History of hydropower

The origin was the mechanical power of water which was used via paddle wheels. The first hydroelectric plants emerged in the late 19th century thanks to the invention of the dynamo. They were often the result of converting former mills previously used in industry, in particular the paper industry.

Hydropower is the oldest source of electricity generation in France.

Schéma production hydroélectrique

The principle:

To generate electricity, the power plants comprise four main elements:

  • A water supply
  • A turbine
  • An alternator
  • A transformer

The various power plant types:

Today, electricity is produced by power plants which can be grouped into two categories:

  • Run-of-river power plants which can be high or low head.
  • Impoundment power plants which can produce electricity on demand

Run-of-river power plants

These are located on the banks of rivers and use the water’s energy to produce electricity. The water returns to the river downstream of the plant.

The power plant is referred to as High Head when the water is delivered from a high level to a power plant located several dozens of metres lower down via a penstock.

These power plants are present where the flow of water is slow and there is a significant difference in height.

Conversely, low head power plants are characterised by a strong water flow and a relatively small height difference.

Schéma centrale de haute chute
High head power plant
Schéma centrale de basse chute
Low head power plant

Impoundment power plants

Impoundment power plants, commonly known as dam or lock power plants, allow water to be stored to enable several hours, or even several days, of continuous operation of the power plant, and are mainly used for grid balancing. In fact, they can be adjusted in real time to suit demand.

Some of these power plants can “pump” the water into the upper lake. This is known as PETS: Pumped Energy Transfer Station.

In figures

In France, hydropower is the second largest source of electricity generation and the first renewable source. In 2019, the total production was 62.1 TWh, or 11.2% of the total electricity production in France.

The total available output from the French hydraulic park is 26 GW.