This week, power lines went down in a Washington, D.C., suburb. Typically, the grid only takes a few seconds to recover from such an event. But the process took more than 10 minutes, as more than 3 gigawatts of data centers lost power at about the same time.
The event caused voltage spikes on the PJM power grid from Northern Virginia to Chicago, according to data collected by Ting Labs, a startup that operates IoT sensor networks from people’s electrical outlets.
The incident did not cause a power outage, but it did cause lights to flicker throughout the area. This incident demonstrated the impact data centers have on the power grid. Experts believe this effect will become more frequent.
Northern Virginia, within PJM’s territory, has the highest concentration of data centers in the world.
“This is the canary in the coal mine,” Ricardo de Azevedo, CTO of ON.Energy, told TechCrunch. These types of events involving large loads such as data centers are “occurring more and more,” he added.
This incident mirrors what happened two years ago, also on PJM’s power grid, and could be a harbinger of something bigger if data centers are not built to better handle power interruptions. PJM Interconnection manages the electrical grid from New Jersey to Illinois and serves 67 million customers, making it the largest electrical grid operator in the United States.
When power lines went out this week, data centers switched to backup power, wiping out about 3.1 gigawatts of load in about 30 seconds, according to PJM data. The grid appeared to recover somewhat, but the additional load soon dropped. At its peak, PJM’s power grid delivered an additional 3.49 gigawatts of power. It took another 11 minutes to stabilize. According to Reuters, the disconnected data centers accounted for about 3% of PJM’s total demand at the time.
A few percentage points may not sound like much, but the power grid must operate in near-perfect balance, with supply and demand exactly matching. Otherwise, the voltage may drop or spike. The grid and the devices connected to it can tolerate small fluctuations, but if they become too large, failsafes within the grid or within individual facilities kick in and disconnect.
When a data center in Northern Virginia detected fluctuations due to power line failures, it switched to backup power and removed the load from the grid. As more data centers made the switch, more load was removed from the grid. What started as a relatively small decrease in supply turned into an even larger decrease in demand, causing supply to surge and light bulbs to flicker.
Most data centers make instantaneous decisions, and the one that was disconnected this week appears to be no exception. When the brownout reached them, they all decided to disconnect from each other within seconds, Ali Zain Banatwala, senior market model specialist at Independent Power System Operator, told TechCrunch.
“We need to find a way to sequentially disconnect or reconnect these loads that are located next to each other,” he said. A more orderly process will allow grid operators to develop more robust procedures in advance.
Or you can build your data center to absorb the disruption and not turn your back on it. One of the startups, ON.Energy, is working on products to help data centers and power grids survive events like the one that occurred this week.
The company has developed an uninterruptible power supply for an entire data center campus that covers not only servers but also chillers and other equipment. The company essentially hides its data center behind a battery bank connected to advanced power conversion equipment. The grid “sees” one consistent, well-behaved load, rather than the peaks and valleys of individual parts of the data center. ON.Energy’s systems allow data centers to ramp up and down compute workloads, including AI training, without disrupting the grid.
Perhaps more importantly, it also means data centers can absorb power fluctuations from the grid. Rather than disconnecting from the grid, ON.Energy’s system can use excess power to charge batteries and power servers when flow rates drop. Additionally, it can follow the lead of the grid within milliseconds, preventing sags and surges like the ones that caused problems for PJM this week.
De Azevedo said ON.Energy currently has a total of 3 gigawatts worth of systems installed across four different data center campuses.
Power grid managers have also noticed this problem.
ERCOT, for example, will need massive data center loads to “survive” the disruption, de Azevedo said.
But the clock is ticking. This week’s mass disconnection was twice the size of a similar event in 2024, when 60 data centers were simultaneously disconnected and 1.5 gigawatts of load was pulled from the power grid. At the time, data centers accounted for about 6% of PJM’s load, according to Synapse Energy Economies. By 2040, they are expected to account for 24%. If the problem is not resolved soon, things can get worse.
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