How scientists turn lakes into giant batteries

TED-Ed

Current Largest Battery Systems

World's biggest lithium-ion battery (2020): Southern California power grid
- 250 million watts capacity
- Powers ~250,000 homes
- Duration: only 1 hour
Actual world's biggest battery: pair of lakes (pumped hydro storage)
- 300 meter height difference between lakes
- Stores energy via gravitational potential energy
- 6 giant turbines generate 3 billion watts for 10 hours
- Uses billions of liters of water pumped uphill

Battery: stores energy + releases on demand
Lithium-ion mechanism:
- Energy stored in lithium ions
- Ions separated from electrons, rejoined at other end
- Creates new molecule with lower energy

Pumped hydro storage:
- Requires specific geography
- Takes up extensive land
- High upfront construction costs
Lithium-ion batteries:
- Great for low-power applications
- Must be huge/heavy for large energy storage
- Limited heavy metal resources
- Mining causes environmental damage

Skyscraper battery (gravity-based):
- Solar-powered crane stacks blocks in tower
- Gravity pulls blocks down at night
- Powers generators through gravitational energy
- Some early setbacks reported
Molten salt batteries:
- Heating salts until melted using excess energy
- Stored molten salt boils water on demand
- Steam powers electricity-generating turbines
Bio-batteries:
- Made from paper, powered by bacteria
- Activated by human spit
- Bacteria metabolize glucose → release electrons
- Specific bacteria species transfer electrons outside cells
- Complete electrical circuit
- Won't power cities/houses but eliminate waste/cost concerns

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