Hydroelectric power plants produce electricity from water. A dam is built to raise the level of the water in the reservoir. Since the water is falling from a height, it flows with force through the penstock and falls onto a turbine. The blades of the turbine start spinning because of the force of the falling water. The spinning turbine drives the generator to produce electricity. The generator is connected to power lines that carry the electricity to consumers.

Question

How is producing electricity in a hydroelectric power plant different from producing electricity in a natural gas power plant?
A.
Hydroelectric power plants can only be constructed at high altitudes.
B.
Hydroelectric power plants can be constructed far from the source of water.
C.
The water will continuously be replaced as a result of the water cycle.
D.
The water will continuously remove the pollutants produced during energy production.

Answer 1

The best choice that highlights a difference between producing electricity in a hydroelectric power plant and a natural gas power plant is:

C. The water will continuously be replaced as a result of the water cycle.

In hydroelectric power plants, the water utilized is part of the natural water cycle, which means it can be replenished through precipitation and other natural processes. In contrast, natural gas power plants rely on fossil fuels, which do not get replenished in the same way and generate emissions that contribute to pollution.

Other options do not correctly differentiate the two types of power generation:

• A is incorrect because hydroelectric plants can be built at various altitudes, not just high altitudes.
• B is also incorrect; hydroelectric plants need to be constructed near a water source.
• D is misleading since while water may help dilute pollutants, it does not actively "remove" them in the same way as filtering or treatment processes would.