Energy storage is the capture of energy produced at one time for use at a later time, balancing supply and demand across electrical, mechanical, thermal, and chemical media. In power systems it smooths the variability of renewable generation, provides grid services such as frequency regulation, and improves resilience. Technologies range from electrochemical batteries and pumped hydro to thermal and hydrogen storage.
Overview
- Energy storage decouples the timing of energy production from consumption. In electricity systems this is increasingly critical because renewable sources such as wind and solar are intermittent, while demand follows its own profile. Storage absorbs surplus generation and discharges it when needed.
- Beyond bulk shifting of energy, storage provides fast-acting grid services, defers transmission upgrades, and underpins the resilience of Infrastructure against outages.
Key aspects
- Storage media: electrochemical (lithium-ion, flow), mechanical (pumped hydro, flywheel), thermal, and chemical (hydrogen).
- Power versus energy ratings and round-trip efficiency.
- Duration classes: short, medium, and long-duration storage.
- Degradation, cycle life, and safety considerations.
- Grid services: frequency regulation, peak shaving, and reserve capacity.
Mechanisms
- Charge and discharge cycles controlled by power-electronic converters.
- Energy management systems scheduling storage against price and Demand Response signals.
- State-of-charge and state-of-health estimation for battery longevity.
- Aggregation into virtual power plants coordinated with the Smart Grid.
Applications
- Firming variable Renewable Energy output.
- Behind-the-meter storage for homes and businesses.
- Electric Vehicle batteries and vehicle-to-grid services.
- Microgrids and backup power for critical Infrastructure.