The U.S. Department of Energy signed an emergency order on 12 October that allows PJM Interconnection to call on backup generators at data centers and other large loads from 13 to 16 October. Order No. 202-26-50, issued by Energy Secretary Chris Wright under section 202(c) of the Federal Power Act, answers a request PJM filed the day before. The backup units may be directed to run as a last resort before PJM declares an Energy Emergency Alert Level 3, the stage at which firm load is interrupted, or during one.
An Autumn Shortage, Not a Heat Wave
The figures in the order come from PJM's application. The grid operator forecast demand at around 111,500 MW or higher for 13 October and expected to be within 900 MW of its reserve margin on 14 October, with 61,591 MW of generation out of service across its footprint. The tightest areas are the BGE, PEPCO and Dominion zones. PJM puts it down to elevated demand, a high rate of planned plant maintenance in the autumn outage season, numerous planned transmission outages and firm export obligations, and it names transfer limits on a 500 kV line from the north and on a 345 kV tie with MISO, which has issued its own capacity advisory from 12 October. The American Public Power Association, reporting the order the same day, described it as a step to reduce the risk of blackouts in the mid-Atlantic.
The order covers backup resources of every kind - auxiliary, standby, directly connected, battery storage - whether or not they are synchronised to the grid, at data centers including hyperscale sites and at other large industrial and commercial customers. PJM may ask transmission owners and distribution companies to help customers bring the units online. Backup generation serving defense and homeland security sites, hospitals, first responders, air traffic control, 911 centers, water and wastewater plants and gas pipeline facilities is excluded, and a unit that runs under the order does not become a capacity resource.
What Happens to the Permit Hours
PJM asked to use backup generation regardless of environmental limits under federal, state or local law, and expects possible exceedances of permit limits on sulphur dioxide, NOx, carbon monoxide, ammonia and fuel throughput. DOE confines operation to the times and parameters PJM sets for reliability and states that emissions, run hours and fuel burned while the order is in force will not count toward rolling-average permit limits. Monitoring, reporting and recordkeeping still apply as far as practicable, PJM has to tell DOE every day which resources ran, and the units are back under their permits once the order expires. The order refers to the Secretary's letter of 22 January on backup generation in emergencies and to the orders issued during Winter Storm Fern.
Four Days on the Operator's Side
For the people who look after these sets, an order like this changes the job for a few days. A standby yard normally runs for its monthly exercise and the odd outage; under a grid call it may run for hours on a day nobody planned, and the questions become practical ones. Is the day tank topped up, is the main fuel store full, and how quickly can the supplier refill it if the run goes long. Who on site is allowed to accept the utility's request to transfer, and is the log ready to record every hour and every gallon for the daily report. On units with SCR, is there enough reagent for a long run, since the relief is limited in time and the record stays.
Noise is the part that reaches the neighbours. Whether a local noise ordinance falls under the relief is a question for the site's lawyer; a long daytime run will be heard either way, by people used to a short monthly test. We wrote about county codes catching up with generator yards in the Pima County and Bloomington item. An emergency order from Washington and a property-line limit from the county now apply to the same machines.
Sources: U.S. Department of Energy, Order No. 202-26-50, American Public Power Association, Microgrid Media