Renewable energy storage technologies are crucial for balancing supply and demand and ensuring a stable energy supply. Key technologies include:

1. **Batteries**: **Lithium-ion** and **solid-state batteries** store energy for short to medium terms, ideal for grid stabilization and electric vehicles.

2. **Pumped Hydro Storage**: Uses excess energy to pump water to a higher elevation, which can be released to generate electricity during peak demand.

3. **Compressed Air Energy Storage (CAES)**: Stores energy by compressing air in underground caverns, which is released to generate power when needed.

4. **Flywheel Energy Storage**: Stores kinetic energy in a rotating flywheel, providing rapid response and short-term energy storage.

5. **Thermal Energy Storage**: Stores excess thermal energy in materials like molten salt or phase-change materials, which can be used to generate electricity or provide heating.

These technologies help address the intermittent nature of renewable energy sources, improve grid reliability, and support the transition to a more sustainable energy system.