HYDRAULIC INVESTIGATIONS FOR THE ENVIRONMENTAL IMPACTS DUE TO TIDAL ENERGY DEVELOPMENT

Abstract

New ocean renewable energy has been developing around the world for a goal of reducing greenhouse gas emission. Tidal energy is more powerful and it has potential for future electricity generation among several ocean renewable energies even though not yet widely used. Also tides are more predictable than wind energy and solar energy. SIHWA Lake Tidal Power Plant in South Korea is the largest tidal power installation in the world, with the total power output capacity of 254MW. The project was opened in 2012 and a 12.5km long seawall constructed in 1994 for flood mitigation and agricultural purpose. Power is generated on tidal inflows into the 30km² basin with the help of ten 25.4MW submerged bulb turbines. Eight culvert type sluice gates are used for the water outflow from the barrage. The amount of discharge flow in total ten of turbines is 3,000 m3/sec, and discharge flow in eight of water gate is 8,500 m3/sec. At the time when SIHWA Lake Tidal Power Plant was designed for construction, its flow velocity was predicted as less than 2m/sec in front of water gate. Accordingly, discharge flow should have no significant impact on navigation channels and several berth facilities. It also should not affect on ship navigation. However, within a year after the first run on April 2012, more than 2.5m/sec of flow velocity was generated and it damaged on navigation channels and berth facilities. Increased flow velocity at SIHWA sea area is directly impacting on ship navigation. In severe case, it will cause human and physical damages. In order to prevent these damages, it is necessary to find the causes and countermeasures of increased flow velocity for reduction in flow velocity of discharge.