Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.

a. A dam is usually built at the site of hydroelectric power. As water accumulates, its potential power for producing electric power increases. As this water moves downstream from the dam, mostly through a fall, its kinetic energy is harnessed by turbines and converted to electric energy.

b. One factor is the height of the fall of the water from the dam. The higher the height the higher the kinetic energy of the water and hence can be converted to higher electric energy. The higher the number of coils of the turbine generator being rotated by the water, the higher the conversion to electric current.

c. One is impoundment. This type is the most common and involves the building of a dam to store water and later the water is released to turn turbines. The second type is diversion. This type does not require a dam. Some water is diverted from the main river to create a pen-stock that runs a turbine.

d. The advantage of hydroelectric power is that is is a clean energy source hence does not cause global warming. Global warming can have economic consequences. The operating cost of this type of plant is low hence the costs of electricity are able to be kept low for the consumers. 2 disadvantage is that creating a dam upstream causes a change in the physical and chemical characteristics of the river or water bodies affecting ecosystems. Another is that electricity is dependent on the water regime hence dependency is tied to climate.