This paper focuses on the applicability of a Darrieus-type cross-flow turbine for tidal power generation at sites with high tides less than 5 m. The features of the Darrieus turbine are to have a simple structure and to enable the operation with flow reversals in comparison with the conventional type turbines. A model of a Darrieus runner with the radius of runner pitch circle R = 0.185 m installed in two different flow passages, one of which has a simple structure with parallel walls and the other has a symmetrical convergent inflow passage to hold the efficiency high, was tested for low head hydro-power generation. A numerical simulation of tidal power has been carried out in two stages. First the experimental data was given to the numerical model to provide a relation between the sizes of the turbine and the pond area for the optimum extraction of tidal energy. Then, real data for a potential site in Japan was used to predict the electricity energy generation for the optimum pond size.
Tidal energy is one of the most abundant clean form of renewable energy in the world, which is continuously exploitable in contrast to solar energy where the availability is confined only for day time. Besides, tidal currents have comparatively higher energy density than other common renewable energy resources such as wind, solar etc. Extracting energy from the ocean has intrigued researchers over centuries and at present, there are few tidal power stations throughout the world equipped with conventional type turbines operating at the total head of over 5 m beneath which they become uneconomical (I). Hence, the vast energy potential is still remaining untouched. Therefore, a new kind of turbine system equipped with the Darrieus- type cross-flow runner, having economically attractive features of simple construction, cost effective structure, easy installation with little siteworks and maintenance free operation, is proposed.