Abstract
Increasing concerns about the depletion of fossil resources and the issue of environment lead to a global need for producing more clean energy from renewable sources. Ocean is appreciated as a vast source of renewable energies. Considering marine renewable energies, it can be noticed that significant electrical power can be extracted from marine tidal currents. However, the power harnessed from marine tidal currents is highly fluctuant due to the swell effect and the periodicity of the tidal phenomenon. To improve the power quality and make the marine generation system more reliable, energy storage systems can play a crucial role. In this paper, an overview and the state of art of energy storage technologies are presented. Characteristics of various energy storage technologies are analyzed and compared for this particular application. The comparison shows that high-energy batteries like sodium–sulphur battery and flow battery are favorable for smoothing the long-period power fluctuation due to the tide phenomenon while supercapacitor and flywheel are more suitable for eliminating short-period power disturbances due to swell or turbulence phenomena. This means that hybrid storage technologies are needed for achieving optimal results in tidal marine current energy applications.