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Hydroelectric Power HEP :potable_water: - Coggle Diagram
Hydroelectric Power HEP
:potable_water:
The gravitational potential energy of rainwater that lands on upland areas
Can be harnessed as kinetic energy as it flows downhill
Practical exploration depends upon:
a large enough volume of water being available
suitable topography
that creates a high water pressure or high flow velocities
Kinetic energy has been used for thousands of years to provide mechanical power
More recently for electricity
Water wheels replaced by turbines
Ideal Location
:world_map:
Large water catchment area
High total rainfall - evenly distributed throughout the year
Low water turbidity
Impermeable bedrock beneath the reservoir
Low seismic activity
Suitable topography - narrow exit to a large basin
No serious land use conflicts
Close to consumers or electricty grid
Reduce transport costs
Environmental Impacts
:evergreen_tree:
Building the infrastructure impacts the environment through the creation of the reservoir and changes to flowing in and out :warning:
Reservoir Creation
:female-construction-worker::skin-tone-2:
Dam construction requires large amounts of material :mountain:
Rock
Sand
Gravel
Cement
Extraction, processing, transport requires energy :oncoming_bus:
Access roads will be required :car:
Reservoir
:sweat_drops:
Floods land :forbidden:
Loss of wildlife habitats :tanabata_tree:
Loss of farmland :pig2:
Loss of homes :house_buildings:
Provides area of static water :forbidden:
Suspended soilds/dead organic matter
Sink
Carried by river
Decomposition produces anerobic conditions
Releases methane gas
Positive impacts :green_heart:
Provides a new habitat for aquatic life
Impacts on the river
:desert_island:
Sedimentation can reduce turbidity downstream
Replenishment of nutrients onto flood plain around river
Natural flow fluctuations are replaced by the water flow that is controlled by the power station operators :person_with_blond_hair::skin-tone-4:
May involve a constant flow rate to produce the maximum power output
The reservoir stores surplus water when the flow rate of the river upstream is high
Some HEP stations are used to meet peaks in demand
Water flow will vary greatly
The impact of changes in flow rate depend upon the difference between natural and new flow regimes
Flow Regime
:large_blue_circle:
Seasonal flow extremes between wet and dry seasons
Constant flow
Dry season sandbanks used by nesting birds/turtles are lost
The loss of periods of high flow allows sediments to build up so gravel fish spawning sites are lost
Loss of high river levels downstream
Stops seasonal flooding of the surrounding land
Essential for plants, breeding fish, other aquatic species
Constant flow
Sudden flow increases
Increased turbidity caused by high flow rate
Makes it difficult for fish eating birds to see food
Reduced light penetration
Photosynthesis is more difficult
Species that cannot resist high flow rates may be washed away
Dam and reservoir divide the river into two sections
Prevents the movement of aquatic species
Salmon/Sturgeon cannot move upstream to spawn
Aquatic species that live in flowing water
Platypus
May not be able to pass the dam
Become isolated
New Technologies
:desktop_computer:
Low head turbines
:arrow_heading_down:
Some new developments allow increased use of low-head locations
Water drops a short distance
Waterwheels
:ferris_wheel:
Less efficient than turbines :red_cross:
Do not suffer from screen blockages :heavy_check_mark:
Leaves/litter
Kaplan Turbines
:studio_microphone:
Axial flow turbines with blades
Can be rotated to allow for variations in water flow
Harness up to 90% of the kinetic energy in flowing water
Helical Turbines
:muscle:
Similar to Archimedes screws
Used in several ancient civilizations to raise water
Turned by water flowing down the screw to generate electricity
High efficiency
Can use high turbidity water without being damaged :check:
Windsor Castle, Berkshire
Almost all electricity is generated by two helical turbines
Fish can carried down without being harmed :check:
Micro-hydro schemes
:microscope:
Small scale projects
Usually used by small rural communities
Enviro impact of damming has restricted use of HEP
Micro divert some of the river to turn the turbines
Do not create a barrier
Large HEP schemes
:globe_with_meridians:
Constructed in many countries with expanding industrial economies
China
Brazil