Located 400 meters underground, the Montézic hydroelectric plant is the second most powerful in France, with its 920 Megawatts. It has the specificity of being a station of transfer of energy by pumping, at the cutting edge of technology, which produces in less than 2 minutes, the first of renewable energies, thehydropower. Commissioned in 1982, the Montézic site is the latest in the Lot-Truyère hydroelectric chain.
Montézic hydroelectric plant
The construction of the hydroelectric complex
The construction site for the Montézic hydroelectric facility began in 1976, after four years of studies and prospecting. The piercing of the access gallery to the power plant, with a length of 850 meters was the first construction site. Then there was the construction of three dikes (Monnès, l'Étang and Liaussac) to form the upper basin (Lac de Montézic), the fixed body of water at Saint-Gervais, the spillway, the two intakes of water, the two high pressure galleries, a low pressure gallery, a water intake in the lower basin (Couesques lake) and the construction of the plant itself. This one was dug in the granite, it is 142 meters long, 35 meters high and 25 meters wide. The work was completed in December 1982 with the commissioning of unit 4. A gigantic construction site, in which 750 people took part, including many locals.
The latest of the 15 power stations built on the Lot-Truyère hydroelectric chain, Montézic is the strongest link with its 920 MW. This plant, completely integrated into the landscape, since it is located directly in the granite, 400 meters underground, is the largest plant in Aveyron, first department of France producer of renewable energies.
The technical characteristics of the Montézic dam
Upper reservoir of Montézic :
- Surface: 245 ha
- Capacity: 30 million m3
- River: the Plane
Couesque Lower Reservoir :
- Capacity: 56 million m3
- River: the Truyere
Monnes dyke :
- Height: 57 meters
- Length: 820 meters
Pond Dyke :
- Height: 30 meters
- Length: 680 meters
Dyke of Liaussac :
- Height: 20 meters
- Length: 600 meters
Montezic power plant :
- Date of commissioning: 1982
- Remote control from Toulouse
- Drop height: 420 meters
- Production groups: 4
- Total power: 950MW
- Production: it corresponds to the annual residential consumption of more than twice the department of Aveyron (620 inhabitants)
Production
The Montézic hydroelectric plant is a very special production unit. It's about a Pumping Energy Transfer Station (STEP) whose main asset is toadapt in real time production to consumption, by allowing the storage of electricity in the form of water. Indeed, by definition, electricity cannot be stored, it must be produced according to needs.
The principle of the WWTP is as follows: when the network needs electricity, the WWTP uses the water in the upper basin to produce electricity (turbine mode). It is the force of the water that turns the turbine.
At times of low consumption, when electricity is available on the network, the water is pumped (pump mode) from the lower reservoir (Lac de Couesque) to the upper reservoir (Lac de Montézic). It is then the network that supplies the alternator, like an electric motor. It rotates the turbine in the opposite direction to raise the water to the upper reservoir. The stock of potential energy is thus reconstituted for a new production cycle, independently of water coming from the sky and/or other natural waterways.
Tourism
During the construction of the Montézic hydroelectric development, EDF was a pioneer by creating a 16-hectare lake in the municipality of Saint-Symphorien-de-Thénières: Saint-Gervais lake, with a constant water level in order to to accompany the local tourism development. The lakes of Montézic and Saint-Gervais are important assets of the tourist offer of the Truyère valley and allow you to practice numerous outdoor activities.
Nautical activities
Lake Saint-Gervais, allows you to indulge in the joys of water. The bathing is supervised in July and August. A water sports, allows you to go pedalo, paddle, canoe or windsurf. A playground for children is also present.
Fishing
La fishing can be practiced on Lake Saint-Gervais (16 ha) and on Lake Montézic (250 ha) all year round (2nd fish category), with a fishing license (on sale at Saint-Amans-des-Côts Information Office).
Le Saint-Gervais lake has a maximum depth of 10 meters. Navigation is authorized by rowing only. The main fish are: zander, perch, pike, carp, tench, chub, roach, rudd, bleak. Several trout releases are carried out by the AAPPMA de la Viadène.
The lake is very easily accessible over its entire area, a footpath goes around the lake and there are several car access points.
Le lake of Montezic has meanwhile has a maximum depth of 50 meters. Only shore fishing is allowed for safety reasons. Its operation is based on the transfer of water between the Couesque and Montézic reservoirs (high daily tidal ranges +/- 8 m)
The main fish are: zander, pike, perch, zander, catfish, roach, rudd, bream, carp. About 11 kilometers of shoreline provide access to the lake.
Walk
All year round, you can walk all around the lake of Saint-Gervais : the trail is 2,5 kilometers long, it is laid out so that for all can go around it, including people with reduced mobility. All along the route, benches are arranged to allow you to rest, or simply admire the landscape; as well as two information tables concerning the habitat of the body of water (fish and birds) and panels on the flora. Three spaces with picnic tables and an area with barbecues are present.
