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 diagram illustrates the

process

of a hydroelectric power station producing and storing

electricity

during the day and night.

Overall

, during the day, the power produced in

this

process

mainly comes from the flow of

water

from a high-level

reservoir

to a low-level one

while

at night, the

water

is pumped back into the high-level

reservoir

to regenerate

electricity

the next day. In the daytime, the

water

from the river accumulates in the high-level

reservoir

which holds large amounts of

water

before approaching the opening dam. In the meantime, some of the

water

flows down before reaching reversible turbines connected to an operating generator which produces

electricity

and

then

delivers

electricity

produced in

this

process

to the national grid via power lines. Afterwards, the

water

is delivered into the low-level

reservoir

. At night, the reversible turbines driven by the generator will pump

water

from the low-level

reservoir

back to the high-level one, which is the opposite

process

from the daytime. The

water

pumped up will be stored in the upper

reservoir

and can be utilized to generate

electricity

again the next morning.