Producing hydroelectricity consists in using the driving force of a river to produce electricity by passing through turbines. This type of production does not generate any atmospheric emission or waste and it is by far the leading source of renewable energy.
The hydraulic turbine was invented at the end of the 19th century to drive electric generators, thus it gave rise to the first hydropower plants. This was followed by the construction of dams of all sizes designed to channel the driving force of water to produce electricity in France and elsewhere in the world.
Advantage: hydroelectricity does not emit atmospheric pollution or waste. Readily useable, hydroelectricity is a key resource of a mix of renewable energies that guarantees the security of the electricity grid. Hydroelectricity production now represents 75% of French renewable production and 13% of its total electricity production. Therefore water is by far the leading source of renewable energy for electricity production in France. On the global scale hydraulic energy makes up 16% of the world’s total electricity production.
A dam diverts part of the flow of a river to a headrace canal on which a hydropower plant and lock are built. The water passes through turbines as it arrives at the plant and is then discharged back into the river downstream. This method, called “run-of-the-river” operation, is used by CNR. The hydroelectric turbines capture the energy supplied by the head of water and the flow and transfer it to an alternator that converts it into electricity. This electricity is distributed to consumers via a high voltage grid.
The dam allows a constant minimum flow, called compensation water, to pass through to the old, bypassed section of the Rhone to preserve the aquatic habitat. The compensation water, whose flowrate is determined by the public authorities, is partially harnessed by small hydropower plants (SHPP).
Compensation water – expressed in m3/s – is the minimum flow maintained at a lower level of any structure built in the bed of a river to ensure on a permanent basis the life, passage and reproduction of species living in it. It is determined by the public authorities. The compensation water of CNR’s development schemes is returned to the bypassed sections of the Rhone to preserve the aquatic habitat.