Methods for Rendering Biosafety of Elements in Flow Paths of Hydraulic Turbines

Hydroelectric power belongs to renewable energy sources and contributes a considerable percentage of the electrical energy generated in the world. Its advantages include no carbon dioxide emission, excellent maneuverability, and high energy effectiveness. However, disadvantages do also exist caused by the influence of hydropower facilities on the bioenvironment. This paper presents a review of the most characteristic effects of elements of the flow path of hydroturbines during their operation on biofauna (fish and plankton). The most popular design solutions are examined, which are aimed at reducing the risk of negative impact of the elements of the flow path of hydraulic turbines on the bioenvironment. Obviously, the implementation of these solutions will deteriorate the performance of hydraulic turbines. However, we should bear in mind that the main purpose of these solutions is to ensure the biological safety of facilities, while their energy characteristics do not receive proper attention. The paper presents in some detail an option for rendering environmental safety, which is the modernization of the runner hub by eliminating the gaps between the blades and the hub. Numerical simulation has revealed that the application of a runner with the modified hub increases the hydraulic resistance, decreases the flowrate, and, as a result, reduces the generated power. An analysis of the simulation results has suggested that, despite some decrease in the energy characteristics, it seems worthwhile to develop biologically safer flow path design versions. In addition, a conclusion has been made that the flow path can be further modified to compensate for power losses.