Connecting a large data center to the American electricity grid now takes years, and the companies building them have decided not to wait. Instead they are building their own power plants — behind the meter, on the same site as the computers, and in a growing number of cases wired to nothing else at all. The energy-data firm Cleanview, which tracks the trend from permit filings, utility records and satellite imagery, counts 59 such data centers with roughly 90 gigawatts of announced generation, more than a quarter of all planned US data-center capacity; 92 percent of it has been announced since the start of 2025. What was a curiosity two years ago, embodied by xAI trucking mobile generators into Memphis, is now a mainstream development strategy that nearly every hyperscaler is pursuing.

The equipment tells you how fast this happened. Heavy-duty combined-cycle gas turbines — the efficient choice for round-the-clock power — are effectively sold out: GE Vernova and its rivals Siemens and Mitsubishi Heavy Industries book delivery slots four to five years ahead, which is roughly the same wait as the interconnection queue the developers are trying to escape. So they buy whatever else generates electricity: aeroderivative turbines descended from aircraft and warship engines, fast-ramping reciprocating engines, refurbished industrial units, generators strapped to semitrucks. Cleanview found one developer placing a $1.25 billion order with a supersonic aircraft company that had never sold a power product. The arithmetic behind these choices is brutal and simple — an AI data center can earn $10 to $12 million per megawatt a year, so arriving early is worth almost any inefficiency. The consequence is that nearly every one of these plants runs on simple-cycle turbines, which vent their waste heat rather than recovering it in a steam cycle, and therefore emit more for each unit of energy than the plants that serve the grid. It is not a loophole; it is a purchase order.

What has not happened yet is most of the building. Of the roughly 90 gigawatts announced, Cleanview finds only about 2 gigawatts actually operating — a little over 2 percent, most of it xAI's — with another 1 percent under construction, 36 percent permitted, and some 60 percent still nothing but an announcement. The binding constraint has turned out to be neither money nor turbines but permission. Georgia halted construction on the state's first off-grid datacenter plant after finding its engines were installed without air permits. New Mexico blocked a pipeline that would have fuelled a 2.45-gigawatt on-site plant at a Stargate site. And in Texas, which leads the country in announced capacity, ERCOT has made clear that its "bring your own generation" pathway is not an exit from the queue: a generator co-locating with a large load must still file a full interconnection study, and the governor's August audit now requires every project to say exactly how much of its own power it is really building.

Two questions sit unresolved. The first is whether these campuses stay islanded. Several operators, Amazon among them, describe their off-grid plants as designed to connect to the grid later, which would turn a private generator into a market participant and raise every cost-allocation question the arrangement was meant to avoid. The second is what happens to the emissions. The plants are permitted for very large ceilings — Amazon's Pecos County campus alone is authorized for up to 33 million tons of carbon dioxide a year — and they are built to last decades, on a demand forecast that assumes AI's appetite keeps growing. A parallel fossil-fuelled power system is being assembled at speed, one air permit at a time, and the permits are where its shape is actually being decided.