BESS operates by storing electrical energy in rechargeable reserves.
Battery energy storage systems (BESS) are becoming pivotal in the revolution happening in how we stabilize the grid, integrate renewables, and generally store and utilize electrical energy. BESS operates by storing electrical energy in rechargeable reserves, which can later be discharged to power local or grid-scale demand. Perhaps most importantly, these battery-held reserves are ready to switch into grid supply quickly, as demand or frequency/voltage instability trigger them automatically.
Operational and commercially available BESS setups come in various types, each with unique characteristics that are better suited to particular applications, environments, or operational differences. Although many technological details in the control and battery management systems (BMS) are different, at their core, BESS are classified by the nature of the cell/battery systems they employ. The different types of BESS are listed below:
- Lithium-based systems: These encompass lithium-ion cobalt oxide (LiCoO2); lithium-ion nickel cobalt aluminum oxide (NCA); lithium-ion nickel manganese cobalt oxide (NMC); lithium-ion iron phosphate (LiFePO4); lithium titanate (LTO); and solid-state lithium-ion. Together these are the most common class of BESS due to their high energy density, long deep-cycle life, and relatively low maintenance requirements. They are versatile across all of the operational modes that BESS encounters.
- Flow batteries: Store energy in liquid electrolytes contained in external tanks. They benefit from scalability and long cycle life, making them optimal for large-scale permanently installed energy storage applications. Vanadium redox flow batteries (VRFBs), for example, offer very long duration storage and flexibility in power output.
- Lead-acid batteries: Have been used for energy storage for over 150 years and are appreciated for their low-cost robustness. Although they offer considerably lower energy density and shorter cycle life compared to more current technologies, they remain relevant for certain applications, such as backup UPS (uninterruptible power supply) power systems and smaller (typically domestic) off-grid installations.
- Sodium-sulphur batteries: Operate at high temperatures and use molten sodium and sulphur as power storage media. They can have high energy density and are well adapted to large- scale applications, such as grid stabilization and renewable/junk-power integration.
- Supercapacitors (or ultracapacitors): Store energy as electrostatic charge and offer the highest possible charge and discharge ability. Although they (currently) have lower energy density than batteries, they excel in applications requiring frequent cycling, such as short- term ballast for smoothing out brief power fluctuations in microgrids. Source