Production Hydraulique [EN]

Hydropower plants are an important part of the French electricity mix. 

Hydropower plants can be divided into four categories, depending on the size of the reservoir upstream of the plant:

- Pumped-storage hydroelectricity (PSH) plants are hydroelectric units that draw water at off-peak times from a lower basin to fill an upstream reservoir (high altitude lake). The water is then turbined at peak times to produce electricity.

- Lake-type plants associated with a reservoir whose filling time exceeds 400 hours. Lake-type plants are managed on an annual basis, in order to use the available water when it is of maximum value to the power system, while respecting the technical constraints associated with water management in hydraulic valleys.

- Lock-type plants associated with a reservoir whose filling time is between 2 and 400 hours. Lock-type plants are managed on a daily to weekly basis. 

- Run-of-river plants associated with a reservoir whose filling time is less than 2 hours. Run-of-river plants have low modulation capacities and their production is mainly conditioned by hydraulic inflows.  

This graph gives a monthly and annual overview of hydropower production in mainland France (including Corsica), broken down by sub-sector: lake, lock, run-of-river, other.

This graph presents an aggregated view of the producibility contained in water reserves in France.

• The use of water in hydraulic dams is managed in such a way as to optimally distribute the production of the power plants concerned over time, by arbitrating between immediate use, or deferred use in substitution of more costly means of production. This is achieved by estimating the opportunity cost of deferred use of the power plant (or use value). The plant only produces at a given time if the market value of the electricity exceeds the opportunity cost of future use. The value depends on the time in question, the level of consumption, the level of remaining stock, as well as that of other modeled stocks and expected future prices for fuels and electricity. It may therefore happen that the use value of lake hydropower is higher than the cost of thermal power.
• The graph shows, for each year, the evolution of water reserves in aggregated vision and converted into electrical producibility. The evolution of the hydraulic stock depends on the inflows received and the quantity of electricity produced by the hydropower plants.

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Pumped-storage hydroelectricity (PSH): hydroelectric units that draw water at off-peak times from a lower basin to fill an upstream reservoir (high altitude lake). The water is then turbined at peak times to produce electricity.