Walmart signed its first-ever nuclear power deal this week, with Constellation Energy delivering power tied to an Illinois plant upgrade. That's a retailer, not a hyperscaler, buying nuclear. The customer base for clean firm power just got a lot wider.
But zoom out and the pattern is stranger than any single deal. The AI electricity boom is producing two parallel grids: one public, interconnected, and subject to regulatory scrutiny; one private, off-grid, and approved in some states in as little as 45 days. Reuters identified more than a dozen off-grid power projects serving data centers that won approval in under a year, with Ohio law allowing certain plants to clear permitting without public hearings at all. Meta's Bowling Green data center in Wood County has a natural gas plant going up across the street from a residential neighborhood — neighbors say they weren't told it was coming.
The Nuclear Track Is Moving Faster and Cleaner
Meanwhile, the advanced reactor pipeline is hitting real milestones. Valar Atomics' Ward 250 reactor achieved criticality on June 18 — a self-sustaining chain reaction — under the DOE's Reactor Pilot Program, which provides a streamlined authorization pathway designed for next-generation designs rather than the legacy light-water framework. That's the program's second breakthrough. X-energy, backed by Amazon, cleared its NRC environmental assessment for a four-reactor Xe-100 project near Corpus Christi, with each reactor designed for 80 MW of electric output. Amazon has said it will support up to 5 GW of new nuclear capacity through power agreements tied to its data center growth.
The IEA reported that data center electricity demand rose 17% in 2025, against 3% growth in global electricity demand overall. That gap is the civilizational signal. The demand is real, the capital is moving, and the reactor designs are proving out.
The question worth watching: which track scales faster? Off-grid gas plants can get permitted in weeks, but they lock in fuel price exposure and community opposition. Nuclear PPAs take years to negotiate and longer to build — but Walmart buying one signals that the market for firm, clean electrons is broadening beyond the hyperscalers who started this race. Watch for whether FERC moves to assert jurisdiction over the off-grid gas buildout, and whether the DOE pilot program produces a third criticality milestone before year-end. Those two data points will tell you which track is actually winning.