Research on energy storage technologies for marine current energy systems

Ocean is a huge renewable energy source, a tremendous amount of electric energy can be extracted from marine currents. However, the electric energy extracted from the marine currents is very volatile due to the swell effect and the periodicity of the tidal phenomenon. Energy storage system can play a crucial role in the marine energy system to improve the power quality and make the marine generation system more reliable. In this paper, different energy storage technologies are introduced and discussed. It is shown that super-capacitor and flywheel are more suitable for compensating short-period power fluctuation due to swell effect while sodium-sulfur batteries and flow batteries are favorable for smoothing the long-period power fluctuation due to the tidal phenomenon. Finally, it is concluded that the hybrid energy storage technology has a great application prospect in the marine current energy system.