Abstract
A three dimensional Marine Environmental Committee (MEC) model was run to predict the environmental impacts of marine current turbines (MCTs). The removal of momentum due to the rotation of turbine blades should be taken into account in addition to the drag of the blades and their supporting structures. Numerical simulation was carried out assuming that several MCTs are installed in the simple strait. As a result, the range of the reduction in current velocity is depending on the number of installation of MCTs.