Battery Energy Storage Systems (BESS): An Essential Tool for Managing the Electricity Grid
Electricity grid operators are constantly looking for new ways to store energy at scale to better manage the balance between supply and demand. This is where battery energy storage systems (BESS) come in. As a reliable, flexible and efficient source of energy storage, BESS can provide a range of services to support grid operations, making it a valuable tool for managing the electricity grid.
One of the key services BESS can provide is energy arbitrage. This involves charging the battery when energy prices are low and discharging during more expensive peak hours. By taking advantage of fluctuating electricity prices, BESS operators can generate income, while also reducing renewable energy curtailment. By charging the battery with low-cost energy during periods of excess renewable generation and discharging during periods of high demand, BESS can both reduce renewable energy curtailment and maximize the value of energy sold to the market. Additionally, BESS can be used to load-level by charging batteries during periods of excess generation and discharging during periods of excess demand to more efficiently coordinate the dispatch of generating resources.
Another important service BESS can provide is firm capacity or peaking capacity. During periods of high electricity demand, system operators need to ensure they have an adequate supply of generation capacity to reliably meet demand. While conventional generators like gas plants are typically used to meet this requirement, BESS can also be used to ensure adequate peaking generation capacity. This is particularly important in systems with a growing share of variable renewable energy (VRE) resources, as BESS can be paired with these resources to improve their capacity value and system reliability.
BESS can also provide operating reserves and ancillary services, which are needed to maintain reliable power system operations. These services function on different timescales, from sub-seconds to several hours, and require a rapid response time. BESS can rapidly charge or discharge in a fraction of a second, making them a suitable resource for short-term reliability services such as Primary Frequency Response (PFR) and Regulation. Additionally, appropriately sized BESS can also provide longer-duration services, such as load-following and ramping services, to ensure supply meets demand.
In addition to providing energy storage services, BESS can also help defer or circumvent the need for expensive upgrades to the transmission and distribution infrastructure. The electricity grid’s transmission and distribution infrastructure must be sized to meet peak demand, which may only occur over a few hours of the year. BESS can help defer or avoid the need for new grid investments by meeting peak demand with energy stored from lower-demand periods, thereby reducing congestion and improving overall transmission and distribution asset utilization. Moreover, BESS can be relocated to new areas when no longer needed in the original location, increasing their overall value to the grid.
Finally, BESS can support black start operations. During normal system conditions, large generators need an external source of electricity to perform key functions before they can begin generating electricity for the grid. However, in case of a major power outage, this external source may not be available. BESS can provide a source of electricity to these generators to get them started, helping to restore power more quickly after an outage.
In conclusion, BESS can provide a range of valuable services to support grid operations. From energy arbitrage to supporting black start operations, BESS can help improve system reliability and resilience, while also helping to integrate variable renewable energy resources into the grid. As the demand for clean and reliable energy continues to grow, BESS will play an increasingly important role in the future of the energy sector.
Applications of Utility-Scale Energy Storage:
|Application||Description||Duration of Service||Typically Valued in U.S. Electricity Markets?|
|Arbitrage||Purchasing low-cost off-peak energy and selling it during periods of high prices.||Hours||Yes|
|Firm Capacity||Provide reliable capacity to meet peak system demand.||4+ hours||Yes, via scarcity pricing and capacity markets, or through resource adequacy payments.|
|Operating Reserves||Primary Frequency Response||Very fast response to unpredictable variations in demand and generation.||Seconds|
|Operating Reserves||Regulation||Fast response to random, unpredictable variations in demand and generation.||15 minutes to 1 hour|
|Operating Reserves||Contingency Spinning||Fast response to a contingency such as a generator failure.||30 minutes to 2 hours|
|Operating Reserves||Replacement/Supplemental||Units brought online to replace spinning units.||Hours|
|Operating Reserves||Ramping/Load Following||Follow longer-term (hourly) changes in electricity demand.||30 minutes to hours|
|Transmission and Distribution||Replacement and Deferral||Reduce loading on T&D system during peak times.||Hours|
|Black-Start||Units brought online to start system after a system-wide failure (blackout).||Hours||No, typically compensated through other means.|