Performance analysis of dual sphere wave energy converter integrated with a chambered breakwater system
Introduction
In a recent report by Renewables global status report (2019), the estimated global electricity production from renewable sources is found to be 26.2% with a major contribution of 15.8% from hydropower [1]. Ocean energy, on the other hand, has contributed to 0.4% towards electricity production. Amongst various renewable energy resources, ocean wave energy has a huge potential due to its abundance covering over 71% of the earth. Falcão reviewed the development of wave energy converters, their hydrodynamics, and how the control system for wave energy absorption has evolved since the 1970s [2]. Among the WECs classified based on their operating principle, location, and size of the converter [3], a point absorber was found to be the cost-efficient technology [4]. Though there have been advancements in the area of development of different wave energy converter (WEC) designs the high cost of construction limits its commercialization. Integrating the WEC with other marine facilities is found to improve the power generation performance of the WECs and thereby promote cost-sharing [5, 6]. Oscillating water column [[7], [8], [9]] and overtopping breakwater [[10], [11], [12], [13]] are the two types of WEC successfully integrated with existing coastal defense structures. Introducing a WEC in front of the seawalls is found to improve the efficiency of WEC [14, 15]. The performance of a single WEC in front of an infinite vertical wall has been investigated through the analytical method [[16], [17], [18]]. A numerical study also analyzed the performance of a heaving point absorber near a vertical wall and found that the performance of the device was significantly improved [19]. The integration of WEC with other marine facilities for the medium wave energy potential regions was reported to be beneficial [20]. In India, the approximated wave power potential across the coastline of 7500 km is estimated to be about 41 GW [21]. Also, 23% of the Indian coastline is reported to be affected by erosion [22]. Integrating a WEC with the chambered breakwater (CBW), a concept presented by Jarlan [23] is found to improve the performance of the WEC and CBW [24]. The wave attenuation characteristics of single and multiple CBW were investigated in past studies [[25], [26], [27], [28], [29]]. The reflection and wave attenuation characteristics of the CBW are found to depend primarily on the porosity of the front wall and relative chamber width. The wave absorbing ability of the Jarlan type perforated breakwater was improved after installing a horizontal porous plate inside the chamber [30]. Various configurations of Jarlan-type perforated wall caissons considering the wave reflection, transmission, and wave forces from different cases of perforated/slotted coastal structures were classified [31]. The past studies revealed that the studies attempting to investigate the utilization of the wave energy inside the chambered breakwater using a WEC are scarce. Krishnendu and Balaji [24] investigated an idea of integrating the CBW with the single heaving type WEC system; this offered a dual functioning performance in which, one can absorb the wave energy and another can partially convert the trapped wave energy to usable power. In the integrated system, the incident waves are allowed to pass through the seaside porous wall of the CBW, and by varying the chamber width to wavelength (B/L) ratio, these waves are trapped inside the chamber. The trapped oscillating wave energy can then be extracted using a suitable WEC without compromising the primary purpose of the CBW to absorb the energy. The performance of single S-WEC integrated with the CBW was studied by varying the distance of its installation and examined for its adopted range of wave conditions in the previous study. In one case the S-WEC was installed at a position 0.50 m away from the center of the chamber towards the porous wall and in the other case, the S-WEC was installed at the same distance from the center towards the impermeable wall [24].
The present study investigates the performance of dual S-WEC, installed at two different positions working concurrently inside the chamber. In this system, the first S-WEC is installed near to the porous wall and the second S-WEC is installed near to the impermeable wall, at a distance of 0.20 m from the respective walls. The performance of the single and dual S-WEC integrated with the CBW is compared and the significance of the position of the S-WEC inside the chamber in improving its performance is highlighted. The paper is structured as follows. Section 2 describes the experimental and numerical details. The validation of the numerical model is presented under Section 3 (Results and Discussion) followed by the outcomes from this study described in Section 4 (Conclusions).
Section snippets
Materials and methods
The performance of the CBW integrated with dual S-WEC (I and II) is investigated through experiments and the power generation capability of the dual S-WEC is investigated through the numerical method. The different cases investigated are as follows;
Case i – S-WEC alone (Reference Model, RM)
Case ii – Single S-WEC integrated with the CBW
Case iii – Dual S-WEC (I and II) integrated with the CBW
Validation of the numerical model
The response of the dual S-WEC I and II (Case iii) integrated with the CBW are investigated through experimental and numerical investigation. The wave elevations measured by the wave probes installed at the position near to dual S-WEC in the experimental set-up are given as input for the numerical simulation. The performance of the S-WEC I and II integrated with the CBW installed at positions near to the porous and impermeable wall (0.20 m from the walls) are examined. Fig. 5 shows a typical
Conclusions
The performance of dual S-WEC integrated with the CBW is examined through experimental and numerical investigations in this study. The reflection characteristics from the integrated system, the heave response of the dual S-WEC, power generation capability of the dual S-WEC, and the influence of the position of installation of the S-WEC inside the chamber are the key parameters studied. The following conclusions can be drawn from this investigation:
- 1
The average reflection from the CBW integrated
Authors statement – individual contributions
P Krishnendu: Execution of experiments, analysis of experimental data, numerical model simulation and investigation, writing-original draft preparation.
Balaji Ramakrishnan: Technical supervision, planning of experiments, writing-reviewing & editing.
Declaration of Competing Interest
None
References (37)
- H.E. Murdock, D. Gibb, T. André, F. Appavou, A. Brown, B. Epp, J.L. Sawin, Renewables 2019 Global Status Report,...
Wave energy utilization: a review of the technologies
Renew. Sustain. Energy Rev
(2010)- et al.
Various technologies for producing energy from wave: a Review
Int. J. Smart Grid Clean Energy
(2013) - et al.
Performance comparison of the floating and fully submerged quasi-point absorber wave energy converters
Renew. Energy
(2017) - et al.
Experimental investigation on hydrodynamic performance of a breakwater-integrated WEC system
Ocean Eng
(2019) - et al.
Hydrodynamic performance of an array of wave energy converters integrated with a pontoon-type breakwater
Energies
(2018) Caisson breakwaters embodying an OWC with a small opening – Part I: theory
Ocean Eng
(2007)- et al.
Mutriku wave power plant: from the thinking out to the reality
- et al.
On design and building of a U-OWC wave energy converter in the Mediterranean Sea: a case study
- et al.
Wave loadings acting on overtopping breakwater for energy conversion
J. Coast. Res.
(2013)
Innovative rubble mound breakwaters for overtopping wave energy conversion
Coast. Eng.
Prototype overtopping breakwater for wave energy conversion at port of Naples
Wave loadings acting on innovative rubble mound breakwater for overtopping wave energy conversion
Coast. Eng.
An approximate theory for the performance of a number of wave-energy devices set into a reflecting wall
Appl. Ocean Res.
Numerical performance investigation of an array of heaving wave power converters in front of a vertical breakwater
Wave diffraction from a uniform cylinder in front of a vertical wall
Ocean Eng.
Wave radiation by a uniform cylinder in front of a vertical wall
Ocean Eng.
Wave diffraction from a truncated cylinder in front of a vertical wall
Ocean Eng.
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