International Journal of Coastal, Offshore and Environmental Engineering
Volume:6 Issue: 5, Autumn 2021

The use of renewable energy instead of oil and gas reservoirs in the Persian Gulf can be a good platform for renewable energy farms. This study investigates the energy generated by the tidal flow velocity in the Qeshm channel, using a three-dimensional hydrodynamic model, MIKE3, Flow Model FM. By installing a hypothetical tidal turbine from Voith Company, with a diameter of 1 m at seven different stations of the model (respectively from east to west of the channel), the tidal energy from the horizontal flow of the area is calculated. In the mentioned simulation, wind stress and thermohaline flow are ignored so that the dominant current is the current caused by the change of water level due to the tide. The flow velocity pattern in spring and neap tides at Higher High Water (HHW) was then analyzed at the seven stations. The energies of the simulated currents showed that the east side of the channel had more energy potential on the days of spring tides, so that at IP1 station, in the first spring tide, 175 watts of electricity is generated, which in the second spring tides decreases by 28.5%. On the other hand, the west side of the channel had the potential to generate electricity in neap tides. Station IP6 had the potential to generate electricity in both the spring and neap tides, which had more neap tides potential than the spring tides. The difference in power generated in the first and second neap tides at IP6 was only 0.7%, which is less than 30.2 W compared to the first and second spring tides. Therefore, it can be said that according to the shape of the region, the second bend of Qeshm channel was a more suitable place for energy extraction with the assumed tidal turbine in the region.

Biofuels are the up and coming alternative to exhaustible, inenvironmentally and unsafe fossil fuels. Microalgae as a source of biofuels have been widely studied for biodiesel/biogas/biohydrogen/biochar/bioelectricity production and has been gathering much contemplation right away. Increasing in energy demand and in greenhouse gas emission makes it important to develop alternative energy carriers that are renewable, clean and environmentally friendly. The use of arable land for biofuels in some cases has been associated with food insecurities and increased greenhouse gases caused by indirect land use change effects. Microalgae can grow on land not suitable for agriculture and would alleviate these concerns. The high lipid and mineral contents of microalgae render it beneficial for the production of biofuels and value-added products. On the other hand, result in to the reducing pollution and protecting the environment, because as a result of generating electricity in fuel cells or mechanical force in blast engines, the only output is water vapor. This review focuses on the current scenario and future prospects of microalgae aimed at biofuel production and the technologies available for converting the biomass produced into biofuel are analyzed. The goal of this work was to give a comprehensive review on biofuel production from microalgae biomass.

This study is a new design of a vertical axis turbine that generates renewable energy from low-speed currents tidal. Tidal Energy is one of the most important available resources among the renewable and environmentally friendly energy resources in oceans and seas. Tidal turbines are used to produce renewable energy. Some types of tidal turbines widely used and studied are vertical axis tidal turbines (VATT) such as Savonius, Darrieus, Gorlov, Lucid, etc., in which the flow direction is not essential for them. And some types of tidal turbines are Horizontal axis tidal turbines (HATT) which the flow direction is important and often have good performance than vertical axis turbines. These turbines are well suited for absorption of high-speed current, but most ocean areas have tidal flow at low speed. The main purpose of this research is a numerical study of tidal turbines with a horizontal and vertical axis rotor and designing and modeling VATT to increase the power efficiency in low-speed currents. In numerical modeling, the HATT at high speeds has high efficiency, and CP to TSR is more than 0.4, but with the design of the vertical Savonius turbine, with the focus of the flow on the concave blade and the removal of force from the convex blade, almost equality in speed Less than 2m/s. In the modern design of the Savonius turbine, the ratio of CP to TSR has been increased three times and reaches more than 0.3 in compare the simple Savonius classic turbine. Therefore, due to advantages such as easier installation and lower maintenance costs of Savonius turbines, and with the new design, the use of these turbines in renewable energy will be appropriate.

In recent years, scientists have considered the development and utilization of sustainable and environmentally friendly energy resources to replace fossil fuels.  One of the newest topics of new energies is the extraction of energy from salinity gradients in seas and oceans. One of the practical methods of energy extraction from salinity gradient is reverse electrodialysis and delayed osmosis pressure. These methods result from mixing two types of water with different salinity concentrations, which are one of the best places to extract energy in the river estuary, where freshwater is naturally mixed with seawater. In this study, using physical parameters measured in 3 hydrometric stations located in Arvand River, achievable Gibbs energy and electrical energy from reverse electro dialysis method and delayed osmosis pressure as physical model setup were investigated. The amount of Gibbs energy obtained using delayed osmosis pressure method from data from three hydrometric stations in Arvand River shows that Khorramshahr station has the highest amount of extractable energy with 0.75 MJ. By calculating the voltage of two heads of each inverse electrodialysis cell in the three studied stations on the Arvand River, it was found that the highest potential difference with the amount of 80 mV was related to Khorramshahr station. Also, the efficiency of the two devices and the selection of the appropriate geographical location for its location were examined.

Since renewable energy can be a good solution to respond to oil crises, the disadvantages of using them and increasing energy demand in a sustainable way in the future, and because the oceans cover two-thirds of the earth's surface, harnessing the energy of the oceans can be a source of green energy for coastal areas. At present, the generation of electricity from ocean waves by wave energy converters is considered as a potential future energy source in many countries. Currently, the electricity generation from ocean waves by wave energy converters is considered as a potential future energy source in many countries. Therefore this study aims to investigate the potential of wave energy in the Caspian Sea from the Iranian perspective, and in the next step, propose a framework to select an absorber to harvest this energy. Although there are studies to assess the potential of wave energy in this region,but none of them considered more than one type of absorber in the models. To this aim, the wind data samples of the European Center for Medium-Range Weather Forecasts are used to model the Caspian sea by implementing Mike 21 software from which the power and height of waves data are obtained within the years 2001 to 2015. Based on the results of this phase and the geographical conditions, a weighting framework is applied to select an absorber for harvesting wave energy. The results indicate that the best technology to harness energy in the Caspian Sea is the WEPTOS absorber. This technology benefits from low complexity while offering high efficiency.

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.

Development that is not environmentally friendly is not sustainable. One of the methods of sustainable development is the use of renewable energy such as wind. One of the most important sites in Iran with wind energy potential is the Manjil region. Four sites in Manjil region (Manjil, Siahpoosh, Rudbar and Herzeville) were surveyed. In this paper, wind energy potential measurement in onshore and coastal areas evaluates wind energy according to the extensions developed by the authors. The results with scientific achievements and similar software in 4 stages of wind simulation, simulation of conditions the boundary of the range will assess wind power and extractable energy. Summary of spatial fit and arrangement of turbines shows that Manjil power plant in world energy class has sufficient quality of energy production and can be compared with global sites. This site with a nominal capacity of 240 million kilowatt-hours per year is one of the largest sites in the Middle East with a capacity factor of 0.25. Siahpoosh site with a capacity of 410 million kilowatt-hours per year has a limited factor capacity of 8%. This site has a coefficient of variation of 11%, which modeling shows that the choice of 660 MW turbines is not very appropriate and practical. Therefore, it seems that the use of 500 kW turbines has a better capability than 660 turbines on this site. Based on the results, the two sites of Rudbar and Herzeville have a very proportionate factor capacity, so these two sites can be upgraded according to the installation of Class 4 and 3 turbines.