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Hydroelectricity - Coggle Diagram
Hydroelectricity
Primary energy source = Harnessing energy from the movement of water with a dam.
Water density = water flow rate x acceleration of gravity x head of the water
Drawbacks:
- Impact on fish population, water rights / politics, ecosystem changes, loss of silt, flooding of river banks, deforestation, start up costs
Hydroelectric dam design
Head change in water levels between hydro intake and hydro discharge point - a vertical height measured in metres.
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Factors influencing power production
- Quantity of water = More water falling through the turbine will produce more power.
- Degree of slope = The farther the water falls, the more power it has. Generally, the distance that the water falls depends on the size of the dam
Global patterns of hydropower reliance
- 936 GW, 19% of global electricity
Three gorges dam = LARGEST in the world, China.
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Benefits:
- Low carbon emissions
- High capacity
- Flood control
- Less intermittent (more reliable) than solar/wind
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Grand Ethiopian Renaissance Dam = water flow / rights concerns, provides 3x the current installed electric capacity in Ethiopia
Impacts of filling reservoir - need to submerge land, displaced human populations, submerge terrestrial plants and animals
Impacts:
Humans
- drowning
- Causes sediment buildup
Wildlife:
- Migratory and resident fish
- Methane emissions
- Anaerobic digestion
Climate change and the future
- Emissions occur from decomposing submerged animals / plants
- Poor water level management leads to increasing emissions
--Exposed plants take in CO2
--Submerged plants die / decay releasing methane
--Methane is 23x more potent than CO2
Run off river hydro
Differences with dam = Uses elevation changes to move water through penstock, diverts water and returns water to a stream
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