BESS Grid Services
Prerequisites
A battery energy storage system (BESS) at a California solar farm charges during midday surplus and discharges during the evening peak. It earns revenue not by generating electricity but by time-shifting it. Batteries on the grid do not just store energy; they provide services that spinning generators used to provide alone.
Grid-scale batteries provide four main services, each with different requirements. Frequency regulation: responding in milliseconds to second-by-second imbalances between supply and demand, injecting or absorbing small amounts of power to keep frequency at 60 Hz. Requires fast response but small energy (minutes of duration). Peak shaving: discharging during the highest-demand hours to reduce the need for expensive peaker plants. Requires 2-4 hours of duration. Solar/wind shifting: charging when renewable output exceeds demand and discharging when it falls short. Typically 4 hours of duration. Capacity reserve: standing ready to provide power if a generator trips offline. Requires guaranteed availability, not continuous operation.
Each service has a different value and a different optimal battery configuration. A frequency regulation battery might be 10 MW / 10 MWh (1-hour duration). A solar-shifting battery might be 100 MW / 400 MWh (4-hour duration). Matching the battery to the service determines whether the investment pays off.
Worked Example
A utility needs to replace a 200 MW gas peaker plant that runs 4 hours per day during evening peak.
- Size the battery. 200 MW x 4 hours = 800 MWh.
- The battery costs $250/kWh installed. Total: 800,000 kWh x $250 = $200 million.
Can this battery also provide frequency regulation during the other 20 hours?
Yes. When not peak-shaving, the battery can earn additional revenue from frequency regulation, stacking services. This revenue stacking is what makes battery economics work: one asset, multiple value streams.
BESS grid services are reshaping how grid operators balance supply and demand, substituting chemical storage for combustion.
A grid-scale battery provides frequency regulation. The key requirement for this service is:
Frequency regulation requires speed, not duration. Batteries excel at this because they can respond in milliseconds, far faster than gas turbines.
The answer is ALesson complete
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