Статті в журналах: "Point absorber technology"

1

Khasawneh, Mohammad A., and Mohammed F. Daqaq. "Internally-resonant broadband point wave energy absorber." Energy Conversion and Management 247 (November 2021): 114751. http://dx.doi.org/10.1016/j.enconman.2021.114751.

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Hogan, R. E., and R. D. Skocypec. "Analysis of Catalytically Enhanced Solar Absorption Chemical Reactors: Part I—Basic Concepts and Numerical Model Description." Journal of Solar Energy Engineering 114, no. 2 (May 1, 1992): 106–11. http://dx.doi.org/10.1115/1.2929987.

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A detailed numerical model is presented for high-temperature, catalytically enhanced, solar absorption chemical reactors. In these reactors, concentrated solar energy is volumetrically absorbed throughout a porous absorber matrix impregnated with a catalyst. The catalyst promotes heterogeneous reactions with fluid-phase reactant species flowing through the absorber. This paper presents a description of a numerical model and the basic concepts of reactor operation. The numerical model of the absorber includes solar and infrared radiation, heterogeneous chemical reactions, conduction in the solid phase, and convection between the fluid and solid phases. The model is nonlinear primarily due to both the radiative transfer and the heterogeneous chemistry occurring in the absorber. The nonlinear two-point boundary value problem is solved using superposition with orthonormalization and an adaptive solution point scheme. This technique preserves accuracy throughout the domain. The model can be modified for other chemical reactions and can be simplified to model volumetric air-heating receivers.

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3

Alamian, Rezvan, Rouzbeh Shafaghat, and Mohammad Reza Safaei. "Multi-Objective Optimization of a Pitch Point Absorber Wave Energy Converter." Water 11, no. 5 (May 9, 2019): 969. http://dx.doi.org/10.3390/w11050969.

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In this paper, a pitch point absorber wave energy converter (WEC) is selected in order to be optimized for the wave characteristics of the Caspian Sea. The optimization process is a multi-objective optimization. For achieving the optimal WEC, mean absorbed power should be maximized while the construction cost should be minimized. The submerged surface area of the WEC is selected as a cost parameter. The amount of mean absorbed power depends on the installation site and also the shape of the WEC. For optimizing the shape of the WEC, various shapes are considered which are categorized into three different sections. A multi-objective genetic algorithm is used for optimization of the model, and the NEMOH software is used to simulate the wave-body interaction. The results show that the bottom flat and upside chamfered geometry with X:Y ratio of 10:1 is the best geometry for the desired application. Comparing the results from the final optimized shape with the optimized basic parallelepipedic hull shape reveals that much more extractable power can be achieved with less cost.

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Geehan, Genevieve, Ritika Ritika, and Coen Winchester. "Impact of Nanofluids and Specific Frequency Absorbers in Parabolic Trough Collector Solar Furnaces." PAM Review Energy Science & Technology 5 (May 31, 2018): 89–103. http://dx.doi.org/10.5130/pamr.v5i0.1502.

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This meta-study aims to identify methods of optimising the efficiency of upcoming parabolic trough collector (PTC) solar furnace technology by analysing thermodynamic properties of both solar absorbers: SiC, Pyromark 2500, Polychromic Al-AlN and C54-TiSi2 nanoparticles; and heat transfer nanofluids: SiO2, TiO2, Al2O3, Cu and Al2O3-Cu with a 50:50 ratio. The thermodynamic properties investigated are energy absorbance and emittance, melting point, thermal conductivity and viscosity. Our study revealed that the optimal transfer fluid is the hybrid nanofluid Al2O3-Cu with a 50:50 ratio and a 1-2% volume fraction in an ethylene glycol base. The optimal solar absorber for use in combination with this nanofluid was found to be polychromic Al-AlN cerment absorber.

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5

Guo, Bingyong, Tianyao Wang, Siya Jin, Shunli Duan, Kunde Yang, and Yaming Zhao. "A Review of Point Absorber Wave Energy Converters." Journal of Marine Science and Engineering 10, no. 10 (October 19, 2022): 1534. http://dx.doi.org/10.3390/jmse10101534.

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There are more than thousands of concepts for harvesting wave energy, and wave energy converters (WECs) are diverse in operating principles, design geometries and deployment manners, leading to misconvergence in WEC technologies. Among numerous WEC devices, the point absorber wave energy converter (PAWEC) concept is one of the simplest, most broad-based and most promising concepts that has been investigated intensively all over the world. However, there are only a few reviews focusing on PAWECs, and the dynamical advancement of PAWECs merits an up-to-date review. This review aims to provide a critical overview of the state of the art in PAWEC development, comparing and contrasting various PAWEC devices and discussing recent research and development efforts and perspectives of PAWECs in terms of prototyping, hydrodynamic modelling, power take-off mechanism and control.

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6

A., Elakkiya, Radha Sankararajan, Sreeja B.S., and Manikandan E. "Modified I-shaped hexa-band near perfect terahertz metamaterial absorber." Circuit World 46, no. 4 (July 16, 2020): 281–84. http://dx.doi.org/10.1108/cw-11-2019-0155.

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Purpose A novel and simple six-band metamaterial absorber is proposed in the terahertz region, which is composed of an I-shaped absorber and circular ring with four gaps and a continuous metal ground plane separated by only 0.125 mm polyimide dielectric substrate. Initially, I-shaped resonator gives three bands at 0.4, 0.468 and 0.4928 THz with the absorptivity of 99.3%, 97.9% and 99.1%, respectively. The purpose of this paper is to improve the number of bands, for which the authors added the circular ring with four gaps, so the simulated metamaterial absorber exhibited six absorption peaks at 0.3392, 0.3528, 0.3968, 0.4676, 0.4768 and 0.492 THz, with the absorption rate of 91.4%, 94.2%, 94.9%, 90.3%, 77.5% and 97.4%, respectively. The surface current distribution and angle independence are explained for all the six frequencies which are used to analyze the absorption mechanism clearly. Structure maximum uses the squares and circles, so it will make the fabrication easy. The multiband absorbers obtained here have potential applications in many engineering technology, thermal radiation, material detection and imaging and optoelectronic areas. Design/methodology/approach This paper presents the design of the six-band metamaterial absorber which is from the I-shaped resonator and circular ring with four gaps and the metallic ground plane separated by the 0.125 polyimide dielectric substrate. The absorber exhibited six absorption peaks at 0.3392, 0.3528, 0.3968, 0.4676, 0.4768 and 0.492 THz, with the absorption rate of 91.4%, 94.2%, 94.9%, 90.3%, 77.5% and 97.4%, respectively. From the fabrication point of view, the proposed six-band metamaterial absorber has a very simple geometrical structure, and it is very easy to be fabricated. Findings The authors present a new and simple design of six-band absorber based on an I-shaped absorber and circular ring with four gaps and a metallic ground plane separated by a polyimide layer having the thickness of 0.125 mm. Six different resonance absorption peaks are found at 0.3392, 0.3528, 0.3968, 0.4676 , 0.4768 and 0.492 THz. Surface current distribution and angle independence plot have been studied to understand the absorption behavior of the designed terahertz metamaterial absorber. Originality/value The multiband absorbers obtained here have potential applications in many engineering technology, thermal radiation, material detection, security, sensors, imaging and optoelectronic areas.

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7

Xu, Pengfei, Chenbo Han, Tao Lv, and Hongxia Cheng. "Underwater Absorber for a Remotely Operated Vehicle." Journal of Marine Science and Engineering 10, no. 4 (April 1, 2022): 485. http://dx.doi.org/10.3390/jmse10040485.

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Fixed-point underwater hovering is a key technology for the reliable operation of a remotely operated vehicle in the ocean to inspect the surfaces of a variety of underwater structures, such as ports and offshore wind power facilities. This study proposes an underwater wall absorber that can be used in remotely operated vehicles. First, we explain the working principle of the underwater absorber. Second, we analyze the main factors affecting its adsorption performance by using numerical simulations. Finally, we show the results of a tested prototype of the proposed absorber, whose performance was consistent with the results of numerical calculations. The proposed absorber may have important technical prospects for use in remotely operated underwater vehicles.

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8

Pierart, Fabián G., Joaquín Fernandez, Juan Olivos, Roman Gabl, and Thomas Davey. "Numerical Investigation of the Scaling Effects for a Point Absorber." Water 14, no. 14 (July 7, 2022): 2156. http://dx.doi.org/10.3390/w14142156.

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In order to design and evaluate the behaviour of a numerically optimised wave energy converter (WEC), a recommended procedure is to initially study small scale models in controlled laboratory conditions and then progress further up until the full-scale is reached. At any point, an important step is the correct selection of the wave theory to model the dynamical behaviour of the WEC. Most authors recommend the selection of a wave theory based on dimensional parameters, which usually does not consider the model scale. In this work, the scale effects for a point absorber are studied based on numerical simulations for three different regular waves conditions. Furthermore, three different wave theories are used to simulate two scales 1:1 and 1:50. The WEC-wave interaction is modelled by using a numerical wave tank implemented in ANSYS-Fluent with a floating object representing the WEC. Results show that the normalised difference between 1:1 and 1:50 models, keeping the same wave theory fluctuate between 30% and 58% of the WEC heave motion and that a wrong selection of the wave theory can lead to differences up to 138% for the same variable. It is also found that the limits for the use of wave theories depends on the particular model and that the range of applicability of different theories can be extended.

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9

Sun, Ke, Yang Yi, Xiongbo Zheng, Lin Cui, Chuankai Zhao, Mingyao Liu, and Xiang Rao. "Experimental investigation of semi-submersible platform combined with point-absorber array." Energy Conversion and Management 245 (October 2021): 114623. http://dx.doi.org/10.1016/j.enconman.2021.114623.

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10

Quartier, Nicolas, Pablo Ropero-Giralda, José M. Domínguez, Vasiliki Stratigaki, and Peter Troch. "Influence of the Drag Force on the Average Absorbed Power of Heaving Wave Energy Converters Using Smoothed Particle Hydrodynamics." Water 13, no. 3 (February 2, 2021): 384. http://dx.doi.org/10.3390/w13030384.

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In this paper, we investigated how the added mass, the hydrodynamic damping and the drag coefficient of a Wave Energy Converter (WEC) can be calculated using DualSPHysics. DualSPHysics is a software application that applies the Smoothed Particle Hydrodynamics (SPH) method, a Lagrangian meshless method used in a growing range of applications within the field of Computational Fluid Dynamics (CFD). Furthermore, the effect of the drag force on the WEC’s motion and average absorbed power is analyzed. Particularly under controlled conditions and in the resonance region, the drag force becomes significant and can greatly reduce the average absorbed power of a heaving point absorber. Once the drag coefficient has been determined, it is used in a modified equation of motion in the frequency domain, taking into account the effect of the drag force. Three different methods were compared for the calculation of the average absorbed power: linear potential flow theory, linear potential flow theory modified to take the drag force into account and DualSPHysics. This comparison showed the considerable effect of the drag force in the resonance region. Calculations of the drag coefficient were carried out for three point absorber WECs: one spherical WEC and two cylindrical WECs. Simulations in regular waves were performed for one cylindrical WEC with two different power take-off (PTO) systems: a linear damping and a Coulomb damping PTO system. The Coulomb damping PTO system was added in the numerical coupling between DualSPHysics and Project Chrono. Furthermore, we considered the optimal PTO system damping coefficient taking the effect of the drag force into account.

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11

Papini, Guglielmo, Francisco Javier Dores Piuma, Nicolás Faedo, John V. Ringwood, and Giuliana Mattiazzo. "Nonlinear Model Reduction by Moment-Matching for a Point Absorber Wave Energy Conversion System." Journal of Marine Science and Engineering 10, no. 5 (May 12, 2022): 656. http://dx.doi.org/10.3390/jmse10050656.

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This paper presents a data-driven model reduction by moment-matching approach to construct control-oriented models for a point absorber device. The methodology chosen and developed generates models which are input-to-state linear, with any nonlinear behaviour confined to the output map. Such a map is the result of a data-driven approximation procedure, where the so-called moment of the point absorber system is estimated via a least-squares procedure. The resulting control-oriented model can inherently preserve steady-state properties of the target WEC system for a user-defined class of input signals of interest, with the computation only dependent upon a suitably defined set of input-output data.

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12

Jakobsen, M. M., Scott Beatty, G. Iglesias, and M. M. Kramer. "Characterization of loads on a hemispherical point absorber wave energy converter." International Journal of Marine Energy 13 (April 2016): 1–15. http://dx.doi.org/10.1016/j.ijome.2016.01.003.

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13

Vervaet, Timothy, Vasiliki Stratigaki, Brecht De Backer, Kurt Stockman, Marc Vantorre, and Peter Troch. "Experimental Modelling of Point-Absorber Wave Energy Converter Arrays: A Comprehensive Review, Identification of Research Gaps and Design of the WECfarm Setup." Journal of Marine Science and Engineering 10, no. 8 (August 2, 2022): 1062. http://dx.doi.org/10.3390/jmse10081062.

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Commercial wave energy exploitation will be realised by placing multiple wave energy converters (WECs) in an array configuration. A point-absorber WEC consists of a floating or submerged body to capture wave energy from different wave directions. This point-absorber WEC acts as an efficient wave absorber that is also an efficient wave generator. Optimising the WEC array layout to obtain constructive interference within the WEC array is theoretically beneficial, whereas for wind farms, it is only important to avoid destructive interference within an array of wind turbines due to wake effects. Moreover, the WEC array layout should be optimised simultaneously with the applied control strategy. This article provides a literature review on the state of the art in physical modelling of point-absorber WEC arrays and the identification of research gaps. To cover the scientific gap of experimental data necessary for the validation of recently developed (nonlinear) numerical models for WEC arrays, Ghent University has introduced the “WECfarm” project. The identified research gaps are translated into design requirements for the “WECfarm” WEC array setup and test matrix. This article presents the design of the “WECfarm” experimental setup, consisting of an array of five generic heaving point-absorber WECs. The WECs are equipped with a permanent magnet synchronous motor (PMSM), addressing the need for WEC array tests with an accurate and actively controllable power take-off (PTO). The WEC array control and data acquisition are realised with a Speedgoat Performance real-time target machine, offering the possibility to implement advanced WEC array control strategies in the MATLAB-Simulink model. Wave basin testing includes long- and short-crested waves and extreme wave conditions, representing real sea conditions. Within the “WECfarm” project, two experimental campaigns were performed at the Aalborg University wave basin: (a) a testing of the first WEC in April 2021 and (b) a testing of a two-WEC array in February 2022. An experimental campaign with a five-WEC array is under preparation at the moment of writing.

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Zhang, Xianxiong, Bin Li, Zhenwei Hu, Jiang Deng, Panpan Xiao, and Mingsheng Chen. "Research on Size Optimization of Wave Energy Converters Based on a Floating Wind-Wave Combined Power Generation Platform." Energies 15, no. 22 (November 18, 2022): 8681. http://dx.doi.org/10.3390/en15228681.

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Wind energy and wave energy often co-exist in offshore waters, which have the potential and development advantages of combined utilization. Therefore, the combined utilization of wind and waves has become a research hotspot in the field of marine renewable energy. Against this background, this study analyses a novel integrated wind-wave power generation platform combining a semi-submersible floating wind turbine foundation and a point absorber wave energy converter (WEC), with emphasis on the size optimization of the WEC. Based on the engineering toolset software ANSYS-AQWA, numerical simulation is carried out to study the influence of different point absorber sizes on the hydrodynamic characteristics and wave energy conversion efficiency of the integrated power generation platform. The well-proven CFD software STAR CCM+ is used to modify the heaving viscosity damping of the point absorber to study the influence of fluid viscosity on the response of the point absorber. Based on this, the multi-body coupled time-domain model of the integrated power generation platform is established, and the performance of the integrated power generation platform is evaluated from two aspects, including the motion characteristics and wave energy conversion efficiency, which provides an important reference for the design and optimization of the floating wind-wave power generation platform.

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15

Wu, Jinming. "Geometry Optimization of Heaving Axisymmetric Point Absorbers under Parametrical Constraints in Irregular Waves." Journal of Marine Science and Engineering 9, no. 10 (October 16, 2021): 1136. http://dx.doi.org/10.3390/jmse9101136.

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The objective of this work is to identify the maximum absorbed power and optimal buoy geometry of a heaving axisymmetric point absorber for a given cost in different sea states. The cost of the wave energy converter is estimated as proportional to the displaced volume of the buoy, and the buoy geometry is described by the radius-to-draft ratio. A conservative wave-height-dependent motion constraint is introduced to prevent the buoy from jumping out of the free surface of waves. The constrained optimization problem is solved by a two-nested-loops method, within which a core fundamental optimization process employs the MATLAB function fmincon. Results show that the pretension of the mooring system should be as low as possible. Except for very small energy periods, the stiffness of both the power take-off and mooring system should also be as low as possible. A buoy with a small radius-to-draft ratio can absorb more power, but at the price of working in more energetic seas and oscillating at larger amplitudes. In addition, the method to choose the optimal buoy geometry at different sea states is provided.

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16

Previsic, Mirko, Anantha Karthikeyan, and Jeff Scruggs. "A Comparative Study of Model Predictive Control and Optimal Causal Control for Heaving Point Absorbers." Journal of Marine Science and Engineering 9, no. 8 (July 27, 2021): 805. http://dx.doi.org/10.3390/jmse9080805.

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Efforts by various researchers in recent years to design simple causal control laws that can be applied to WEC devices suggest that these controllers can yield similar levels of energy output as those of more complex non-causal controllers. However, most studies were established without adequately considering device and power conversion system constraints which are relevant design drivers from a cost and economic point of view. It is therefore imperative to understand the benefits of MPC compared to causal control from a performance and constraint handling perspective. In this paper, we compare linear MPC to a casual controller that incorporates constraint handling to benchmark its performance on a one DoF heaving point absorber in a range of wave conditions. Our analysis demonstrates that MPC provides significant performance advantages compared to an optimized causal controller, particularly if significant constraints on device motion and/or forces are imposed. We further demonstrate that distinct control performance regions can be established that correlate well with classical point absorber and volumetric limits of the wave energy conversion device.

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17

Götz, Maximilian, Norbert Osterthun, Kai Gehrke, Martin Vehse, and Carsten Agert. "Ultrathin Nano-Absorbers in Photovoltaics: Prospects and Innovative Applications." Coatings 10, no. 3 (February 29, 2020): 218. http://dx.doi.org/10.3390/coatings10030218.

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Approaching the first terawatt of installations, photovoltaics (PV) are about to become the major source of electric power until the mid-century. The technology has proven to be long lasting and very versatile and today PV modules can be found in numerous applications. This is a great success of the entire community, but taking future growth for granted might be dangerous. Scientists have recently started to call for accelerated innovation and cost reduction. Here, we show how ultrathin absorber layers, only a few nanometers in thickness, together with strong light confinement can be used to address new applications for photovoltaics. We review the basics of this new type of solar cell and point out the requirements to the absorber layer material by optical simulation. Furthermore, we discuss innovative applications, which make use of the unique optical properties of the nano absorber solar cell architecture, such as spectrally selective PV and switchable photovoltaic windows.

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18

Huang, Zhen Wei, Rui Duo Yin, Wen Jun Zhu, Wen Xin Shen, and Shen Ge. "Research on the Online Verification Instrument for Diaphragm Gas Meter." Applied Mechanics and Materials 457-458 (October 2013): 1189–94. http://dx.doi.org/10.4028/www.scientific.net/amm.457-458.1189.

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A novel online verification instrument for diaphragm gas meter based on positive displacement principle is proposed. Through an in-depth research on online verification technology, a dedicated wave absorber is designed to eliminate the effect of pressure pulsation. The whole series of the online diaphragm gas meter verification in normal operation condition is realized by adopting fixed-point calibration and nonlinear correction technology. The experimental data shows that the uncertainty is within 0.5% and the ratio of the measurement range is reach to 100:1.

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19

Rava, Marcello, Panagiotis Dafnakis, Vittorio Martini, Giuseppe Giorgi, Vincenzo Orlando, Giuliana Mattiazzo, Giovanni Bracco, and Andrea Gulisano. "Low-Cost Heaving Single-Buoy Wave-Energy Point Absorber Optimization for Sardinia West Coast." Journal of Marine Science and Engineering 10, no. 3 (March 9, 2022): 397. http://dx.doi.org/10.3390/jmse10030397.

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This work presents the Water Energy Point Absorber (WEPA), which is a heaving single-buoy point absorber optimized for a specific site off the west coast of Sardinia Island. The aim of the study is to present the optimization process undertaken to identify the best configuration in terms of performance and cost. The optimization is carried out thanks to a simulation tool developed in Matlab-Simulink environment and verified through to the commercial software Orcaflex. Simulations are performed in the time domain with the installation site’s waves as input. The hydrodynamics parameters are computed thanks to the commercial software Ansys Aqwa and given to the model as input. The yearly energy production is computed as output for each configuration. Several parametric analyses are performed to identify the optimal Power Take Off (PTO) and buoy size. Among the main findings, it shall be mentioned that the PTO-rated torque has a strong influence on the energy production, higher PTO-rated torque proved to have better performance. The optimal hull size is strictly related to the incoming waves, and for the given site the smaller hulls are performing better than larger ones. The hull height, hull mass and hull draft have little impact on productivity. Finally, a comprehensive techno–economic analysis is performed, showing that the best configuration can be identified only after a detailed feasibility study and rigorous cost analysis.

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20

Gureev, A. O., and Y. G. Pikulin. "Determination of values of the solution flow rate and temperature in carbon dioxide absorption process." Izvestiya MGTU MAMI 8, no. 2-3 (May 20, 2014): 91–96. http://dx.doi.org/10.17816/2074-0530-67591.

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Steady growth in world energy prices requires finding the optimal conditions for the processes of chemical technology. Results of testing of previously prepared a mathematical model of the process of purification of industrial gases from carbon dioxide. Shows the dependence of the absorption capacity and the amount of absorbed CO2 by the fluid flow. Proved that no need for the use of the liquid flow rate is similar flooding regime of absorber, since at some point the increase of liquid flow ceases to have a significant impact on the overall absorption capacity of the solution. Also shown is the possibility of reducing the flow of solution in industrial environments, which allows to obtain economic benefits from reduced energy consumption on the circulation of the solution and the gas purification process in general. The value of the temperature for maximum rate of chemisorption of carbon dioxide.

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Zheng, Xiongbo, Shuanghong Zhou, Yong Ma, and Lingling Wang. "Analytical Research on Energy Conversion Characteristic of a Kind of Point Absorber Wave Energy Device." Journal of Coastal Research 83, sp1 (May 4, 2019): 991. http://dx.doi.org/10.2112/si83-163.1.

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Demonte Gonzalez, Tania, Gordon G. Parker, Enrico Anderlini, and Wayne W. Weaver. "Sliding Mode Control of a Nonlinear Wave Energy Converter Model." Journal of Marine Science and Engineering 9, no. 9 (September 1, 2021): 951. http://dx.doi.org/10.3390/jmse9090951.

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The most accurate wave energy converter models for heaving point absorbers include nonlinearities, which increase as resonance is achieved to maximize the energy capture. Over the power production spectrum and within the physical limits of the devices, the efficiency of wave energy converters can be enhanced by employing a control scheme that accounts for these nonlinearities. This paper proposes a sliding mode control for a heaving point absorber that includes the nonlinear effects of the dynamic and static Froude-Krylov forces. The sliding mode controller tracks a reference velocity that matches the phase of the excitation force to ensure higher energy absorption. This control algorithm is tested in regular linear waves and is compared to a complex-conjugate control and a nonlinear variation of the complex-conjugate control. The results show that the sliding mode control successfully tracks the reference and keeps the device displacement bounded while absorbing more energy than the other control strategies. Furthermore, due to the robustness of the control law, it can also accommodate disturbances and uncertainties in the dynamic model of the wave energy converter.

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23

Adkins, Douglas R. "Design Considerations for Heat-Pipe Solar Receivers." Journal of Solar Energy Engineering 112, no. 3 (August 1, 1990): 169–76. http://dx.doi.org/10.1115/1.2930476.

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Heat pipes are being developed to transfer solar energy from the focal point of a parabolic dish concentrator to the working fluid of Stirling engines. With these receivers, concentrated solar energy that is absorbed on the concave surface of a dome is removed by the evaporation of liquid sodium on the convex side of the dome. Vaporized sodium then condenses on an engine’s heater tubes and transfers energy to the working fluid of the engine. The condensed sodium returns to the absorber surface where it is redistributed across the dome by the capillary action of a wick. Issues concerning the flow of sodium in a heat-pipe solar receiver are investigated in this paper. A comparison is made between various wick options, and general issues concerning the design of heat-pipe receivers are also discussed.

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Montoya, Dan, Elisabetta Tedeschi, Luca Castellini, and Tiago Martins. "Passive Model Predictive Control on a Two-Body Self-Referenced Point Absorber Wave Energy Converter." Energies 14, no. 6 (March 20, 2021): 1731. http://dx.doi.org/10.3390/en14061731.

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Wave energy is nowadays one of the most promising renewable energy sources; however, wave energy technology has not reached the fully-commercial stage, yet. One key aspect to achieve this goal is to identify an effective control strategy for each selected Wave Energy Converter (WEC), in order to extract the maximum energy from the waves, while respecting the physical constraints of the device. Model Predictive Control (MPC) can inherently satisfy these requirements. Generally, MPC is formulated as a quadratic programming problem with linear constraints (e.g., on position, speed and Power Take-Off (PTO) force). Since, in the most general case, this control technique requires bidirectional power flow between the PTO system and the grid, it has similar characteristics as reactive control. This means that, under some operating conditions, the energy losses may be equivalent, or even larger, than the energy yielded. As many WECs are designed to only allow unidirectional power flow, it is necessary to set nonlinear constraints. This makes the optimization problem significantly more expensive in terms of computational time. This work proposes two MPC control strategies applied to a two-body point absorber that address this issue from two different perspectives: (a) adapting the MPC formulation to passive loading strategy; and (b) adapting linear constraints in the MPC in order to only allow an unidirectional power flow. The results show that the two alternative proposals have similar performance in terms of computational time compared to the regular MPC and obtain considerably more power than the linear passive control, thus proving to be a good option for unidirectional PTO systems.

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Vervaet, Timothy, Vasiliki Stratigaki, Francesco Ferri, Louis De Beule, Hendrik Claerbout, Bono De Witte, Marc Vantorre, and Peter Troch. "Experimental Modeling of an Isolated WECfarm Real-Time Controllable Heaving Point Absorber Wave Energy Converter." Journal of Marine Science and Engineering 10, no. 10 (October 11, 2022): 1480. http://dx.doi.org/10.3390/jmse10101480.

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To offer point absorber wave energy converters (WECs) as a bankable product on the marine renewable energy market, multiple WECs will be installed together in an array configuration. The wave energy community (research and industrial) has identified the urgent need for available realistic and reliable data on WEC array tests in order to perform a better WEC array optimization approach and in order to validate recently developed (non-linear) numerical models. The `WECfarm’ project is initiated to cover this scientific gap on necessary experimental data. The `WECfarm’ experimental setup consists of an array of five generic heaving point-absorber WECs. The WECs are equipped with a permanent magnet synchronous motor (PMSM), addressing the need for WEC array tests with an accurate and actively controllable power take-off (PTO). The WEC array control and data acquisition are realized with a Speedgoat Performance real-time target machine, offering the possibility to implement advanced WEC array control strategies in the MATLAB-Simulink environment. The presented article describes the experimental setup, the performed tests and the results of the test campaign using a single, isolated `WECfarm’ WEC in April 2021 at the wave basin of Aalborg University (AAU), Denmark. A Coulomb and viscous friction model is determined to partly compensate for the drivetrain (motor, gearbox, rack and pinion) friction. A system identification (SID) approach is adopted considering the WEC system to be composed of two single input single output (SISO) models, the radiation and the excitation model. Radiation tests yield the intrinsic impedance. Excitation tests yield the excitation frequency response function. Adopting an impedance matching approach, the control parameters for the resistive and reactive controller are determined from the complex conjugate of the intrinsic impedance. Both controllers are tested for a selection of regular wave conditions. The performed experimental test campaign using an isolated `WECfarm’ WEC allows a full evaluation of the WEC design prior to extending the setup to five WECs. Within the `WECfarm’ project, an experimental campaign with a five-WEC array in the Coastal and Ocean Basin (COB) in Ostend, Belgium, is under preparation.

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Montoya Andrade, Dan-El, Antonio de la Villa Jaén, and Agustín García Santana. "Considering linear generator copper losses on model predictive control for a point absorber wave energy converter." Energy Conversion and Management 78 (February 2014): 173–83. http://dx.doi.org/10.1016/j.enconman.2013.10.037.

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Saadatnia, Zia, Ehsan Asadi, Hassan Askari, Ebrahim Esmailzadeh, and Hani E. Naguib. "A heaving point absorber-based triboelectric-electromagnetic wave energy harvester: An efficient approach toward blue energy." International Journal of Energy Research 42, no. 7 (February 28, 2018): 2431–47. http://dx.doi.org/10.1002/er.4024.

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Skene, David M., Nataliia Sergiienko, Boyin Ding, and Benjamin Cazzolato. "The Prospect of Combining a Point Absorber Wave Energy Converter with a Floating Offshore Wind Turbine." Energies 14, no. 21 (November 5, 2021): 7385. http://dx.doi.org/10.3390/en14217385.

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With recent advances in offshore floating wind and wave energy technology, questions have emerged as to whether the two technologies can be combined to reduce their overall levelised cost of energy. In this paper, the potential for combining a floating offshore wind turbine to a point absorbing wave energy converter is investigated. The focus of the investigation is how much power might be produced by a combined floating wind and wave energy converter system, and the resultant changes in motion of the floating wind platform. A model for the combined wave and wind system is developed which uses the standardised NREL OC3 5 MW spar type wind turbine and a cylindrical buoyant actuator (BA), which is attached to the spar via a generic wave power take-off system (modelled as a spring-damper system). Modelling is conducted in the frequency domain and the tests span a wide range of parameters, such as wave conditions, BA sizes, and power take-off coupling arrangements. It is found that the optimal (with respect to power production) BA size is a draft and radius of approximately 14 m. It is found that this BA can theoretically produce power in the range of 0.3 to 0.5 MW for waves with a significant wave height of 2 m, and has the potential to produce power greater or near to 1 MW for waves with a significant wave height of at least 3 m. However, it is also found that, in terms of the relative capture width, significantly smaller BAs are optimal, and that these smaller BA sizes less significantly alter the motion of the floating wind platform.

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Mujeeb, Mohammed Aman. "Effect of Temperature Variation on Oil in Oscillation of Mass/Load." International Journal for Research in Applied Science and Engineering Technology 9, no. 12 (December 31, 2021): 403–8. http://dx.doi.org/10.22214/ijraset.2021.39252.

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Abstract: In this investigation a model was made to replicate the working of a shock absorber and the liquid that is used in place of the hydraulic fluid was vegetable oil. Hydraulic fluid is composed of a mineral oil base stock [1]. The working of the model of a shock absorber was tested at different temperatures. It is studied that the relation between the temperature and the time taken by the load attached to the spring to stop oscillating and presented in graph. An optimum temperature, at which the time taken by the mass of 1.50 kilograms suspended in the vegetable oil to stop oscillating and it is the least mass used in the study. In addition to this, the freezing point of the vegetable oil will also be found. It is found in this study that the two variables that is temperature of the vegetable oil and the mass of 1.5 kilograms at rest is linear. Keywords: Temperature Variation, Oil, Oscillation, Mass, Load.

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30

Ropero-Giralda, Pablo, Alejandro J. C. Crespo, Ryan G. Coe, Bonaventura Tagliafierro, José M. Domínguez, Giorgio Bacelli, and Moncho Gómez-Gesteira. "Modelling a Heaving Point-Absorber with a Closed-Loop Control System Using the DualSPHysics Code." Energies 14, no. 3 (February 1, 2021): 760. http://dx.doi.org/10.3390/en14030760.

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The present work addresses the need for an efficient, versatile, accurate and open-source numerical tool to be used during the design stage of wave energy converters (WECs). The device considered here is the heaving point-absorber developed and tested by Sandia National Laboratories. The smoothed particle hydrodynamics (SPH) method, as implemented in DualSPHysics, is proposed since its meshless approach presents some important advantages when simulating floating devices. The dynamics of the power take-off system are also modelled by coupling DualSPHysics with the multi-physics library Project Chrono. A satisfactory matching between experimental and numerical results is obtained for: (i) the heave response of the device when forced via its actuator; (ii) the vertical forces acting on the fixed device under regular waves and; (iii) the heave response of the WEC under the action of both regular waves and the actuator force. This proves the ability of the numerical approach proposed to simulate accurately the fluid–structure interaction along with the WEC’s closed-loop control system. In addition, radiation models built from the experimental and WAMIT results are compared with DualSPHysics by plotting the intrinsic impedance in the frequency domain, showing that the SPH method can be also employed for system identification.

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Chen, Yih-Hang, Ming-Tien Shen, Hsuan Chang, and Chii-Dong Ho. "Control of Solvent-Based Post-Combustion Carbon Capture Process with Optimal Operation Conditions." Processes 7, no. 6 (June 12, 2019): 366. http://dx.doi.org/10.3390/pr7060366.

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Solvent-based post-combustion carbon capture (PCC) is a mature and essential technology to solve the global warming problem. The high energy consuming issue and the flexible operation required by the power plants inquire about the development of effective control systems for PCC plants. This study proposes the optimal-based control approach that utilizes optimal set-point values for the quality controllers. The five optimal-based control schemes studied all employed L/G (liquid to gas ratio in absorber) as one quality control variable. Performance comparisons with a typical conventional control scheme are conducted employing a rate-based dynamic model for the MEA (monoethanolamine) solvent PCC process developed on a commercial process simulator. Compared to the typical control scheme, the optimal-based control schemes provide faster responses to the disturbance changes from the flue gas conditions and the set-point change of the CO2 capture efficiency, as well as better results in terms of IAEs (integral of absolute errors) of capture efficiency and reboiler heat duty during the stabilization period. LG-Tstr and LG-Tabs-Cascade are the best schemes. In addition to L/G, these two schemes employ the control of Tstr (the temperature of a stage of stripper) and a cascade control of Tabs (the temperature of a stage of absorber) (outer loop) and Tstr (inner loop), respectively.

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Gu, Yu Jiong, Li Jun Zhao, Jing Hua Huang, and Bing Bing Wang. "The Principle, Review and Prospect of Wave Energy Converter." Advanced Materials Research 347-353 (October 2011): 3744–49. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3744.

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Abstract: Being confronted with the severity of the energy and environment problems, the world attaches more and more importance to the potential of wave energy. Based on the necessity and feasibility of wave power development, the basic principles of wave energy converter are in this paper firstly. Then some kinds of WEC’s principle, merits and drawbacks, technology application are reviewed, such as OWC, raft, Tapchan, point absorber, Salter, pendulum. After that, wave energy developing conditions in some typical countries are recommended. After reviewing the features of various wave energy converters and WEC application examples in some countries, prospect and a few problems in wave energy utilizing are stated briefly.

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Wang, Daming, Daniel Conley, Martyn Hann, Keri Collins, Siya Jin, and Deborah Greaves. "Power output estimation of WEC with HF radar measured complex representative sea states." International Marine Energy Journal 5, no. 1 (June 8, 2022): 1–10. http://dx.doi.org/10.36688/imej.5.1-10.

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Wave tank model testing has been widely used to assess the performance of Wave Energy Converters (WEC) in different technology readiness levels (TRL). At early stage the use of simple wave conditions such as regular waves and parametric wave spectrum JONSWAP or Pierson-Moskowitz spectrum is acceptable. However at later stages there is a need to use site specific complex wave conditions representative of potential prototype deployment sites. In previous research, 10 different regrouping methods on HF radar measured wave spectrum were tested to find out the most representative sea states for tank testing. It has been shown that by using the K-means clustering technique, the characteristics of wave conditions can be well preserved. In order to assess the power capture performance of a typical WEC in these representative sea states, the RM3 point absorber has been simulated. By analysing how well the average power output predicted from different representative sea-state selection methods compares with the total power output prediction, it is shown that the non-directional wave spectrum K-means clustering method provides the most representative sea states and, for a point absorber, with a very accurate estimation of the total power output, which is not the case by using a traditional binning method. The importance of using the complex site-specific sea states rather than simplified parametric JONSWAP sea states to obtain the accurate total power estimation has also been shown.

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Lee, Jinkyu, Yondo Chun, Jiwon Kim, and Byounggun Park. "An Energy-Harvesting System Using MPPT at Shock Absorber for Electric Vehicles." Energies 14, no. 9 (April 29, 2021): 2552. http://dx.doi.org/10.3390/en14092552.

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This paper investigates an energy-harvesting system that uses of vibration energy at a shock absorber for electric vehicles. This system mainly comprises a linear electromagnetic generator and synchronous buck converter. To obtain the electrical energy through a linear electromagnetic generator, the perturb and observe maximum power point tracking (P&O MPPT) scheme is applied at the converter. The power converter circuit is designed with a diode rectifier and synchronous buck converter. The generated electric power is able to transmit to the battery and the damping force of the shock absorber is adjusted by the controlled current of generator. The linear electromagnetic generator was designed as a single phase eight-slot eight-pole tubular permanent magnet machine. The performance of the proposed energy-harvesting system was verified through simulations and experiments.

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35

Prasetyowati, Ane, Wisnu Broto, and Noor Suryaningsih. "LINEAR GENERATOR PROTOTYPE WITH VERTICAL CONFIGURATION OF SEA WAVE POWER PLANT." Spektra: Jurnal Fisika dan Aplikasinya 6, no. 3 (December 30, 2021): 185–200. http://dx.doi.org/10.21009/spektra.063.05.

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There are three types of potential energy sources in the sea: ocean wave energy, tidal energy, and ocean heat energy. Ocean wave energy is a source of considerable energy. Sea waves are an up and down movement of seawater where the energy of sea waves is generated through the effect of air pressure movement due to fluctuations in ocean wave movements. The Ocean Wave Power Plant can use ocean wave energy to convert it into electrical energy. A linear generator is a device that can convert the mechanical energy of linear motion into electrical energy. The application of the ocean wave energy conversion technology, a linear generator system is an electrical machine that functions to convert the mechanical energy of linear motion into electrical energy using the principle of electromagnetic induction. Wave Energy Converter (WEC) technology has been developed with various methods. From the various existing concepts and designs, in general, WEC technology can be classified into three main types, namely Attenuator (horizontal configuration), Point Absorber (linear configuration), Terminator (damping configuration).

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Berville, Charles, Florin Bode, and Cristiana Croitoru. "Numerical Simulation Investigation of a Double Skin Transpired Solar Air Collector." Applied Sciences 12, no. 1 (January 5, 2022): 520. http://dx.doi.org/10.3390/app12010520.

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Transpired solar collectors (TSC) are one of the most popular solar thermal technologies for building façades. TSC use solar energy to heat the absorber surface, which transmits thermal energy to the ambient air. A variant of TSC, namely, a double skin transpired solar collector (DSTSC), has been analyzed in this paper, thus providing guide values and a technical point of view for engineers, architects, and constructors when designing such transpired solar collectors. Three important parameters were addressed in this study through numerical simulation: the influence of a separation plate introduced in a TSC, turning it into a DSTSC; the air layer thickness influence on the performance of the collector; and the influence of the used absorber materials for the separation plate material. Greater heat exchange efficiency was noticed for the DSTSC at every imposed airflow rate compared with the TSC. Regarding the thickness of the collector, the efficiency gradually increased when increasing the solar collector thickness until it reached a value of 20 cm, though not varying significantly at a thickness of 30 cm.

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37

Wang, Xin, Daming Li, Yanqing Li, and Huamei Wang. "A Study on the Evaluation Method of Layout Effectiveness of Wave Energy Converter Array - An Example from Point Absorber Wave Energy Converter." Journal of Coastal Research 99, sp1 (May 14, 2020): 165. http://dx.doi.org/10.2112/si99-024.1.

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38

Dang, Tri Dung, Cong Binh Phan, and Kyoung Kwan Ahn. "Design and Investigation of a Novel Point Absorber on Performance Optimization Mechanism for Wave Energy Converter in Heave Mode." International Journal of Precision Engineering and Manufacturing-Green Technology 6, no. 3 (March 28, 2019): 477–88. http://dx.doi.org/10.1007/s40684-019-00065-w.

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Jalani, Muhamad Aiman, Mohd Rashdan Saad, Mohamad Faizal Abdullah, Mohd Azzeri Md Naiem, Mohd Norsyarizad Razali, Noh Zainal Abidin, and Mohd Rosdzimin Abdul Rahman. "A Statistical Analysis for Optimisation of a Hybrid BBDB-PA in Mantanani Island, Sabah." Journal of Marine Science and Engineering 11, no. 2 (February 9, 2023): 386. http://dx.doi.org/10.3390/jmse11020386.

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The hybrid form of wave energy converter (WEC) is a recent advancement in research concerning harvesting energy from the ocean. This study investigates the effect of size and position of the point absorber integrated with a backward bent duct buoy. The aim of this optimisation is to maximise the WEC-absorbed power and heave response amplitude operators (RAO) at a specific sea site. The optimisation process was applied based on the data collected over a one-year period about sea characteristics for a nearshore region of the Mantanani Island. We present a methodology for optimising the Hybrid BBDB-PA based on a statistical analysis and the hydrodynamics of the system in the frequency and time domain. We used the ANSYS/AQWA software for the hydrodynamic diffraction analysis, and the design of experiments method was applied through the statistical software to determine the optimised parameters. We found that the diameter and gap length between PA and BBDB were found to significantly influence two characteristics, namely, heave RAO and maximum power absorption of PA. This observation shows that the PA size was directly proportional to the performance because a higher diameter has more contact with the ocean’s wet surface area with the ocean and absorbed higher wave energy. Moreover, the gap length between the PA and BBDB was directly correlated with a wavelength, which followed the theoretical value for peak-to-trough length, where the maximum wave height occurs. Despite the condition parameter, we discovered that the WEC position and arrangement were responsible for the highest value of the power, regardless of the PA position used in the experiment. The results of this research provide recommendations for optimising the ocean energy harvesting in order to fully utilise ocean space for energy.

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Green, Brandon E., and Daniel G. MacDonald. "The Use of Numerical Modeling to Optimize a New Wave Energy Converter Technology." Marine Technology Society Journal 47, no. 4 (July 1, 2013): 151–63. http://dx.doi.org/10.4031/mtsj.47.4.7.

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AbstractA numerical model of a new point-absorber wave energy converter (WEC) technology was designed for simulation purposes using Python. The governing equations were defined to take into account the relevant forces on the buoy in an ideal wave environment as well as any opposing forces due to damping, the power take-off (PTO) mechanism, and alternator. These equations of motion were solved using a high-order iterative process to study the linear kinematics of the buoy, the behavior of the PTO, and the associated power output in an ideal ocean wave environment. The model allows for the adjustment of relevant parameters to explore the behavior of the WEC and optimize system efficiency depending on the wave conditions. The numerical model was designed to run single simulations for a specified time interval; however, an optimization routine was implemented to optimize the mechanical parameters that greatly affect power output. The optimization portion of the model was implemented to study the response of the virtual WEC to a variety of input conditions pertaining to the buoy, PTO, and wave dynamics. This paper explains the development of the prototype WEC and the associated numerical model, in addition to evaluating the response of the WEC to a variety of input conditions. The output of the numerical model is discussed for the associated wave field used for simulation purposes. The design and implementation of the numerical model provides insight into changes in design components to maximize system power output and efficiency. The results of the numerical model and examples of data output for specific input conditions are investigated.

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Li, Yang, Lei Huang, Peiwen Tan, Minshuo Chen, and Junquan Chen. "Resonance Control Based on Hydrodynamic Analysis for Underwater Direct Drive Wave Energy Converter." Journal of Marine Science and Engineering 9, no. 11 (October 27, 2021): 1192. http://dx.doi.org/10.3390/jmse9111192.

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Wave energy has great prospect among many forms of marine renewable energy for its high density and storage. This paper proposes an underwater direct drive wave energy converter (UDDWEC), which is composed of a submerged point absorbing buoy and a linear-rotating axial flux permanent magnetic generator (LR-AFPMG). In addition, a maximum energy capture control strategy, resonance control, is derived for UDDWEC, based on small amplitude oscillation and hydrodynamic analysis. The proposed control strategy assumes the availability of sea condition such as wave height and period. This control strategy has three main characteristics. Firstly, this control strategy is derived based on hydrodynamic analysis of the submerged point absorber. Added mass, radiation damping and other hydrodynamic parameters are obtained to participate in UDDWEC dynamic model. Secondly, a LR-AFPMG is applied as power take-off device to realize energy conversion, which can improve the power density. Thirdly, small amplitude oscillation can be changed into long stroke rotary motion through the LR-AFPMG. The reliability and effectiveness of the proposed control strategy are assessed at various operation conditions for a heaving system and the validity for the UDDWEC is verified.

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Hamilton, Andrew, François Cazenave, Dominic Forbush, Ryan G. Coe, and Giorgio Bacelli. "The MBARI-WEC: a power source for ocean sensing." Journal of Ocean Engineering and Marine Energy 7, no. 2 (May 2021): 189–200. http://dx.doi.org/10.1007/s40722-021-00197-9.

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AbstractInterest in wave energy converters to provide autonomous power to various ocean-bound systems, such as autonomous underwater vehicles, sensor systems, and even aquaculture farms, has grown in recent years. The Monterey Bay Aquarium Research Institute has developed and deployed a small two-body point absorber wave energy device suitable to such needs. This paper provides a description of the system to support future open-source access to the device and further the general development of similar wave energy systems. Additionally, to support future control design and system modification efforts, a set of hydrodynamic models are presented and cross-compared. To test the viability of using a linear frequency-domain admittance model for controller tuning, the linear model is compared against four WEC-Sim models of increasing complexity. The linear frequency-domain model is found to be generally adequate for capturing system dynamics, as the model agreement is good and the degree of nonlinearity introduced in the WEC-Sim models is generally less than 2.5%.

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43

Karayaka, Hayrettin Bora, Yi-Hsiang Yu, and Eduard Muljadi. "Investigations into Balancing Peak-to-Average Power Ratio and Mean Power Extraction for a Two-Body Point-Absorber Wave Energy Converter." Energies 14, no. 12 (June 11, 2021): 3489. http://dx.doi.org/10.3390/en14123489.

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Анотація:

The power harnessed by wave energy converters (WECs) in oceans is highly variable and, therefore, has a high peak-to-average power (PTAP) ratio. To minimize the cost of a WEC power take off (PTO) system, it is desirable to reduce the PTAP ratio while maximizing the mean power extracted by WECs. The important issue of how PTAP ratio reduction measures (such as adding an inertia element) can affect the mean power extracted in a reference model has not been thoroughly addressed in the literature. To investigate this correlation, this study focuses on the integration of the U.S. Department of Energy’s Reference Model 3, a two-body point absorber, with a slider-crank WEC for linear-to-rotational conversion. In the first phase of this study, a full-scale numerical model was developed that predicts how PTO system parameters, along with an advanced control algorithm, can potentially affect the proposed WEC’s PTAP ratio as well as the mean power extracted. In the second phase, an appropriate scaled-down model was developed, and extracted power results were successfully validated against the full-scale model. Finally, numerical and hardware-in-the-loop (HIL) simulations based on the scaled-down model were designed and conducted to optimize or make trade-offs between the operational performance and PTAP ratio. The initial results with numerical and HIL simulations reveal that gear ratio, crank radius, and generator parameters substantially impact the PTAP ratio and mean power extracted.

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Midhat, Yousif Fateh, and Issam Mohammed Ali Aljubury. "Experimental Evaluation of Thermohydraulic Performance of Tubular Solar Air Heater." International Journal of Renewable Energy Development 12, no. 1 (September 26, 2022): 66–76. http://dx.doi.org/10.14710/ijred.2023.45312.

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The thermohydraulic performance of a new design solar air heater (SAH) design was examined experimentally in this paper as a trial to improve the flat-plate SAH’s efficiency. A flat-plate solar air heater (FPSAH) and a jacketed tubular solar air heater (JTSAH) having similar dimensions were constructed to compare their thermal performance efficiencies. A band of Aluminum jacketed tubes were arranged side by side in parallel to the airflow direction to form the absorber of a jacketed tubular solar air heater (JTSAH). The experiments were accomplished at three mass flow rates (MFR)s: 0.011 kg/s. 0.033 kg/s, and 0.055 kg/s. Results revealed that the maximum temperature difference was obtained from JTSAH at 38°C in comparison to 32°C from the FPSAH at MFR of 0.011 kg/s. The thermal losses from the upper glass cover of the JTSAH were less than the same losses at the FPSAH due to the reduced absorber and glass temperatures of the JTSAH. The gained power was higher at the JTSAH than the FPSAH. At the JTSAH, at 0.055 kg/s MFR, the maximum average thermal efficiency obtained was 81%, and the maximum average thermos-hydraulic efficiency obtained was 75.61 %. It is noted that increasing the MFR increases the thermal efficiency, also, its optimum value rises the thermos-hydraulic efficiency to a specific optimum point. The pressure drop increases with the MFR and JTSAH compared to the FPSAH

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45

Castellucci, Valeria, and Erland Strömstedt. "Sea level variability in the Swedish Exclusive Economic Zone and adjacent seawaters: influence on a point absorbing wave energy converter." Ocean Science 15, no. 6 (November 19, 2019): 1517–29. http://dx.doi.org/10.5194/os-15-1517-2019.

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Abstract. Low-frequency sea level variability can be a critical factor for several wave energy converter (WEC) systems, for instance, linear systems with a limited stroke length. Consequently, when investigating suitable areas for deployment of those WEC systems, sea level variability should be taken into account. In order to facilitate wave energy developers finding the most suitable areas for wave energy park installations, this paper describes a study that gives them additional information by exploring the annual and monthly variability of the sea level in the Baltic Sea and adjacent seawaters, with a focus on the Swedish Exclusive Economic Zone. Overall, 10 years of reanalysis data from the Copernicus project have been used to conduct this investigation. The results are presented by means of maps showing the maximum range and the standard deviation of the sea level with a horizontal spatial resolution of about 1 km. A case study illustrates how the results can be used by the WEC developers to limit the energy absorption loss of their devices due to sea level variation. Depending on the WEC technology one wants to examine, the results lead to different conclusions. For the Uppsala point absorber L12 and the sea state considered in the case study, the most suitable sites where to deploy WEC parks from a sea level variation viewpoint are found in the Gotland basins and in the Bothnian Sea, where the energy loss due to sea level variations is negligible.

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46

Haider, Ali S., Ted K. A. Brekken, and Alan McCall. "Real-Time Nonlinear Model Predictive Controller for Multiple Degrees of Freedom Wave Energy Converters with Non-Ideal Power Take-Off." Journal of Marine Science and Engineering 9, no. 8 (August 18, 2021): 890. http://dx.doi.org/10.3390/jmse9080890.

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An increase in wave energy converter (WEC) efficiency requires not only consideration of the nonlinear effects in the WEC dynamics and the power take-off (PTO) mechanisms, but also more integrated treatment of the whole system, i.e., the buoy dynamics, the PTO system, and the control strategy. It results in an optimization formulation that has a nonquadratic and nonstandard cost functional. This article presents the application of real-time nonlinear model predictive controller (NMPC) to two degrees of freedom point absorber type WEC with highly nonlinear PTO characteristics. The nonlinear effects, such as the fluid viscous drag, are also included in the plant dynamics. The controller is implemented on a real-time target machine, and the WEC device is emulated in real-time using the WECSIM toolbox. The results for the successful performance of the design are presented for irregular waves under linear and nonlinear hydrodynamic conditions.

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Amaechi, Chiemela Victor, Facheng Wang, and Jianqiao Ye. "Mathematical Modelling of Bonded Marine Hoses for Single Point Mooring (SPM) Systems, with Catenary Anchor Leg Mooring (CALM) Buoy Application—A Review." Journal of Marine Science and Engineering 9, no. 11 (October 26, 2021): 1179. http://dx.doi.org/10.3390/jmse9111179.

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The application of mathematical analysis has been an essential tool applied on Catenary Anchor Leg Mooring (CALM) buoys, Wave Energy Converters (WEC), point absorber buoys, and various single point mooring (SPM) systems. This enables having mathematical models for bonded marine hoses on SPM systems with application with CALM buoys, which are obviously a requisite for the techno-economic design and operation of these floating structures. Hose models (HM) and mooring models (MM) are utilized on a variety of applications such as SPARs, Semisubmersibles, WECs and CALM buoys. CALM buoys are an application of SPM systems. The goal of this review is to address the subject of marine hoses from mathematical modeling and operational views. To correctly reproduce the behavior of bonded marine hoses, including nonlinear dynamics, and to study their performance, accurate mathematical models are required. The paper gives an overview of the statics and dynamics of offshore/marine hoses. The reviews on marine hose behavior are conducted based on theoretical, numerical, and experimental investigations. The review also covers challenges encountered in hose installation, connection, and hang-off operations. State-of-the-art, developments and recent innovations in mooring applications for SURP (subsea umbilicals, risers, and pipelines) are presented. Finally, this study details the relevant materials that are utilized in hoses and mooring implementations. Some conclusions and recommendations are presented based on this review.

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Cai, Yuanzhen, Milad Bazli, Asanka P. Basnayake, Martin Veidt, and Michael T. Heitzmann. "Composite Springs for Mooring Tensioners: A Systematic Review of Material Selection, Fatigue Performance, Manufacturing, and Applications." Journal of Marine Science and Engineering 10, no. 9 (September 12, 2022): 1286. http://dx.doi.org/10.3390/jmse10091286.

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Ocean energy is an underutilized renewable energy source compared with hydropower and wind power. Therefore, the development of economical and efficient wave energy converters (WECs) is important and crucial for offshore power generation. The mooring tensioner is a critical device that can be used in point-absorber-type WECs, semisubmersible floats for oil and gas drilling, and floating wind turbines. A mooring tensioner is a system used to create, reduce, or maintain tension within the mooring lines by applying a force to the mooring line. Composite springs as mooring tensioners have several advantages compared to metal springs, such as corrosion resistance, high specific strain energy, appropriate fatigue performance, and the ability to flexibly adjust the spring constant without changing the overall dimensions. This paper reviews in detail the fatigue performance, seawater durability, and manufacturing methods of different composite materials as well as the current and potential applications of composites springs. In addition, recommendations for future research and opportunities for composite mooring tensioners are presented.

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Barbarelli, Silvio, Mario Amelio, Teresa Castiglione, Gaetano Florio, and Nino Michele Scornaienchi. "Design and analysis of a new wave energy converter based on a point absorber and a hydraulic system harvesting energy from waves near the shore in calm seas." International Journal of Energy Research 45, no. 1 (September 2, 2020): 661–90. http://dx.doi.org/10.1002/er.5799.

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50

Amini, Erfan, Danial Golbaz, Rojin Asadi, Mahdieh Nasiri, Oğuzhan Ceylan, Meysam Majidi Nezhad, and Mehdi Neshat. "A Comparative Study of Metaheuristic Algorithms for Wave Energy Converter Power Take-Off Optimisation: A Case Study for Eastern Australia." Journal of Marine Science and Engineering 9, no. 5 (May 1, 2021): 490. http://dx.doi.org/10.3390/jmse9050490.

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One of the most encouraging sorts of renewable energy is ocean wave energy. In spite of a large number of investigations in this field during the last decade, wave energy technologies are recognised as neither mature nor broadly commercialised compared to other renewable energy technologies. In this paper, we develop and optimise Power Take-off (PTO) configurations of a well-known wave energy converter (WEC) called a point absorber. This WEC is a fully submerged buoy with three tethers, which was proposed and developed by Carnegie Clean Energy Company in Australia. Optimising the WEC’s PTO parameters is a challenging engineering problem due to the high dimensionality and complexity of the search space. This research compares the performance of five state-of-the-art metaheuristics (including Covariance Matrix Adaptation Evolution Strategy, Gray Wolf optimiser, Harris Hawks optimisation, and Grasshopper Optimisation Algorithm) based on the real wave scenario in Sydney sea state. The experimental achievements show that the Multiverse optimisation (MVO) algorithm performs better than the other metaheuristics applied in this work.

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