As noted in Part 1 of this blog (last week), a new report, “Rethinking Load Growth: Assessing the Potential for Integration of Large Flexible Loads in U.S. Power Systems,” published by Duke University’s Nicholas Institute for Energy Environment & Sustainability,” noted that rapid U.S. load growth (driven by unprecedented electricity demand from data centers, industrial manufacturing, and electrification of transportation and heating), is colliding with barriers to timely resource expansion.

In Part 1, we looked at the challenges. Here, we look at some options.

To support evaluation of potential solutions, the study presented an analysis of the existing U.S. electrical power system’s ability to accommodate new flexible loads. The analysis, which encompassed 22 of the largest balancing authorities serving 95 percent of the country’s peak load, provided a first-order estimate of the potential for accommodating such loads with minimal capacity expansion or impact on demand-supply balance.

“Specifically, we estimate the gigawatts of new load that could be added in each balancing authority (BA) before total load exceeds what system planners are prepared to serve, provided the new load can be temporarily curtailed as needed,” said the report. “This serves as a proxy for the system’s ability to integrate new load, which we term curtailment-enabled headroom.”

Key results included:

1 – 76 GW of new load, equivalent to ten percent of the nation’s current aggregate peak demand, could be integrated with an average annual load curtailment rate of 0.25 percent (i.e., if new loads can be curtailed for 0.25 percent of their maximum uptime).

2 – 98 GW of new load could be integrated at an average annual load curtailment rate of 0.5 percent, and 126 GW at a rate of one percent.

3 – The number of hours during which curtailment of new loads would be necessary per year, on average, would be comparable to those of existing U.S. demand response programs.

4 – The average duration of load curtailment (i.e., the length of time the new load is curtailed during curtailment events) would be relatively short, at 1.7 hours when average annual load curtailment is limited to 0.25 percent, 2.1 hours at a 0.5% limit, and 2.5 hours at a one percent limit.

5 – Nearly 90 percent of hours during which load curtailment is required retain at least half of the new load (i.e., less than 50 percent curtailment of the new load is required).

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

Overall, these results suggest that the U.S. power system’s existing headroom, resulting from intentional planning decisions to maintain sizable reserves during infrequent peak demand events, is sufficient to accommodate significant constant new loads, provided such loads can be safely scaled back during some hours of the year. In addition, they underscore the potential for leveraging flexible load as a complement to supply-side investments, enabling growth while mitigating the need for large expenditures on new capacity.

The report went on to add: “We further demonstrate that a system’s potential to serve new electricity demand without capacity expansion is determined primarily by the system’s load factor (i.e., a measure of the level of use of system capacity) and grows in proportion to the flexibility of such load (i.e., what percentage of its maximal potential annual consumption can be curtailed).

The analysis covered in the full paper did not consider the technical constraints of power plants that impose intertemporal constraints on their operations (e.g., minimum downtime, minimum uptime, startup time, ramping capability, etc.) and did not account for transmission constraints. “However, it ensures that the estimate of load accommodation capacity is such that total demand does not exceed the peak demand already anticipated for each season by system planners, and it discounts existing installed reserve margins capable of accommodating load that exceeds historical peaks,” said the report. “It also assumes that new load is constant throughout all hours.”

The report went on to add that its analysis should not be interpreted to suggest the United States can fully meet its near-and medium-term electricity demands without building new peaking capacity or expanding the grid. “Rather, it highlights that flexible load strategies can help tap existing headroom 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,” said the report.

This full paper itself covers background on the opportunities and challenges to integrating large new data centers onto the grid.

As noted earlier, it explores how “load flexibility” can accelerate interconnection, reduce ratepayer costs through higher system utilization, and expand the role of demand response, particularly for AI-specialized data centers. Next, it details the methods and results for estimating curtailment-enabled headroom, highlighting key trends and variations in system headroom and its correlation with load factors across regions. The paper concludes with a brief overview of key findings, limitations, and near-term implications.