Feasibility of a self-powered movable seawall using microtidal energy in Japan

The technology for closing port entrances using movable gates as a tsunami countermeasure has recently garnered increasing attention in Japan. However, it is not possible to mechanically operate the gates if power is lost because of a disaster. Accordingly, this study proposes a self-powered movable seawall system that utilizes microtidal energy generated by port closure for operating the gates. As tidal ranges in Japan are not favorable for power generation, the feasibility of the proposed system was assessed at 56 ports throughout Japan. The self-powered system was found feasible at nine ports during both spring and neap tide and at 14 ports during spring tide, whereas the tidal range was too small to operate the system at the other 33 ports. Moreover, 20 feasible ports were located such that tsunamis are predicted to occur in the scenario of a megathrust earthquake, which has a 90 % occurrence probability in the next 40 years. Surplus electricity is expected to be generated on-site with the proposed system, even if a power outage occurs, which is especially valuable for urgent disaster response and business continuity in industrial areas. Our findings outline a synergistic system between disaster prevention and the use of renewable energy.