The 4-1-1 on Emergency Interruptible Load

The Emergency Interruptible Load Service (“EILS”) program pays participants including political subdivisions to be available to reduce demand in emergency load situations — that is, when energy is running perilously short on the grid. This is not a peak-load reduction program but rather serves as an emergency response to prevent rolling blackouts. Emergency situations have historically occurred infrequently in Texas, but may potentially occur at anytime, and in fact, may be more likely in “shoulder” months in which high demand is not anticipated and so generation is off-line for scheduled maintenance.

The EILS program is part of ERCOT’s multi-step strategy for handling these potentially serious shortage situations. Under ERCOT’s Level 1 emergency response, the organization dispatches all available generation, issues a media appeal, and attempts to acquire maximum available power across the direct current (DC) ties that connect ERCOT with adjacent grids. Under its Level 2A emergency response, ERCOT deploys Load Acting as a Resource (“LaaRs”), which is another form of interruptible service. EILS, ERCOT’s Level 2B emergency response, is triggered when the grid frequency drops to 60 Hz. (Dropping to frequencies much less than 60 Hz can pose a threat to grid stability.) When grid frequency goes below 59.8 Hz, ERCOT deploys its Level 3 emergency response, which is to shed firm load via rolling blackouts.

In order to be eligible to bid into the EILS program, a load resource must have at least 1 MW of load that can be curtailed with ten-minute notice at any time during the committed hours. ERCOT has divided the day into four periods for the purposes of the EILS program, which allows resources to bid for a specific time frame. The load resource must have 15-minute interval metering or other statistically valid samples of its load that are acceptable to ERCOT. The load resource must be represented by a Qualified Scheduling Entity (“QSE”), (the QSE must have operations capable of receiving verbal commands 24/7.) In the event of the program being deployed, ERCOT will notify the QSE starting the ten-minute period, and the QSE must notify the load resource. The resource must keep its committed load offline until it is released by ERCOT. After ERCOT has released a resource, it is required to return to service within ten hours.

There is no minimum clearing price in the EILS program. Load resources bid for a specific MW (must be at least 1 MW) for a specific time period (one of the four daily periods) for each contract period (three per year). If accepted, the resource receives payment for being available to curtail its load regardless of whether it is called upon to do so. The resource does not receive additional payment if it is called upon to curtail.

-- Pat Jackson