Tidal power plant in Saemangeum

Abstract

This study investigates the possibility to build and operate a Tidal Power Plant (TPP) in Saemangeum in South Korea. The objective of the study is to investigate if a TPP would be technically possible and economically feasible for Saemangeum. This has resulted in a design for a Tidal Power Plant. All decisions were made taking into account possible future shifts in facts in economy, energy prices and spatial planning ideas. The most important future functions will be polders for agricultural, industrial or residential purposes and a fresh water basin. A design without one of these functions is most likely to be rejected during the decision process. Existing plants and their performances have been studied as well as several feasibility studies made throughout the years, including the Sihwa project, a single, low basin plant which is at present under construction in South-Korea. A single, high basin and a single, low basin scheme are the most interesting schemes for the Saemangeum case. A bulb turbine is the most suitable type of turbine for tidal power. A Storage Area Approach Model was made to predict the energy output. The possibility to vary the basin area (including the depth-storage relationship) is built in, as well as the possibility to vary the number, efficiency and rated head of turbines (related to the head and flow velocities) and additional sluicing capacity. Also the construction costs, a Net Present Value calculation and the annual energy output are some of the output parameters of the model (with varying discount rate, future energy price). For various reasons it was decided that a layout with the basin area of 114 km2 at MSL must be selected and equipped with a low basin plant: This layout contains a large inter tidal zone, both a fresh water basin and polders, and it turns out to be the economically most feasible option. The selected layout contains a fresh water basin of 90 km2. Generation will only take place in one direction, from sea to basin (flood generation). No extra sluicing capacity is needed, as the 300 meters of present sluice length are sufficient. The powerhouse will be equipped with 18 bulb turbines (runner diameter 7.5 m) and generators, having a total installed capacity of 142 MW. The plant will generate approximately 454 GWh per year and the construction costs will amount to 286 Million US$. For the construction process a cofferdam consisting of circular cells and connecting cells is built around the future TPP power house location. At the barrage side the circular cells have a diameter of 31.8 m and at the basin side the circular cells have a diameter of 25.2 m. The given parameters have been determined by an economic optimisation. The numbers given above are based on assumptions: the plants design has a maximal Net Present Value after 40 years, with a discount rate of 4 %, an annual rise of energy price of 4 % and an actual energy price of US$ 0,03 per kWh. This production price has been set at US$ 0,03 per kWh, because the plant is expected to be able to compete with other energy sources. Under these assumptions tidal power in Saemangeum turns out to be attractive and feasible. The Net Present Value after 40 years of operation is US$ 187.6 Million for a discount rate of 4 % and an expected annual rise of energy price of 4 %. The break even point will be reached after 25 years of operation and the Internal Rate of Return is 6.5 %.