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Hydroelectric Power (Hydropower) - Coggle Diagram
Hydroelectric Power (Hydropower)
Core Principles & Concept
Definition
Most established and widely used renewable source
Water falls a vertical distance to drive a turbine
Energy Conversion
Potential Energy
(stored water) →
Kinetic Energy
(flowing water) →
Electrical Energy
(generator)
Power Equation
$$P = \rho \cdot g \cdot h \cdot Q$$
Variables
: rho is density, h is head/height, Q is volumetric flow rate in meters cubed per second
Sources
Water supply provided by annual rainfall/water cycle
Historical Development
Water Wheel
Initial use of kinetic energy from river flow
low efficiency ~ 20%
Overshot Wheel
Channels water, uses potential energy/height
Improved efficiency ~ 60%
Fourneyron Turbine
First modern design (metal/iron)
High efficiency (stepped up to ~80%)
Used smooth radial flow and guide vanes for control
System Configurations
Components
Dam
→
Reservoir
(Storage) →
Filter
→
Penstock
(Directs water) →
Control Valve
→
Turbine
→
Generator
Low Head (Run-of-the-River)
No storage (no reservoir)
Directly affected by flow rate (less reliable)
Medium/High Head (Dam Systems)
Inherent storage capability (reservoir)
Flow can be regulated to match demand (better control)
Pumped Hydro Storage (PHS)
Uses an upper and a lower reservoir
Pumps water up when tariffs/electricity are cheap (e.g., at night)
Provides quick response (e.g., 440 MW in 30 seconds) for grid stability
Turbine Types & Selection
Pelton
Suited for
High Head
(100-1000m) and
Low Flow
(1-10 meters cubed per second)
Used with a jet of water pointed at cups
Francis (Most Common)
Suited for
Medium Head
(10-100m) and
Medium Flow
(10-100 meters cubed per second)
Water funnels around the outside to central blades
Kaplan (Axial Flow)
Suited for
Low Head
(1-10m) and
High Flow
(100-1000 meters cubed per second)
Water flows vertically through propeller-like blades
Archimedes Screw
Micro-scale power generation
Coupled to a generator via a gearbox
Advantages & Disadvantages
Pros
Renewable
Emission Free
Reliable/Adjustable
(Base Load)
High efficiency (70%+)
Long Lifespan (e.g., Loch Slot, Scotland, opened 1949, still going strong)
Cons
Environmental Impact
(e.g., fish, destroying natural beauty)
Limited Plant Locations
High Initial Costs
(massive engineering projects)
Susceptible to Droughts
Flood Risk
(Dam failures)
Displacement of People
(e.g., Three Gorges, China)