AP Environmental Science : Advantages and Disadvantages of Hydroelectric Energy

Study concepts, example questions & explanations for AP Environmental Science

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Example Questions

Example Question #23 : Energy Production And Usage

Which of the following is NOT an adverse affect of building dams to generate hydro-electric power?

Possible Answers:

Many fish populations (including salmon and trout) are decimated because dams restrict access to essential habitat. 

Animals that rely on fish as sustainance may begin to decline because the dam has permanently altered fish habitat. 

Dams often change the current and width of a watershed, altering the riparian ecosystem. 

Dams can contribute to flooding and resulting property damage. 

The energy required to operate and maintain the dam is often equal to the energy produced by the dam. 

Correct answer:

The energy required to operate and maintain the dam is often equal to the energy produced by the dam. 

Explanation:

The energy output from a hydro-electric dam is substantial enough to result in most of America's major rivers being damned. The more pressing issues that these damns cause are changes to the aquatic ecosystem and restriction of movement for migratory fish species. 

Example Question #24 : Energy Production And Usage

Hydroelectric energy composes a significant portion of the U.S. energy grid and is a low-emission, renewable form of energy. Which of the following would be a substantial issue with expanding hydroelectric energy production?

Possible Answers:

With the pressing issue of climate change and changes in precipitation, it is unclear how much energy current hydroelectric dams can provide in the future, let alone how much energy dams built in the future could provide.

Most if not all rivers capable of generating substantial hydroelectric energy have already been dammed and are working at high capacity.

There is currently a federal ban on the construction or development of future hydroelectric dams to protect fish populations.

The reported amount of electricity generated by hydroelectric dams is actually an inflated figure derived from theoretically running at full capacity and is not realistic.

The amount of energy invested in hydroelectric is about equal to the amount of energy harnessed from the process.

Correct answer:

Most if not all rivers capable of generating substantial hydroelectric energy have already been dammed and are working at high capacity.

Explanation:

While there are federal wetland conservation laws geared at protecting aquatic habitat, there is currently no federal ban on constructing hydroelectric dams, and the returned energy investment for hydroelectric is quite substantial. The dominant issue with expanding hydroelectric energy production is that in the U.S., we have dammed most if not all of the significant energy-producing water bodies. Further expansion of hydroelectric power will not yield as much energy as the current dams operating in the U.S.

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