Production – Hydraulique : RTE Bilan électrique 2020

Sharp increase in hydropower generation

Hydropower generation increased between 2019 and 2020, on the back of strong water reserves starting early in the year. Output rose by 8.4% year-on-year.

Hydropower generation by type of plant

The reservoirs of plants with poundage, usually located in lakes below midsized mountains, can be filled in two to 400 hours. They are used for daily, and even weekly modulation (daily peaks in demand, between business and nonworking days, etc.).
Run-of-river plants are primarily located on plains and have low reservoirs that can be filled in less than two hours. They thus have little capacity for modulation through storage, and their production depends on water flows.
Reservoir plants are built at the foot of midsized and tall mountains and have a filling period of more than 400 hours. They are used for seasonal storage.
“Other” hydropower plants are tidal and pumped storage plants (Station de Transfert d’Energie par Pompage – STEP). Tidal power plants harness energy from tides in coastal areas with strong currents (difference in water levels between successive high and low tides). These plants harness tidal ranges to produce electricity, making use of the difference in heights between two basins separated by a dam.

STEP plants operate in pumping-turbining cycles between a lower and an upper reservoir, using reversible pump-turbines. They are an efficient storage tool and help ensure the balance of the power system. If the reservoirs have natural inflows, the turbines fall into the “mixed pumped storage” category. Otherwise they are considered “pure pumped storage”.

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Record water reserves contributed to security of supply in the winter of 2020

Water reserves (hydraulic stock) are associated with reservoir-type hydropower plants that take a long time to fill and are managed seasonally. Reserves decline in winter, when these plants run often, and are then replenished in spring, when the snow melts. They currently remain at the highest level observed in the past ten years.

Hydrological conditions were good in 2019, so water reserves were very high in January 2020 and remained above the 2019 level since reservoir plants were used less often through the spring. Between week 6 (from Monday, 8 February to Sunday, 14 February) and week 23 (from Monday, 7 June to Sunday, 13 June), water reserves remained more than 50% above the 2019 level, thanks to significant precipitation. Starting in week 33 (from Monday, 16 August to Sunday, 22 August), 2020 reserves fell back toward the previous year level. In Week 31 (from Monday, 27 July to Sunday, 2 August), generation rose to the highest level on record for the past five years (3,100.55 GWh).

Moreover, careful management by hydropower operators allowed them to head into the winter with high reserves, which in turn made the operation of the power system more secure.

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Pumped storage stations (STEP)

Pumped storage stations, or STEP in French, are part of EDF’s electricity generation fleet, and their primary function is to “store” energy. These plants comprise two reservoirs (upper and lower) and a power plant located near the lower reservoir. The idea is simple: water is pumped from the lower reservoir to the upper reservoir during off-peak periods, to constitute a reserve. This stored water is then directed to the turbines (i.e. from the upper to the lower reservoir) to generate electricity when demand is high.

Source: EDF

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Sharp increase in hydropower generation

Record water reserves contributed to security of supply in the winter of 2020

Pumped storage stations (STEP)

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