Arizona Opens Hearings on 1,675 MW Built for Data Center Load

Key Highlights

• Marigold Energy Center, Stanfield, Ariz.: 1,675 MW total — 600 MW solar, 400 MW battery storage, up to 675 MW gas-fired generation.
• Includes a 230kV/500kV substation and about four miles of new 230kV transmission.
• Arizona Power Plant and Transmission Line Siting Committee hearing opens 10 a.m. Monday Sept 21 in Casa Grande and runs weekdays through Sept 25; public comment session Sept 21 at 5:30 p.m.
• Arizona Corporation Commission decision expected November 2026; SRP cites data-center-driven load growth as the driver.

The Signal

• This is the power side of the data center moratorium story, and it is moving faster than the zoning side.
• A utility is asking to build generation for a customer class that counties are actively pausing.
• Gas is 40 percent of the nameplate. That is a firm-capacity decision, not a renewables headline.

Salt River Project's Marigold Energy Center enters its state siting hearing this week: 1,675 MW of new capacity in Pinal County, split between 600 MW of solar, 400 MW of batteries and up to 675 MW of gas turbines, plus a new 230kV/500kV substation and roughly four miles of transmission. The hearing runs Sept 21 through Sept 25, with a commission decision expected in November.

SRP has been explicit that the project responds to load growth from data centers in the Phoenix region. That places Marigold on the opposite side of the same ledger as the 279 active moratoriums the desk reported last week. Counties are slowing approvals for the buildings; the utility is accelerating approvals for the electrons.

The gas share is the tell. Solar and storage serve a daily curve; 675 MW of dispatchable gas serves a customer that runs flat at 2 a.m. in August. A utility does not add that much firm capacity for a speculative queue. It adds it for signed or near-signed load.

For developers, the ACC timeline — decision in November, construction after that — is the real interconnection calendar for the Pinal and southeast Phoenix corridor. Sites without a path to Marigold-era capacity are marketing land, not power.

The hearing's public-comment session is where the political risk shows up. Residents in Stanfield and Casa Grande will argue the generation is being built for out-of-county load, which is the same argument Vance County and Prince William used to justify freezes.

Implications

• Power-side approvals and zoning-side moratoriums are now running on separate clocks in the same metros. The spread between them is the schedule risk in every Arizona data center pro forma.
• Firm gas capacity earmarked for data centers will become a public-utility-commission fight in every Sun Belt state; Marigold is the template for how those fights are argued.
• If Marigold is approved in November, Pinal County land with existing transmission adjacency reprices before a single data center is entitled.

Counties are pausing the buildings while utilities are building the power; the gap between those two calendars is now the biggest schedule risk in Sun Belt data centers.