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 day-to-night steps of the generation of

electricity

Use synonyms

from a hydroelectric power station.

Firstly

Linking Words

, the river flows into the high-level

reservoir

Use synonyms

which is blocked by a dam to preserve

water

Use synonyms

. During the daytime, when the intake below the dam is open, the

water

Use synonyms

flows from the high-level

reservoir

Use synonyms

through reversible turbines in the power station which operate as generators to the low-level

reservoir

Use synonyms

. As turbines spin

while

Linking Words

water

Use synonyms

runs through, they will generate

electricity

Use synonyms

which will later be transmitted to the national grid through power lines and

then

Linking Words

be distributed for use.

In contrast

Linking Words

, during the nighttime, reversible turbines work in a reserve way, which means they will pump

water

Use synonyms

back into the high-level

reservoir

Use synonyms

from the lower one as the intake of the dam is closed. As the diagram displays, the generation of

electricity

Use synonyms

from hydroelectric stations does not involve any procedure

that is

Linking Words

harmful to nature. In conclusion, it is an environmentally friendly way to produce

electricity

Use synonyms

.