PJM Interconnection, the operator of the largest electricity grid in the United States, has announced it will cut power to data centres and other large users during shortages after an auction to secure extra generating capacity fell short of what was needed. The move reflects growing strain on the grid from the rapid expansion of data centres, whose electricity consumption is projected to quadruple by 2035, and follows criticism of PJM's handling of new generation and demand in recent months.

The curtailments will not begin until June 2027 and will apply only to data centres of 50 megawatts or larger, with affected customers compensated and given advance notice ranging from 30 minutes to several days, similar to existing demand-response schemes used for large industrial users. PJM is holding a further auction for new capacity, but in the meantime many data centres are expected to invest in on-site power or rely on backup diesel generators, which are costlier and more polluting; federal rules cap such generator use at 50 hours a year for demand response. PJM's territory spans 67 million customers from Virginia to Illinois, and wholesale electricity prices there have nearly doubled over the past year, a rise its independent market monitor has largely attributed to data centre demand.