Sam Altman’s OpenAI will devour as much power as New York City and San Diego combined

Sam Altman and his partners say their next wave of AI data centers will consume electricity on a scale that rivals two major American cities at peak strain—a single project using more energy each day than both combined.

Andrew Chien, a computer science professor at the University of Chicago, called the announcement a “seminal moment,” one he has long anticipated.

“I’ve been a computer scientist for 40 years, and for most of that time computing was the tiniest part of our economy’s power use,” Chien told Fortune. “Now, it’s becoming a large share of what the whole economy consumes.”

He described the shift as both thrilling and troubling.

“It’s scary because … now [computing] could be 10% or 12% of the world’s power by 2030. We’re coming to some seminal moments for how we think about AI and its impact on society.”

This week, OpenAI revealed a plan with Nvidia to construct AI data centers consuming up to 10 gigawatts of power, with another 17 gigawatts already in progress. That’s comparable to the electricity needs of New York City in summer—about 10 gigawatts—and San Diego during the 2024 heat wave, which required more than five gigawatts. Experts noted the scale approaches the combined demand of Switzerland and Portugal.

“It’s pretty amazing,” Chien said. “A year and a half ago, they were talking about five gigawatts. Now they’ve upped the ante to 10, 15, even 17. There’s an ongoing escalation.”

Cornell University professor Fengqi You, who studies energy systems and AI, echoed that view: “Ten gigawatts is more than the peak power demand in Switzerland or Portugal. Seventeen gigawatts is like powering both countries together.”

Altman broke ground this week on one of the projects in Texas, where the power grid typically runs at about 80 gigawatts.

“So you’re talking about an amount of power that’s comparable to 20% of the entire Texas grid,” Chien said. “That’s for all the other industries—refineries, factories, households. It’s a crazy large amount of power.”

Altman has justified the massive expansion as essential to meeting AI’s explosive growth.

“This is what it takes to deliver AI,” he said in Texas, pointing out that usage of ChatGPT has increased tenfold in the past 18 months.