Ancillary Services

Ancillary Services Markets

The NYISO administers competitive markets for key ancillary services that are required to support the power system. The two most important are reserves and regulation.

By selecting units with the lowest total production cost to provide energy, reserves, and regulation, the NYISO minimizes the cost of serving load.

Reserves and regulation are typically provided by generators; however the NYISO has opened these markets to include loads (demand-side providers).

Key Energy Terms


Resources available to provide fast ramping power in the event of a unit or line trip. Reserve resources can either be spinning (on-line with additional ramping ability) or non-spinning (off-line, but able to start and synchronize quickly). The NYISO maintains varying levels of reserves in different parts of the state.


To keep load and generation in constant balance, the NYISO relies on regulating resources which can quickly adjust their output/consumption in response to constantly changing load conditions.