DE can provide the services necessary for the efficient operation of the power grid. Ancillary services are those necessary to support the transmission of power and include such categories as: voltage support/reactive power, regulation of load imbalances, operating reserves (spinning and non spinning), backup supply, blackstart capability.
The ancillary benefits offered by DE are well documented in a February 2007 US Department of Energy document on the potential benefits of DE.
DE can provide voltage support to exisiting grid infrastructure thereby reducing losses, saving money and eliminating unnecessary pollution. Sending reactive power over transmission lines from central generators creates additional congestion on the system. If the same reactive power is supplied locally it frees up useful grid capacity for real power transfer from generator to load. The dynamic nature of DE as a supplier of reactive power also makes DE more valuable compared to other static sources often relied upon by utilities to supply reactive power such as synchronous condensers, static VAR systems etc.
Because many DE technologies can be kept in idle mode and brought up to full capacity in a short period of time they are ideal candidates for providing spinning reserve, non spinning reserve and blackstart capability. DE resources aggregated together could effectivley play the same role as even very large plants sometimes used to provide the necessary redundancy in the system in times of emergency or unplanned maintenance.