How do flywheels compare to other energy storage technologies

Key Comparisons

1. Energy Storage Mechanism

Flywheels: Mechanical (kinetic energy via high-speed rotation).
Batteries: Chemical (electrochemical reactions).
Compressed Air: Mechanical (compressed air’s internal energy).
Pumped Hydro: Mechanical (gravitational potential energy via water elevation).

2. Efficiency

Flywheels: ~85% round-trip efficiency.
Batteries: 85–95% (lithium-ion).
Compressed Air: 40–70% (improved with thermal storage).
Pumped Hydro: 70–85%.

3. Cycle Life

Flywheels: >50,000 cycles (minimal degradation).
Batteries: 2,000–5,000 cycles (lithium-ion).
Compressed Air: 10,000+ cycles (mechanical wear limits).
Pumped Hydro: 30,000+ cycles.

4. Energy Density & Duration

Flywheels: Low energy density; suitable for short-term storage (<30 minutes).
Batteries: Moderate-high density; hours of storage.
Compressed Air: Moderate density; hours to days.
Pumped Hydro: Low density; 6–20+ hours.

5. Response Time

Flywheels: Milliseconds (ideal for frequency regulation).
Batteries: Milliseconds to seconds.
Compressed Air: Minutes.
Pumped Hydro: Minutes to hours.

6. Environmental Impact

Flywheels: Non-toxic materials (e.g., steel, composites); recyclable.
Batteries: Toxic electrolytes (lithium, cobalt); recycling challenges.
Compressed Air: Minimal toxicity; site-specific geological requirements.
Pumped Hydro: Ecosystem disruption.

7. Cost Considerations

Flywheels: Low LCOS (3.8¢/kWh for microgrids over 25 years).
Batteries: Higher LCOS (11¢/kWh).
Compressed Air: Lower upfront costs than pumped hydro.
Pumped Hydro: High capital costs but low operational expenses.

8. Lifespan

Flywheels: 15–30+ years (minimal maintenance).
Batteries: 5–15 years (degradation accelerates with cycling).
Compressed Air: 20–30 years.
Pumped Hydro: 40–60 years.

Use Case Summary

Flywheels: Frequency regulation, grid stabilization, UPS.
Batteries: Residential storage, EVs, medium-duration grid support.
Compressed Air: Large-scale grid storage (multi-hour needs).
Pumped Hydro: Long-duration baseload support.

Flywheels excel in high-power, rapid-response applications, while batteries and mechanical storage dominate longer-duration needs. Environmental and cost factors further differentiate their suitability.

Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-do-flywheels-compare-to-other-energy-storage-technologies/