Hydroelectric+Power

= Energy By Dam =

http://ga.water.usgs.gov/edu/hyhowworks.html - water and coal method are similar - water used to turn turbine like steam used to turn turbine

- key to this system is the dam, which allows water to build up on one side of the turbine - the water will follow the path of least resistance through the intake, down the penstock and through the turbine - hydropower systems are more equiped to deal with hourly changes in power consumption through "pumped storage" or water reuse

http://ga.water.usgs.gov/edu/wuhy.html - 7% of U.S. energy produced by hydroelectric dams - 19% of world power (China leading) - the following graph shows the generation of power by water according to state with Idaho (most power is water-generated) leading the charge - about 1/3 of the world's potential for hydroelectricity has been used - hydropower iteself doesn't pollute water or air, but the facilities can change the water and land - operation of reservoir can change water temperature and flow, altering the habits of animals, especially fish - methane (a damaging greenhouse gas) can form and be released into the atmosphere - building a dam will probably require home relocation - most of the appropriate spots for dam location have already been built on - hydropower is better than burning coal or oil because there is no drilling, no burning and no waste-disposal problems -since 1980, building rates have declined (see graph below)

- free besides the expense of the technology and maintenance - pays for itself many times over - very little pollution as chemicals are not released from burning biofuels - relative to other sources of energy, hydropower has low maintanence costs - reliable and stable technology - reduced greenhouse gas emissions - completely renewable - as long as water is on Earth, other forms of life will be too - the water cycle keeps the reservoirs full and the operation running
 * Pros:**

- high investment costs - the technology is expensive - placement determined by rivers and man-made channels (extremely expensive) - dependent on precipitation - destruction of a huge amount of habitat (reservoirs and dams take up lots of space) - loss of fish passage up and down-stream - possible changes in water quality - displacement of local animal populations
 * Cons:**

Hoover Dam:
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Flosom Dam:
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