76 GW Without a New Power Plant: The Duke Study That Made Flexibility the Cheapest Megawatt

Almost every debate about powering data centers starts from the same assumption: a new load needs new generation, sized to its peak, and new transmission to deliver it. A report published on February 11 by Duke University's Nicholas Institute for Energy, Environment and Sustainability challenges that assumption with a simple question. How much new load could the existing US power system serve if that load agreed to reduce consumption during the small number of hours when the system is under the most stress?

Across 22 of the largest balancing authorities serving 95% of US peak load, the authors estimate that 76 GW of new load, about 10% of current aggregate peak demand, could be integrated with an average annual curtailment rate of 0.25%. Utilities and grid operators build enough capacity to meet the highest demand of the year plus a reserve margin, even though that peak occurs only for a handful of hours, usually on the hottest summer afternoons or the coldest winter mornings.

A constant new load, such as a data center that runs flat out around the clock, can use that headroom most of the time. The problem arises only in the peak hours, when there is no spare capacity left. The average curtailment event would be short: 1.7 hours at a 0.25% annual limit, 2.1 hours at 0.5% and 2.5 hours at 1%. A facility asked to shed half its load for two hours a few times a year can shift some computing work to other sites, defer batch jobs, or run on-site backup generation or batteries for that period.

The report ranks the balancing authorities with the largest potential at a 0.5% curtailment rate: PJM at 18 GW, MISO at 15 GW, ERCOT at 10 GW, SPP at 10 GW and Southern Company at 8 GW. Those are also the regions where data center demand is growing fastest. Aggregated US winter peak load is forecast to grow by 21.5% over the next decade, from about 694 GW in 2024 to 843 GW in 2034, according to NERC's 2024 Long-Term Reliability Assessment.