6.9: Hydroelectric Power Flashcards
Basics of hydroelectric energy generation
Kinetic energy of moving water spins the turbine/ mechanical energy which powers the generator. The water can either move with the natural current or tides, by falling vertically through a channel in a dam
Hydroelectric renewability
The largest renewable source of electricity globally
What do river dams allow?
- Enables operators to change the amount of water flowing through the channel in the dam which can increase or decrease electricity production
- Control the flow of water downstream which prevents seasonal floods due to high rainfall
2 Big Impacts of Dams
Flooding of ecosystems behind dams and sedimentation
Run of river system to electricity generation
Dams divert the current of a river through a man-made channel beside the river which turns the turbine to power the generator
Run of River System and Tidal Energy
Tidal power comes from tidal ocean flow from coastal areas
Doesn’t create a reservoir and uses the natural flow of the water to funnel to the turbine and go through electricity cycle. It is less impactful to surrounding ecosystems since no reservoir is formed and ecosystems behing dams aren’t flooded
Benefits of Run of River System
Doesn’t stop natural flow of sediments downstream like dams do
Cons of run of river system
Doesn’t generate nearly as much power and may be unavailable when river water levels are lower
Cons of reservoir
Reservoirs flood habitats behind dam (forests/wetlands are gone, river becomes a lake)/ loss of ecosystem services
* Prevents upstream migration of fish like salmon, that need to swim upstream to breeding ground
* Upstream becomes warmer, holding less oxygen
* Downstream loses sediments which are an important nutrient source, decreases water level, loses streambed habitat
Env Impacts of reservoris
FF combustion during dam construction, increased evap due to larger surface area of erservoir and methane released due to decomposition of organic matter in reservoir
Econ Impacts of reservoirs
Homes and businesses must be relocated due to reservoir flooding and construction is expensive (creates long term jobs), sediment buildup, loss of fishing revenue as salmon breeding is disrupted
Benfits of Hydro Dams
- No GHG emissions when producing electricity even though the initial construction requires machinery that emits GHGS
- Reservoirs and dams can be tourist attractions which generate recreation money
- Jobs are created to maintain the dam
- Nor air pollutants released during electricity generation
- Control of downstream seasonal flooding
