Dams: The Impact and Function

What percentage of renewable electricity production is accounted for by hydroelectric power?

• 10%

• 15%

• 30%

• more than 50%

Answer explanation

Hydropower accounts for more than 50% of renewable electricity production globally. In 2022, the sector produced about 15% of total electricity generation from all sources.

What is the primary principle behind the operation of hydroelectric power plants?

• Conversion of kinetic energy into potential energy

• Conversion of potential energy into electrical energy

• Conversion of thermal energy into electrical energy

• Conversion of chemical energy into mechanical energy

Answer explanation

Hydroelectric power plants primarily operate by converting the potential energy of stored water in a reservoir into electrical energy as the water flows down through turbines, generating electricity.

What is the highest efficiency rate of modern hydroelectric plants in energy conversion?

• 50%

• 75%

• 85%

• up to 95%

Answer explanation

Modern hydroelectric plants can achieve energy conversion efficiencies of up to 95%. This high efficiency is due to advanced turbine designs and optimal water flow management, making 95% the correct answer.

What is one of the ecological impacts of dam construction and operation?

• Increased biodiversity

• Enhanced natural water flow

• Alteration of natural water flow

• Decreased energy production

Answer explanation

Dam construction alters natural water flow, impacting ecosystems, sediment transport, and aquatic habitats. This disruption can lead to decreased biodiversity and changes in species composition, making it a significant ecological impact.

Explain how dams reshape landscapes.

• Dams create small ponds that have minimal impact on landscapes.

• Dams significantly alter landscapes by creating large reservoirs that store water, effectively changing the natural flow of rivers.

• Dams have no effect on landscapes.

• Dams only affect landscapes during construction.

Answer explanation

Dams reshape landscapes by creating large reservoirs that store water, which alters the natural flow of rivers. This significant change impacts ecosystems, sediment transport, and local geography, unlike minimal or no effects suggested by other options.

Describe the role of gravity in hydroelectric power generation.

• Gravity has no role in hydroelectric power generation.

• Gravity is used to lift water to higher elevations in hydroelectric power plants.

• Gravity causes water to fall, converting potential energy into kinetic energy, which is then used to generate electricity.

• Gravity is only important for maintaining the structure of the dam.

Answer explanation

Gravity plays a crucial role in hydroelectric power generation by causing water to fall from a height. This fall converts potential energy into kinetic energy, which is harnessed to generate electricity.

Explain how turbines function in hydroelectric power plants.

• Turbines store energy for later use.

• Turbines convert the kinetic energy of flowing water into mechanical energy, which is then converted into electrical energy.

• Turbines are used to filter water in hydroelectric power plants.

• Turbines are only decorative elements in power plants.

Answer explanation

Turbines in hydroelectric power plants convert the kinetic energy of flowing water into mechanical energy. This mechanical energy is then transformed into electrical energy, making it essential for power generation.

Explain the factors that determine the energy output of a dam.

• The energy output of a dam is determined solely by the width of the dam.

• The energy output of a dam is influenced by the height from which water falls, among other factors.

• The energy output of a dam is constant and not influenced by any factors.

• The energy output of a dam is determined by the color of the water.

Answer explanation

The energy output of a dam is primarily influenced by the height from which water falls, as greater height increases potential energy. Other factors include water flow rate and turbine efficiency, making the correct choice accurate.

What is the relationship between dam height and energy production capability?

• Higher dams produce less energy due to increased water pressure.

• Higher dams have more potential energy due to gravity, producing more energy.

• Dam height does not affect energy production capability.

• Lower dams produce more energy because they release water faster.

Answer explanation

Higher dams store more water at greater heights, increasing potential energy due to gravity. This results in greater energy production when the water is released, making the correct choice that higher dams produce more energy.

Why is water flow important in hydroelectric power generation?

• It determines the amount of potential energy available.

• It affects the efficiency of the turbines only.

• It determines the amount of kinetic energy available to spin the turbines.

• It has no impact on the total energy produced.

Answer explanation

Water flow is crucial in hydroelectric power generation as it determines the amount of kinetic energy available to spin the turbines, which directly impacts the energy produced.