Significant flexible load potential for US grid finds Duke study

At a time of increasing power demand concerns in the US, a new study from Duke University has found significant potential for load integration onto the power grid, should flexibility measures be taken.

This is according to Rethinking Load Growth: Assessing the Potential for Integration of Large Flexible Loads in US Power Systems, from the university’s Nicholas Institute for Energy, Environment & Sustainability.

The study, which looked at 22 of the largest balancing authorities serving 95% of the country’s peak load, finds that gigawatts of new load could be added to the US grid in each balancing authority (BA) before total load exceeds what system planners are prepared to serve.

This is so long as the new load can be temporarily curtailed as needed.

US grid load and flexibility

Specifically, finds the study, 76GW of new load—equivalent to 10% of the nation’s current aggregate peak demand— could be integrated with an average annual load curtailment rate of 0.25% (i.e., if new loads can be curtailed for 0.25% of their maximum uptime).

Additionally, 98GW of new load could be integrated at an average annual load curtailment rate of 0.5%, and 126GW at a rate of 1.0%.

The five balancing authorities with the largest potential load integration at 0.5% annual curtailment are PJM at 18GW, MISO at 15GW, ERCOT at 10GW, SPP at 10GW, and Southern Company at 8GW.

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Commenting in a release was lead Author Tyler Norris, a Ph.D student at the Nicholas School of the Environment: “Our study demonstrates that existing US power system capacity—intentionally designed to handle extreme peak demand swings—could accommodate significant load additions with modest flexibility measures.

“Overall, the findings suggest that load flexibility offers a promising near-term strategy for regulators and market participants to more quickly integrate new loads, reduce the cost of capacity expansion and enable greater focus on the highest-value investments in the electric power system.”

According to the study, the average duration of load curtailment, would be relatively short, at 1.7 hours when average annual load curtailment is limited to 0.25%, 2.1 hours at a 0.5% limit, and 2.5 hours at a 1.0% limit. Nearly 90% of hours during which load curtailment is required retain at least half of the new load, meaning that less than 50% curtailment of the new load is required.

The study adds that the number of hours during which curtailment of new loads would be necessary per year, on average, is comparable to those of existing US demand response programmes.

Overall, says the study, their results suggest the power system is sufficient to accommodate significant constant new loads, so long as such loads can be safely scaled back during some hours of the year.

In addition, they underscore the potential for using flexible load as a complement to supply-side investments, enabling growth while mitigating the need for large expenditures on new capacity.

Rising power demand concerns

Citing the NERC’s 2024 Long-Term Reliability Assessment, the study says that aggregated US winter peak load is forecasted to grow by 21.5% over the next decade, rising from approximately 694GW in 2024 to 843GW by 2034.

The primary catalyst for these updated forecasts is the surge in electricity demand from large commercial customers, such as data centres.

While significant uncertainty remains following the release of DeepSeek, the sector is expected to account for the single largest growth segment.

Thus, they add, the immensity of the challenge underscores the importance of deploying every available tool, especially those that can more swiftly, affordably, and sustainably integrate large loads.

This is where flexibility could come in, where end-use customers can temporarily reduce their electricity consumption from the grid during periods of system stress by using on-site generators, shifting workload to other facilities, or reducing operations.

The study was coauthored by Tim Profeta, senior fellow at the Nicholas Institute and Associate Professor of the practice at the Duke University Sanford School of Public Policy; Dalia Patiño-Echeverri, Associate Professor at the Nicholas School of the Environment; and Adam Cowie-Haskell, a graduate student at the Nicholas School.