جستجوی مقالات مرتبط با کلیدواژه « wave energy » در نشریات گروه « مهندسی دریا »

Electric energy consumption is growing almost all over the world. Similarly, using clean resources in coastal such as wave power is also growing. The coasts of Oman Gulf in southeast of Iran is one of the most potential areas for deriving energy from waves. The sea waves are mostly generated by wind and the climate change affect the wind field. Hence evaluating climate change effects on the wave power is essential for energy extraction. In this research, the variation of monthly average in Chabahar bay wave power under the middle scenario of future climate effect has been studied. For this, the CNRM-CM6-SSP2-45 dataset has been downscaled with the Weibull technique, and with a calibrated wave model, wave characteristic has been calculated. Based on the results, the average annual wave power will reach 10.4 kW/m by an increase of 3%. Total wave energy in Chabahar is about 91,000 kWh/m during the year. which will also increase by 3% compared to the same period previous century. In the July and August, the first high energetic months, the wave power increase by 1% on average compared to the previous period. The highest monthly increase occurs in October and with a 277% increase, it reaches 5535 kW/m. The highest monthly decrease of 25% occurs in June and the energy reaches from 13041 to 9513 kW/m.

The use of renewable energies is inevitable due to the limitations of fossil fuels, pollution, and the global increase in energy consumption. Renewable energies are various, so selection and investment in the best option in each region are complicated and depend on multiple parameters. For this reason, this study has used Analytical Hierarchal Process (AHP) to prioritize renewable energy sources in Iran's main ports (located in the Caspian Sea, Oman sea, and the Persian Gulf). The AHP is among the most widely used methods in multi-criteria decision-making in many fields and can include different and contradictory criteria. Renewable energies, including solar, wind, wave, and current, have been analyzed in the main ports' area (5 km radius in sea and port hinterland). The results show solar (photovoltaic) and wave energies are the first and second priorities in all southern ports except Imam Khomeini Port. Imam Khomeini Port is the only port where the current energy is unignorable. In the northern ports, wind energy is the primary option for investment. Wave energy can be exploited only in the Shahid Beheshti Port of Chabahar, located on the Oman Sea shores and directly connected to the open sea. In the ports of Khuzestan province, the photovoltaic power potential is lower than in other southern ports despite the very high solar direct normal irradiation.

Wave energy harvesting, if viable, is a potential energy resource for remote islands like Dumaran Island, Philippines. However, absence of high-resolution wave energy resource information in Dumaran waters hinders the development of Wave Energy Converter (WEC) to overcome current unsustainable means of supplying power, prolonging energy insecurity among its locals.  The focus of this study is to assess wave energy densities for Dumaran Island using high-resolution and validated wave data for the selected sites in Sulu Sea within 100 km radius from the island by using statistical analysis. This was achieved by generating 3-hourly hindcast wave data for 40-year study period (1978 – 2018) in 6 selected sites, using MetOcean Solutions Ltd WW3 Tolman Chalikov (MSLWW3TC) numerical wave model. The wave model was then validated with MIKE 21 Spectral Wave Model FM (MIKE21SW), which generated 3-hourly wave energy data at 14 sites for 5-year study period. Subsequently, wave energy flux time-series was computed and statistically analysed. The validated wave model resulted in low RMSE and high CC results, which indicate good model performance. The study area has low wave energy content, with the average wave energy range less than 4.5 kW/m. High but unstable wave energy was observed during Northeast Monsoon across all sites, and reduction of wave energy near coastal areas due to sheltering effect of Palawan and offshore islands. The hotspot for wave energy is found in the northeast and southeast of Dumaran deep offshore waters, with average annual wave energy of 4.43 kW/m. As mean wave energy at the site is insufficient and grid connection is absent WEC implementation in Dumaran waters is not viable.

In this research, objecting to the use of a lesser-known type of energy source, marine wave potential, the application of Sea-wave Slot-cone Generator (SSG) breakwater was investigated in the Caspian Sea. This study had two main objectives. 1) Investigation of the conditions of each of the selected waves in terms of speed factor in the face of this breakwater 2) Investigation of the scattering of different waves in the Bandar Anzali area on the southern shores of the Caspian Sea. About the first goal, eight waves with different characteristics were selected and applied. According to the simulation results, the wave with a height of 2.825 meters and speed of 6.56 m/s and waves with a height of 0.5 and 2.825 meters and speed of 13.02 m/s, with an efficiency of more than 50%, had the highest efficiency among the simulated waves. Nevertheless, in connection with the second goal, by examining the wave height diagram and the diagram of the specified wave period, most of the waves that occurred in the Bandar Anzali region in 100 days are close to the wave with a height of 0.5 meters and speed of 6.56 m/s with an efficiency of about 7%. It does not have an opinion, and the number of waves that occurred with favorable conditions is less than expected. Therefore, it was found that the use of SSG breakwater in Anzali port located on the southern shores of the Caspian Sea is not economically viable.

In this paper, the effect of the draft depth (as a dimensionless number) and characteristics of the incident wave on free surface oscillation, velocity, and the output power of an OWC has been analytically and experimentally investigated. Therefore, the governing equations of hydrodynamic performance inside the oscillating water column chamber were first presented by assuming a mathematical model based on the potential flow theory. Then, a 1:10 single chamber OWC has been experimentally investigated in a wave tank, by considering the Caspian Sea wave characteristics. Comparing the obtained results showed that there is a good agreement between the theoretical solution and experimental test data. According to the results, increasing the frequency of the incident wave increases the free surface oscillation outside the chamber, while the results inside the OWC are different. In other words, under these conditions, free-surface oscillations inside the OWC and subsequently, the velocity and flow rate of the orifice decrease. So, the power generated will decrease too. Also, the effects of draft depth have been theoretically and experimentally analyzed for three depths and turned out that increasing the depth of drafts from 5 to 25 cm and frequency from 32 to 42 rpm causes a decrease in power generation.

Supplying world future energy is tied with renewable energies and wave energy is one of the biggest resources of renewable energy which is somehow untapped. Oscillating Water Column (OWC), one of the most familiar devices in harnessing wave energy, is still not being properly commercialized due to the complicated hydrodynamic behavior. Offshore OWCs are exposed to higher wave energy; however, the researches on this kind of OWCs is limited. Hence, in this paper, a fully nonlinear two phase flow model of a fixed offshore OWC is developed using Ansys Fluent. Unlike the previous studies, the developed numerical model has the merit of being validated against a relatively large scale physical model (1:15). The results of the model are compared by those obtained in experimental campaign conducted by the authors. Results of both free surface elevation and air pressure in the OWC chamber are compared. Generally, the results showed an admissible accordance between numerical and experimental model. Some discrepancies could be detected in the free surface elevation in the chamber especially for short wave period. This can be attributed to the increase of nonlinear effects in the chamber by increase of wave steepness. The developed model can be applied for further researches on OWCs such as optimization or improving OWC performance.