WELCOME TO
THE WATER INTAKE SUPPLYING
W
?
is the first source of
renewable energy in France.
Since electricity cannot be
stored, the reservoirs formed
by dams represent an
economic and ecological
solution.
gence.net | 07/11
THE EDF HYDROELECTRIC PEYRAT-LE-CHÂTEAU POWER STATION
HYDROELECTRIC POWER, HOW DOES IT WORK?
A hydroelectric dam works like a water mill: the water behind the dam is directed into a turbine which rotates and it is the combination of
Water intake
the head and the flow rate of water which produces the force of the water and rotates the turbine. The turbine drives an alternator which
generates electrical current. The transformer then steps up the voltage to facilitate the transport of electricity over long distances.
VASSIVIERE’S DAM
WATER INTAKE SUPPLYING
Headrace tunnel
Surge tank
Head gate chamber
THERE ARE 3 TYPES OF HYDROELECTRIC POWER STATIONS:
POWER STATIONS WITH A HIGH HEAD
In mountainous regions, water is held back by building a dam, behind which the water is stored in a reservoir. Such reservoirs provide reserves of water forming true
stores of potential energy which is available at all times, to satisfy temporary demand for electricity (peak periods, severe cold, unscheduled shutdown of another
power station…) In order to create enough difference in level between the water intake and the power station (head of more than 300 m), water flows through
tunnels, penstocks or headrace channels. The power station is not in the toe of the dam to enable the water to gather enough speed to drive the turbine. Such power
stations are known as high head power stations.
Penstock
POWER STATIONS WITH A MEDIUM HEAD
In medium-height mountainous and hilly regions such as the Limousin, slopes of rivers are steep enough and flow rates high. We therefore create a reservoir of water
Turbine
In this case, the term “schemes with a medium head” is used.
Alternator
Transformer
with a head of between 30 and 300 m and the power station can be installed in the toe of the dam or, as is the case at Vassivière, 3 km below, at Peyrat-le-Château.
UNDERGROUND POWER STATION OF PEYRAT
Control building
“RUN OF THE RIVER” POWER STATIONS WITH A LOW HEAD
Large rivers, like some in the Limousin, have a slight gradient but a high flow rate and the resulting head is in tens of metres; water cannot be stored and that is why
such power stations generate electricity continuously and help cover everyday demand.
Tailrace (underground)
High tension line
GLOSSARY : PENSTOCK
A pipe carrying water from the lake to the hydroelectric power station.
WHAT IS A WATER INTAKE USED FOR?
When there is a demand for electricity, an automatic system of gates opens and water from the lac de Vassivière is sent down a tunnel and a penstock of more than 3 km to the
turbines of the Peyrat-le-Château power station, which start to rotate. The water is then returned, in its natural state, to the river Maulde downstream of the dam and the power
station thanks to an underground tunnel 3,800 m long.
N° 3
vous
êtes ici
If you wander along the lakeside paths and in certain locations (pontoon, river taxi, beaches, etc.)
of the lac de Vassivière, you will discover technical or historical information concerning the dam.
hydro-centre.edf.com
www.lelacdevassiviere.com
Conception : L-
O
DID Y U KN
O
Hydroelectricity