The diagram below shows how electricity is generated in a hydroelectric power station. Summarise the information by selecting and reporting the main features, and make comparisons where relevant.

The given diagram represents the way to generate

electricity

in a hydroelectric

power

station.

Overall

,

electricity

produces during the daytime starting from a river and ending up with a

generator

,

while

the used

water

is re-pumped at night time. In detail, during the day,

firstly

when a dam is opened,

water

in the high-level

reservoir

from a river flows to a

power

station to produce

electricity

. After that, the

water

arrives at reversible turbines which operate a

generator

.

Next,

a

generator

in the

power

station lets the

water

go to a low-level

reservoir

,

also

the generated

electricity

is sent to a national grid by

power

lines connected with the

generator

, at the same time.

By contrast

, at night, the

water

from the low-level

reservoir

is moved reverse to the high-level

reservoir

, by crossing again the reversible turbines. The

water

is pumped to the high-level

reservoir

and after the pumping ends, the dam is closed to keep the

water

stay inside the dam during nighttime.