The largest electrical grid operator in the United States, PJM Interconnection, has said it will cut power to large data centres and other big users during power shortages, starting in June 2027. The move follows an auction to add more generating capacity that fell short of demand.
The cuts will apply only to data centres of 50 megawatts or larger. Affected customers will be compensated under a demand response programme similar to those long used for manufacturers, and will receive advance notice of between 30 minutes and a few days, depending on forecast demand.
PJM's territory runs from Virginia to Illinois and covers 67 million customers. Over the past year, wholesale electricity prices have nearly doubled, and PJM's independent market monitor has attributed much of the increase to data centres. The grid operator is running another auction for new generating capacity.
The policy is likely to encourage new and existing data centres to set up their own on-site power sources. Those that do not will probably rely on backup generators, often diesel, which are costlier to run and more polluting. Federal rules allow such generators to be used for up to 50 hours per year for demand response events, and up to 100 hours including emergencies and maintenance.