River Energy

The energy contained in river flows is in essence diffuse, but can be extracted using existing and innovative techniques. Two main energy extraction methods are applicable in rivers: damming of water and extraction of energy from the built up potential energy (head difference), and secondly, direct extraction of kinetic energy from the flowing water.

In the case of a dam the energy yield is higher as a greater water level difference is built up and a higher water flow is led to the turbines. Depending on the water head and flow different types of turbines are applied (Pelton, Francis, Dériaz, propellor, Kaplan, traditional water wheels) in different configurations with vertical or horizontal axis and spiral casing, or designed as bulb turbine. The construction of dams or weirs (in lowland areas) for energy production facilitates also other functions such as the supply of sufficient fresh water for households, agriculture and industry, control of the river discharge and water level (safety against flooding), and improvement of the river navigability. Obviously, however, the construction of a dam in a river has a considerable influence on, in particular, the hydraulic, ecological and morphological properties of the river in a large area upstream and downstream of the dam.  

Turbines that extract directly kinetic energy from the flowing water (rivers, tidal channels) have not widely been applied in the past. New concepts are being developed nowadays based on drag (water wheel like) or lift (wind mill like) principles, having a horizontal or vertical axis, sometimes also in combination with a venturi for a better efficiency. The extraction of energy from a free flow is higher as the flow velocity is higher and the turbine-swept area is larger. 

Deltares can advise on the hydraulic, hydrodynamic and morphological design aspects of both low-head and high-head water power stations, execute numerical flow computations, and undertake scale model studies for gates, spillways, and stilling basins. Also new designs for kinetic-energy extracting turbines can be tested in our laboratory.

In a broader context Deltares can contribute to the set up of operational water management strategies and policies, and the study of environmental and ecological issues.