There are several kinds of energy resources in the ocean but the utilization of the ocean energy is far behind the other natural energies such as solar and wind. A feasibility study on the tidal current power generation by making use of a bridge pier in the narrow strait is introduced in this paper. There are several advantages in making use of a bridge pier for the tidal power generation. Current velocity increases near the pier, therefore the tidal power generation becomes more efficient because the power is proportional to the cubic of the current velocity. Furthermore, the pier is convenient for the maintenance of the hydraulic turbine and the power unit. The project is now underway at the Ikitsuki Bridge in Tatsuno-Seto Strait of Nagasaki Prefecture, where the tidal current is continuously measured by the bottom mount ADCP. The numerical simulations for the tidal current were conducted by the MEC Ocean Model, and the results were compared with the measurements. A long term estimation of the tidal current power is presented and the variation of the power by the lunar period is discussed.
Promotion of the utilization of natural energy is urgent as a countermeasure against global warming. There are several kinds of energy resources in the ocean but the utilization of the ocean energy is far behind the other natural energies such as wind, solar, ground thermal, small and medium hydraulic plants and biomass. In Japan, total output of wind power was 463MW in 2002 and the target of the government is 3000MW in 2010. Since the density of water is 800 times greater than air density and the power of the flow is proportional to cubic of the fluid, the power of ocean current of 2 knots is equal to the wind flow of 9m/s.