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What Are the Advantages & Disadvantages of Hydropower?

Hydropower, or hydroelectric power, is power that comes from the movement of water. According to the U.S. Energy Information Administration, in 2009, hydropower accounted for 7 percent of total U.S. electricity generation and 35 percent of generation from renewables. Hydropower has many advantages, but many of the implementations of hydropower, like hydroelectric dams and tidal power generators, have drawbacks -- the most notable being their negative impact on the environment.

Renewable Energy
- An advantage of hydropower is that the power is generated from the energy of moving water, and is thus renewable energy. Hydropower installations, like the Three Gorges Dam -- world's largest hydroelectric plant, at the time of publication -- and the Rance Tidal Power Station, passively generate huge amounts of electricity. Since many countries throughout the world have access to either ocean tidal energy or energy from rivers, hydropower is a form of renewable energy available to most of the world.
Land Alterations
- One of the often cited criticisms of hydropower installations is that they alter the natural landscape. Hydroelectric dams and tidal power installations block the flow of sediment and other debris, for instance, creating buildup and altering the marine ecosystem. Dams also create huge reservoirs, which submerge large areas of land that may be inhabited or have other value. The Three Gorges Dam is one example where about 1.4 million people were forced to move for the dam's construction to proceed.
High Power Output
- Water movement has the potential to produce huge amounts of power, dwarfing the power-generating capacity of other renewable energy sources. Companies are developing large, 10 megawatt (MW) wind turbines, for instance, that would be larger than any other wind turbines currently available. For comparison, the Three Gorges Dam can produce 18,200 MW at full capacity. The Rance Tidal Power Station can produce 240 MW at peak capacity, which is still significantly more than wind turbines.
Marine Wildlife
- Another disadvantage of hydropower installations is that they negatively impact marine wildlife, such as salmon. Dams or tidal power installations may temporarily impede salmon from reaching their spawning grounds or block them completely. Some small dams in the Pacific Northwest have been removed to better allow salmon to reach spawning grounds. Some fear other hydropower installations, like wave power generators, may disturb marine life, though the technology is too new and untested, at the time of publication, to know for sure.

Nature