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Transcript of Hydroelectric Power
Flexibility - The electric power production can be adjusted quickly to adapt to the current energy demand.
Low Cost - As the costs of fossil fuels continue to rise hydroelectric power remain constant as it is almost immune to an increase in price. Operating costs are also very low.
Long service life - Most of hydroelectric power plants function for 50 - 100 years.
Low CO2 emissiones - No fossil fuels are burnt in the process of making the electric power. Ranked the most green way of making electricity by ExternE project.
Flood Controll - Large hydro dams can controll the flood helping those living down the stream. Disadvantages Ecosystem Damage - Damage to up and down river aquatic ecosystem. (Modern dams have fish ladders to allow fish to move like normal)
Loss of land - The damns result in large losses of land upstream, resulting in the loss of forests, marshland and grassland.
Methane Emission - The reservoirs produce a large quantity of methane. This happens because the plants in the flooded areas decay resulting in the formation of methane gas.
Relocation - People living at the site must be relocated to make room for the reservoirs. In February 2008 around 40 - 80 million people had to relocate due to dam constructions.
Failiure Risk - Large dams like any other large buildings are a subject to poor construction or terrorism. The dams are holding back large masses and a poorly constructed dam may colaps. During WWII large dams where great targets for military operations and terrorism. Conventional (Dams) The power comes from the potential energy of the dammed water. This drives a water turbine and generator. A large pipe known as the "penstock" delivers water to the turbine. Pumped-Storage This is a system used to meet high peak demands for electrisity. It works by moving water between reservoirs at different elevations. At low demand excess generation capacity is used to pump water into the upper reservoir, and then in the time for high demand the water is released back through a turbine. Run-of-the-river These are hydroelectric stations which are so small that they have no reservoir. Meaning that water running down the stream must be used instantaniously to produce electricity. Tide This system uses the daily rise and fall of the water level. This is a good way of producing electricity as tidal movement can be predicted by science. Underground This system uses the large natural height differences between two waterways. For example a water fall. A tunnel is constructed undeground which transports water from the high to the low, turbines and generators are built into the ground to preserv the energy created. P = phrgk P - Power (watts)
p - Density of water (~1000 kg/m^3)
h - height (meters)
r - flow rate (Cubic meters per second)
g - acceleration due to gravity (9.81 m/s^2)
k - Coefficient of efficiency (0-1) p - ~1000 kg/m^3
h - 15 meters
r - 2.8 Cubic meters per second
g - 9.81 m/s^2
k - 0.6 P = (1000) x (15) x (2.8) x (9.81) x (0.6) Power = 247212 Watts ~ 10 Normal Households