hydropower的好處和壞處,,,20分!!!!!!

Hydropower offers advantages over other energy sources but faces unique environmental challenges.

1. Advantages
1.1 Hydropower is a fueled by water, so it's a clean fuel source. Hydropower doesn't pollute the air like power plants that burn fossil fuels, such as coal or natural gas.

1.2 Hydropower is a domestic source of energy in some countries (say, produced in the United States)

1.3 Hydropower relies on the water cycle, which is driven by the sun, thus it's a renewable power source.

1.4 Hydropower is generally available as needed; engineers can control the flow of water through the turbines to produce electricity on demand.

1.5 Hydropower plants provide benefits in addition to clean electricity. Impoundment hydropower creates reservoirs that offer a variety of recreational opportunities, notably fishing, swimming, and boating. Most hydropower installations are required to provide some public access to the reservoir to allow the public to take advantage of these opportunities.

1.6 Other benefits may include water supply and flood control.


2. Disadvantages
2.1 Fish populations can be impacted if fish cannot migrate upstream past impoundment dams to spawning grounds or if they cannot migrate downstream to the ocean. Upstream fish passage can be aided using fish ladders or elevators, or by trapping and hauling the fish upstream by truck. Downstream fish passage is aided by diverting fish from turbine intakes using screens or racks or even underwater lights and sounds, and by maintaining a minimum spill flow past the turbine.

2.2 Hydropower can impact water quality and flow. Hydropower plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian (riverbank) habitats and is addressed using various aeration techniques, which oxygenate the water. Maintaining minimum flows of water downstream of a hydropower installation is also critical for the survival of riparian habitats.

2.3 Hydropower plants can be impacted by drought. When water is not available, the hydropower plants can't produce electricity.

2.4 New hydropower facilities impact the local environment and may compete with other uses for the land. Those alternative uses may be more highly valued than electricity generation. Humans, flora, and fauna may lose their natural habitat. Local cultures and historical sites may be impinged upon. Some older hydropower facilities may have historic value, so renovations of these facilities must also be sensitive to such preservation concerns and to impacts on plant and animal life.

the hydropower is a clean the power but　it's expensive

advantage
it is renewable energy source which would not be used up.
reduce the reliance on fossil fuel
produce less pollutants
solve flooding problem
disadvantage
building dam is costly
damge the ecosystem
the conservation of dam is also costly
the supply of electricity would not be constant wherever there is drought, flooding and other extremely weather

In addition to the problems mentioned above, there is a major problem about the foundation construction. If your "hydropower" refers to building a a big dam to retain a huge amount of water, the potential risk is that the rock stratum right under the dam will got a very huge bearing/compressive stress. Some earthquake scientists believe such a high stress could simulate earthquake to happen. It is because whether an earthquake can happen depending on how much stress “stored” in the rock.