Study on Wave Power Generator Using Flexible Piezoelectric Device

Author(s):  
Hidemi Mutsuda ◽  
Kenta Kawakami ◽  
Masato Hirata ◽  
Yasuaki Doi ◽  
Yoshikazu Tanaka

We have developed a new wave power generator using flexible piezoelectric device (FPED) which is a hydro-electric ocean energy unit designed to convert renewable energy harnessed from ocean energy into usable electricity. In our previous works, the FPED consisting of piezo-electric polymer film (PVDF) is a way of harvesting electrical energy from the ocean power, e.g. tide, current, wave, breaking wave and vortex. The concept of this study is that the existing coastal and ocean structures (i.e. breakwater, submerged obstacle, reef in shallow water and submerged plate in deep water) are utilized as a wave power generator attached with the FPED to make a safety and disaster prevention. We examined the usefulness and electric performance of the FPED excited by waves in experiments.

Author(s):  
Hidemi Mutsuda ◽  
Ryuta Watanabe ◽  
Shota Azuma ◽  
Yoshikazu Tanaka ◽  
Yasuaki Doi

We have developed a way of harvesting electrical energy from ocean power, e.g. tide, current wave, breaking wave and vortex, using a Flexible PiezoElectric Device (FPED) consisting of polyvinyledene fluoride (PVDF) and elastic material such as rubber, silicon and resin. The proposed FPED has a multi-layered structure with a distance δ between FPEDs located away from centerline of the FPED. When the FPED can be easily deformed by ocean power, the PVDF laminated in the FPED can be expanded and compressed and then the internal strain energy can be stored in the FPED. The electric power is generated when the electric polarization occurs in the PVDF. In this study, we have proposed an ocean power generator of EFHAS (Elastic Floating unit with HAnging Structures) consisting of floating unit and hanging unit using the FPEDs to obtain electric power from ocean energy. We investigated a structure of the EFHAS and also examined characteristics of motion and electric performance of the EFHAS (1/50–1/75 scale model. We made clear that the EFHAS could be useful as ocean power generator.


Author(s):  
Hidemi Mutsuda ◽  
Kenta Kawakami ◽  
Takayuki Kurokawa ◽  
Yasuaki Doi ◽  
Yoshikazu Tanaka

We have developed a way of harvesting electrical energy from the ocean power, e.g. tide, current, wave, breaking wave and vortex, using a flexible piezoelectric device consisting of piezo-electric polymer film (PVDF), silicon and natural rubber. The flexible piezoelectric device (FPED) is a hydro-electric ocean energy converter designed to convert renewable energy harnessed from ocean energy into usable electricity. The basic concept generating electric power using FPED is to utilize fluid structure interaction, e.g. flattering, flapping and periodic bending, caused by ocean energy. The FPED deformed by kinetic energy of the ocean power stores elastic energy and also converts it to the electric energy. We carried out some experiments using wave tank and the water tunnel with a bluff body. We have confirmed the electricity generated by wave, current and vortex using the FPED. The developed FPED could be a new technology of harvesting electrical energy from the ocean power. A floating platform attached FPED could be coupled with an offshore wind turbine as a hybrid energy system in ocean space.


Author(s):  
Hidemi MUTSUDA ◽  
Kenta KAWAKAMI ◽  
Masato HIRATA ◽  
Yasuaki DOI ◽  
Yoshikazu TANAKA ◽  
...  

Author(s):  
S. Chiba ◽  
M. Waki ◽  
C. Jiang ◽  
K. Fujita

Abstract As industrialization, worldwide population growth, and improvements in the living standards in developing countries continue, demands for energy, food, and water, likewise surge. This in turn accelerates global warming, and its resultant extreme weather effects. Among the measures proposed to meet the growing energy demands, the use of renewable energy is gaining more and more attention. In particular, wave power generation is attracting a great deal of attention as an effective use of ocean energy. However, current wave generators are large and very expensive relative to their output. Furthermore, they cannot generate power efficiently with wave directivity, small amplitude waves and so on. For these reasons, widespread use is very limited. In order to solve these problems, this paper discusses the possibility of a recently developed wave power generator that uses a newly developed dielectric elastomer (DE) as a new way to harvest renewable energy. We also discuss the technical breakthrough of building a mega power generation system using DEs.


Author(s):  
Hidemi Mutsuda ◽  
Ryuta Watanabe ◽  
Masato Hirata ◽  
Yasuaki Doi ◽  
Yoshikazu Tanaka

The purpose of this study is to improve FPED (Flexible PiEzoelectric Device) we have developed. The FPED consisting of piezo-electric polymer film (PVDF) is a way of harvesting electrical energy from ocean power, e.g. tide, current, wave, breaking wave and vortex. We also propose an Elastic Floating unit with HAanging Structures (EFHAS) using FPED. The EFHAS consists of floating unit and hanging unit. In this study, we investigated electric performance of FPED and EFHAS and also modified internal structure of FPED to increase electrical efficiency. As a result, Electric performance is increasing with increasing number of PVDFs laminated in FPED. Multilayer type of FPED can rapidly increase electric efficiency. Electric power can be improved by FPED attached a bluff body with relative density. Electric performance of floating type for floating unit of EFHAS is better than that of submerged type. Distance L/λ = 0.4 between floaters of floating unit is suitable for highly electric performance. In hanging unit of EFHAS, it is possible to increase electric power per unit area with increasing number of stairs. In conclusion, we showed the EFHAS with the FPED could be useful for harvesting ocean wave energy.


2021 ◽  
Vol 11 (2) ◽  
pp. 429-436
Author(s):  
Widi Aribowo ◽  
Achmad Imam Agung ◽  
Subuh Isnur Haryudo ◽  
Syamsul Muarif

The need for electrical energy has increased every year. On the other hand, the largest power plants in Indonesia still use non-renewable energy sources such as coal and petroleum, while these non-renewable energy sources will eventually run out. To anticipate running out of this energy, a renewable energy source is needed. This existence will not run out even though it is consumed every day. Renewable energy that can be used for conversion into electrical energy in coastal areas is wave power.  The waves that always crash on the shoreline can be used to drive turbines. The turbine rotates due to the crashing waves connected to a DC generator. It will convert mechanical energy into electrical energy. The electrical energy generated by the DC generator is used to charge the battery. The purpose of this research is the know-how to design a wave power generator and to determine the performance. The experimental method is used in this study. In the results, the generator works optimally during the day with the resulting voltage of 10.6 V to 10.7 V with rotation speed of 623 Rpm to With 710 Rpm.


2021 ◽  
Vol 9 (5) ◽  
pp. 520
Author(s):  
Zhenyu Liu ◽  
Zhen Guo ◽  
Yuzhe Dou ◽  
Fanyu Zeng

Most offshore wind turbines are installed in shallow water and exposed to breaking waves. Previous numerical studies focusing on breaking wave forces generally ignored the seabed permeability. In this paper, a numerical model based on Volume-Averaged Reynolds Averaged Navier–Stokes equations (VARANS) is employed to reveal the process of a solitary wave interacting with a rigid pile over a permeable slope. Through applying the Forchheimer saturated drag equation, effects of seabed permeability on fluid motions are simulated. The reliability of the present model is verified by comparisons between experimentally obtained data and the numerical results. Further, 190 cases are simulated and the effects of different parameters on breaking wave forces on the pile are studied systematically. Results indicate that over a permeable seabed, the maximum breaking wave forces can occur not only when waves break just before the pile, but also when a “secondary wave wall” slams against the pile, after wave breaking. With the initial wave height increasing, breaking wave forces will increase, but the growth can decrease as the slope angle and permeability increase. For inclined piles around the wave breaking point, the maximum breaking wave force usually occurs with an inclination angle of α = −22.5° or 0°.


2021 ◽  
Vol 9 (3) ◽  
pp. 264
Author(s):  
Shanti Bhushan ◽  
Oumnia El Fajri ◽  
Graham Hubbard ◽  
Bradley Chambers ◽  
Christopher Kees

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.


2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Jithin Jose ◽  
Olga Podrażka ◽  
Ove Tobias Gudmestad ◽  
Witold Cieślikiewicz

Wave breaking is one of the major concerns for offshore structures installed in shallow waters. Impulsive breaking wave forces sometimes govern the design of such structures, particularly in areas with a sloping sea bottom. Most of the existing offshore wind turbines were installed in shallow water regions. Among fixed-type support structures for offshore wind turbines, jacket structures have become popular in recent times as the water depth for fixed offshore wind structures increases. However, there are many uncertainties in estimating breaking wave forces on a jacket structure, as only a limited number of past studies have estimated these forces. Present study is based on the WaveSlam experiment carried out in 2013, in which a jacket structure of 1:8 scale was tested for several breaking wave conditions. The total and local wave slamming forces are obtained from the experimental measured forces, using two different filtering methods. The total wave slamming forces are filtered from the measured forces using the empirical mode decomposition (EMD) method, and local slamming forces are obtained by the frequency response function (FRF) method. From these results, the peak slamming forces and slamming coefficients on the jacket members are estimated. The breaking wave forces are found to be dependent on various breaking wave parameters such as breaking wave height, wave period, wave front asymmetry, and wave-breaking positions. These wave parameters are estimated from the wave gauge measurements taken during the experiment. The dependency of the wave slamming forces on these estimated wave parameters is also investigated.


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