#30 of 30 · AI lab
xAI (Grok)
81 gas turbines across two sites, most of them beyond their permits.
In plain words
How scores workxAI scores 19 out of 100 — laggard. Little or no disclosure, fossil-backed capacity, or active disputes with regulators and communities. Confidence in this score is mostly estimates (C).
What helps
- Nothing on record.
What hurts
- Efficiency · Closed frontier models with no disclosures of any kind.
- Carbon · Colossus has used methane gas turbines for primary power since opening; 35 turbines were on site in 2025 versus 15 permitted.
- Carbon · Colossus 2 added 19 turbines in spring 2026 for a total of 46 gas units — above the 41 permitted — supplying more than 500 MW.
What nobody knows
- Per-prompt energy disclosed
- Per-prompt water disclosed
- Training emissions in model cards
- Annual environmental report
- Location-based Scope 2 reported
- +4 more
xAI's Colossus supercomputer in Memphis has run on methane gas turbines since it opened. Aerial imagery counted 35 turbines on site against a permit for 15; the Southern Environmental Law Center estimates more than 2,000 tons of NOx a year. At Colossus 2 in Southaven, Mississippi, records show 46 gas units by May 2026 against a permit for 41, and the $80 million water-recycling plant xAI promised Memphis was paused in April 2026. The company has disclosed no energy, water or emissions data.
Key figures
Per-prompt and fleet metrics. Hover a title for what it means; open “How we got this number” for the working.
ecogpt.co estimate; no company figure.
How we got this number
Grok's frontier models are closed and unmeasured; comparable in class to GPT-4o, which Epoch puts at about 0.3 Wh per typical query. Uncertainty roughly ±3×.
On-site cooling only, so comparable with Google and OpenAI's figures.
How we got this number
0.3 Wh per prompt × 0.6 L/kWh (estimated WUE from Colossus 1's reported water draw). Counting the water evaporated to generate the electricity adds ≈0.54 mL.
Location-based: what the grid actually emitted. Renewable certificates would bring the market-based figure near zero.
How we got this number
0.3 Wh × 500 gCO₂/kWh (on-site gas turbines, location-based). Most of Colossus runs on simple-cycle gas turbines at roughly 500 gCO₂/kWh.
Location-based estimate for the AI fleet only; not comparable with a full corporate inventory.
How we got this number
800 MW × 8,760 h × 80% utilisation × 500 gCO₂/kWh (on-site gas turbines). Compute only — nothing else the company does is counted.
How we got this number
Colossus 2's turbines alone exceed Colossus 1's entire draw; compute and on-site combustion more than double between 2025 and 2026.
How we got this number
Colossus 1 uses more than one million gallons a day (3,800 m³) against roughly 7,200 MWh of daily electricity, i.e. ≥0.5 L/kWh of evaporative cooling.
How we got this number
TVA's grid is roughly 60% nuclear and hydro, but more than half of Colossus's load is met by on-site gas turbines; the blend is about 30% carbon-free.
Hardware & materials
The chips, power, copper and future e-waste behind the fleet — the part sustainability reports leave out
GPUs, TPUs or custom accelerators the company runs. Analyst figures are in H100-equivalents, company figures in physical chips.
How we got this number
≈200,000 H100/H200 plus 30,000 GB200 at Colossus 1 (SemiAnalysis); at least 110,000 GB200 at Colossus 2, heading for 550,000.
Megawatts the AI fleet pulls. One megawatt runs roughly 750 US homes.
How we got this number
Colossus 1 draws about 300 MW (SemiAnalysis); the 46 gas units installed at Colossus 2 by May 2026 add more than 500 MW of on-site generation, with 2 GW the stated goal.
Terawatt-hours per year. One TWh is a year of electricity for about 95,000 US homes.
How we got this number
800 MW × 8,760 h × 80% utilisation. Compute fleet only.
CO₂e emitted making the chips and servers before they answer a single prompt.
How we got this number
340,000 accelerators × 514 kg CO₂e each (chip plus share of the host server). Emitted in manufacturing, before the first prompt is served.
Tonnes of server hardware that will be retired in three to five years.
How we got this number
340,000 accelerators × 17 kg of server hardware each. Tomorrow's e-waste unless reused; generative AI could produce 2.5 Mt of it a year by 2030.
Tonnes of copper in cabling, busbars and transformers.
How we got this number
800 MW × 27 t of copper per MW (cabling, busbars, transformers).
Diesel backup units or gas turbines at the data centres, permitted or observed.
How we got this number
Permits covered 15 and 41 respectively.
Share of retired servers and parts given a second life.
Kilograms of antimony-equivalent, the life-cycle unit for scarce minerals consumed.
Score breakdown
Each pillar is 0–100; weights are fixed across the index
- Closed frontier models with no disclosures of any kind. Inside Climate News
- Colossus has used methane gas turbines for primary power since opening; 35 turbines were on site in 2025 versus 15 permitted. Inside Climate NewsData Center Dynamics
- Colossus 2 added 19 turbines in spring 2026 for a total of 46 gas units — above the 41 permitted — supplying more than 500 MW. Data Center Dynamics
- Colossus 1 needs more than a million gallons of water a day; xAI broke ground on an $80M greywater plant to spare the Memphis Sand aquifer, then paused it indefinitely in April 2026. Restart is now promised for 2027. Data Center DynamicsFOX13 Memphis
- No environmental report, permits contested, no model-level data. Tennessee Lookout
- No climate, energy or water targets published. Inside Climate News
- SELC, Earthjustice and the NAACP sent a notice of intent to sue under the Clean Air Act; NAACP and Young, Gifted and Green appealed the 15-turbine permit. Data Center DynamicsTennessee Lookout
- Turbine installations at Colossus 2 exceeded the permitted count within two months of approval. Data Center Dynamics
- xAI calls the allegations 'baseless and politically driven'. Data Center Dynamics
Models
What this company ships, and what each prompt costs
| Model | Weights | Energy / prompt | Water | Training CO₂e |
|---|---|---|---|---|
| Grok 3 / 4 Frontier (undisclosed) | Closed | 0.30 Wh Estimateecogpt.co estimate. Our own estimate from published factors. The working is shown next to the number; treat it as an order of magnitude, not a measurement. | 0.180 mL Estimateecogpt.co estimate. Our own estimate from published factors. The working is shown next to the number; treat it as an order of magnitude, not a measurement. | 150,000 t Estimateecogpt.co estimate. Our own estimate from published factors. The working is shown next to the number; treat it as an order of magnitude, not a measurement. |
Where the compute lives
Named sites from company disclosures and press reporting
- ColossusMemphis, Tennessee, USA · 35 gas turbines counted vs 15 permitted; ≈300 MW.
- Colossus 2Southaven, Mississippi, USA · 46 gas units vs 41 permitted; >500 MW.
Timeline
Incidents and developments involving this company
xAI installs 19 more gas turbines at Colossus 2, taking the Southaven site to 46 units
Records obtained by the Southern Environmental Law Center show xAI added 19 portable gas turbines to its Colossus 2 campus in Southaven, Mississippi between late March and early May 2026 — 46 units in total against a permit for 41, with more than 500 MW of capacity.
xAIxAI pauses the $80M Memphis water-recycling plant it promised; restart pledged for 2027
Colossus 1 needs more than a million gallons of water a day. The greywater plant xAI broke ground on to spare the Memphis Sand aquifer went on 'indefinite pause' in April 2026; after pressure from the mayor the company committed to resume no later than the first quarter of 2027.
xAIxAI runs 35 gas turbines at Colossus against a permit for 15
Aerial imagery counted 35 methane gas turbines at xAI's Memphis supercomputer — more than double the 15 the Shelby County Health Department permitted. SELC estimates over 2,000 tons of NOx a year.
xAI