the OWC chamber can be partially compensated by the additional energy stored in the overtopping chamber of the O²WC device. Overall, the studied O²WC device has capture width ratio values ranging between 0.3 and 0.7. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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20 pages, 11112 KiB

Open AccessArticle

A Numerical Performance Analysis of a Rim-Driven Turbine in Real Flow Conditions

by Ke Song and Yuchi Kang

J. Mar. Sci. Eng. 2022, 10(9), 1185; https://doi.org/10.3390/jmse10091185 - 25 Aug 2022

Cited by 7 | Viewed by 2297

Abstract

The tidal turbines represent a new frontier for extracting energy from tides source. Despite the technology being mature, new solutions aimed at improving performance, reliability with reduced environmental impact, manufacturing and installation costs are currently under investigation. The Rim-driven turbine (abbreviated as RDT) [...] Read more.

The tidal turbines represent a new frontier for extracting energy from tides source. Despite the technology being mature, new solutions aimed at improving performance, reliability with reduced environmental impact, manufacturing and installation costs are currently under investigation. The Rim-driven turbine (abbreviated as RDT) was recently proposed. A RDT resembles a ducted turbine (abbreviated as DT), as both contain blades and a duct. The present study aims at investigating the detail performance and flow field of a RDT in a real flow based on the China Zhaitang Island’s tidal current data. To show the difference between the RDT and DT, simulations are also performed on the corresponding DT. It is found that the power and thrust for the two configurations exhibit time-periodic behavior that is consistent with the wave frequency. At axial flow, the fluctuation amplitude on the power and thrust increase with the increase of tip speed ratio. The RDT has higher power output when operating at lower tip speed ratio and has a potential reduction in flow resistance and disturbance with respect to the DT. At yawed flow, the fluctuation amplitude on the power and thrust decrease with the increase of yaw angle. The RDT has less capable of compensating the effect of yawed inflow in reducing the power than the DT at larger yaw angle. In addition, the power and thrust generates micro-amplitude fluctuation integrated into the main waveform, which the frequency is consistent with the turbine rotation frequency. The wake characteristics analysis reveals that the yawed flow field is more turbulent, and the two configurations suffer strong unsteady flow separation along the whole span. Strong interactions are observed between the rotor’s main wake and the duct’s upper wake. The yaw angle primarily determines the downstream wake deflection direction and significantly changes the wake shape and vortex structures. Meanwhile, the wake flow is found to recover more quickly at larger yaw angle. Besides, due to the open-center of RDT, a part free-stream flow is allowed to travel through and forms an obvious high velocity zone. The presence of open-center of RDT has avoided the low velocity zone, improved the wake structure and accelerated wakes recover, which seems to give an advantageous effect in operating a RDT. Full article

(This article belongs to the Topic Marine Renewable Energy, 2nd Edition)

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