| Typical discharge duration | 4–12+ hours | 1–4 hours | 4–12 hours | 4–24 hours | 4–15 hours | Hours to several days |
| Round-trip efficiency | 70–85% | 85–95% | 65–85% | 45–70% | 40–75% | 25–45% |
| Response speed | Seconds to minutes | Milliseconds to seconds | Seconds to minutes | Minutes | Seconds to minutes | Minutes to hours |
| Expected service life | 40–80 years | 10–20 years | 15–25 years | 25–40 years | 15–30 years | 10–30 years, depending on equipment |
| Cycle capability | Very high; suitable for daily operation | Approximately 3,000–10,000 cycles | 10,000–20,000+ cycles | High; limited mainly by machinery | High; depends on storage medium | Moderate; depends on conversion equipment |
| Energy and power scaling | Large-scale energy and power are closely linked to site design | Power and energy scale together through additional battery units | Power and energy can be scaled relatively independently | Suitable for large energy capacities; geological conditions are important | Flexible, depending on heat medium and application | Very suitable for seasonal or multi-day energy storage |
| Land and site requirements | High; requires suitable elevation, water and geology | Low to moderate; can be installed near load centers | Moderate; requires tanks and supporting systems | High; suitable caverns or storage vessels may be needed | Moderate; depends on heat demand and insulation | Moderate to high; requires production, storage and reconversion facilities |
| Safety considerations | Mature civil and operational safety practices | Requires thermal management, fire prevention and battery monitoring | Generally low fire risk; electrolyte management is required | Requires pressure, cavern integrity and air-quality management | Requires control of high temperatures and heat-transfer materials | Hydrogen leakage, ignition and high-pressure risks require strict controls |
| Environmental profile | Low operating emissions; major ecological impact can occur during construction | Low operating emissions; recycling and material supply chains are important | Low operating emissions; electrolyte treatment and recycling are required | Low operating emissions; site geology and construction impacts matter | Potentially low emissions, especially when using surplus renewable heat | Very low emissions when produced with renewable electricity; efficiency is lower |
| Best application in China | Bulk balancing, peak shifting and grid stability | Fast frequency response, renewable integration and short-duration peak shaving | Longer-duration renewable integration and frequent cycling | Large-scale, multi-hour storage where suitable geology is available | Industrial heat, district heating, solar-thermal and combined heat-and-power systems | Seasonal storage, industrial feedstock and hard-to-electrify sectors |
| Overall suitability | Best for proven, long-life bulk storage | Best all-round choice for short-duration flexibility | Strong option for durable long-duration cycling | Promising for large-scale long-duration storage | Best when electricity and useful heat can be integrated | Best for seasonal storage and cross-sector energy use |