What requirement does NERC have for the percentage of Contingency Reserve that must be frequency responsive?

NERC's stipulation regarding Contingency Reserves works to enhance the reliability of the grid as it manages unexpected disruptions. In the context of frequency response, which is crucial for maintaining system stability after disturbances, it is important to understand that NERC does not impose a specific requirement regarding the percentage of Contingency Reserve that must be frequency responsive.

This lack of a mandated percentage signifies that while having frequency-responsive reserves can enhance the overall robustness of the grid and assist in maintaining reliability, there is no set threshold percentage that entities must adhere to. Operators have flexibility in how they configure their reserves, allowing them to take into account various operational contexts, geographical considerations, and resource availability. Thus, the concept of a fixed percentage requirement does not align with NERC's current approach to contingency reserves, hence the correct answer reflects this reality.