BM start up

The BM start up service gives us on-the-day access to additional generation. The service is open to any Balancing Mechanism (BM) participants who expect to be unavailable within BM timescales of 89 minutes.

This service is made up of two elements:

  • BM start up; and
  • hot standby.

BM start up is the process of bringing the generating unit to a state where it is capable of synchronising with the system within BM timescales.

Hot standby holds the generating unit in this state of readiness. The unit will then either remain in hot standby until the end of its capability or be instructed to run via an offer in the BM.

BM start up instructions are issued via the Electronic Dispatch Logging (EDL) system. The instruction will specify a hot standby target time. This is the time at which the unit must be ready to synchronise within BM timescales of 89 minutes. If we wish to terminate the start-up instruction at any point prior to the hot standby target time, the instruction to cease will also be issued via EDL.


The number of instructions per provider is largely dependent on economics, with more economically efficient units being utilised ahead of more costly options.

Other factors that may also be considered when instructing BM start up are system constraints and the unit’s technical capabilities, such as the time taken to synchronise and minimum run time.

There were 336 instructions issued for BM start up in 2016. Find out more information about the units that were instructed to run on the System Operator Notification and Reporting (SONAR) system.