AP Environmental Science : Hydroelectric Energy

Study concepts, example questions & explanations for AP Environmental Science

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Example Questions

Example Question #1 : Dams

All of the following are potential benefits to dams EXCEPT __________.

Possible Answers:

Clean electricity generation

Flood control

Sedimentation buildup

Recreation opportunities from the resulting lake

Water level management

Correct answer:

Sedimentation buildup

Explanation:

Dams can be huge boons to local economies, and are a landmark of human engineering and achievement; however, they do carry serious consequences to the natural environment. They lead to sediment buildup, which hurts the flow of nutrients downstream, ruins the natural riverscape, and can cause the area behind the dam to become more shallow.

Example Question #2 : Dams

All of the following are drawbacks to dams EXCEPT __________.

Possible Answers:

Destruction of surrounding farmland

Local inhabitants may be forced to move

Increased air pollution

Interruption of migration patterns among fish

Habitat alteration

Correct answer:

Increased air pollution

Explanation:

Dams carry numerous drawbacks, but one benefit of dams that they do not increase air pollution. Hydroelectric power is considered to be one of the cleanest forms of energy.

Example Question #11 : Energy Sources And Production

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

Possible Answers:

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

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

Dams can contribute to flooding and resulting property damage. 

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

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

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 #2 : Hydroelectric Energy

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:

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

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

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.

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

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.

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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