Colossus 1 & 2 — xAI's Memphis Gigawatt Campus

1 · The speed record

When xAI acquired the former Electrolux manufacturing plant in South Memphis in early 2024, no one believed the timeline. Elon Musk promised a working 100,000-H100 cluster by late summer. That's roughly the largest single-site GPU installation ever built, and it would normally take 18–36 months.

Colossus came online on schedule: 122 days from construction start to first training run(July 2024). Within three months of the original milestone, xAI doubled capacity to 200,000 GPUs — a mix of H100s and H200s. By early 2026 the company was publicly targeting 1 million GPUs across the combined Memphis + Southaven footprint.

2 · Power — the controversial part

A 250 MW AI campus in 2024 exceeded every available slot in the Memphis Light, Gas & Water (MLGW) interconnection queue. xAI's answer: build its own substation, and in the meantime, run gas turbines.

The substation

xAI paid $35M to finance a 150 MW MLGW substation — the first time in modern memory a tech company directly financed utility-grade infrastructure. The build took 97 days versus the typical 2.5 years. A second substation is now being built at an additional $20M cost.

The turbines

To bridge the gap, xAI installed 35 gas turbines generating 420 MW on the Colossus 1 site. The regulatory trick: Shelby County only requires air permits for generators in place more than 364 days. xAI initially ran them as "portable" — unpermitted.

The Southern Environmental Law Center, representing the Memphis NAACP, filed Clean Air Act notices. xAI removed the unpermitted turbines and obtained permits for the remaining 15. In January 2026, the EPA revised its New Source Performance Standard: large methane turbines now require permits even for temporary operations.

For Colossus 2 in Southaven, Mississippi, xAI installed 27 turbines generating up to 495 MW — equivalent to a small conventional power plant. Total announced air emissions: between 1,200–2,000 tons of NOx per year from Colossus 1 alone, likely making it the largest industrial NOx emitter in Memphis.

The long-term plan

Turbine permits expire in 2027. By then xAI expects to rely on two MLGW substations, a 500-acre solar farmunder planning near the site, and 168 Tesla Megapack units (150 MW total) for grid-decoupling battery storage.

Source: Shelby County Health Department permit filings · SELC / NAACP Clean Air Act notices of intent · MLGW press materials · SemiAnalysis "Colossus 2: First Gigawatt Datacenter" (Dylan Patel, Jan 2026) · Solaris Energy Infrastructure investor disclosures (NYSE: SEI).

3 · Silicon — the rental-fleet trick

Public fact: Colossus began with 100,000 H100 SXM5s in custom liquid-cooled Supermicro chassis. Expansion phases added H200 and (reportedly) GB200 NVL72 racks.

A less-publicized fact worth understanding: NYSE-listed Solaris Energy Infrastructure owns a 600 MW rental fleet of gas turbines, roughly 400 MW of which currently serves xAI. Of Solaris's 1,700 MW order book, 67% is committed to xAI — ~1,140 MW total, with 240 MW at Colossus 1 and 900 MW going into a 50.1/49.9 Solaris-xAI JV. By Q2 2027, Solaris expects over 1.1 GW of operating turbines serving xAI.

This is novel infrastructure finance: xAI gets gigawatt-scale firm power without waiting for utility interconnect, and Solaris gets long-term baseload contracts on owned assets. It's effectively bring-your-own-power as a service — a model that didn't exist 18 months ago.

4 · Cooling — direct liquid, from day one

Colossus 1 was built with direct liquid cooling (DLC) on the H100 cold plates from the start. The facility loop returns to a central mechanical yard with dry coolers, reflecting Memphis's hot-humid climate (~2,200 free-cooling hours/year). PUE disclosures are not public but analyst estimates put it around 1.20–1.25, typical for DLC deployments in that climate.

5 · Lessons from Colossus

• Speed is an engineering discipline. Parallel permitting, parallel substation + building construction, custom chassis design ordered before the first GPU shipment. xAI did not invent new physics — they removed every sequential dependency.
• Self-generated power is the new escape hatch. When the grid queue is 5+ years, on-site turbines win over compliance. The environmental and political cost is real and pending.
• Environmental approval is a cost, not a blocker. The NAACP + SELC campaign forced turbine removal and an EPA rule change, but Colossus still ran for 18+ months unpermitted. The playbook seems to be: build now, litigate later.
• Rental turbines + batteries is the bridge. Until substations and solar come online, xAI is paying Solaris to rent firm power. Worth studying as a financial model for other latecomers to the grid queue.