TerraWatt Alton (former Alton Steel)
A developer campus by TerraWatt in Alton (Madison County), IL, on the MISO grid. Status: proposed.
Grid and gas impact
At full buildout this campus is announced at 200 MW. After phasing to 2030 and weighting by build stage, the index expects about 30 MW running by 2030.
At that level it would use about 197 GWh of electricity a year, roughly what 18,000 US homes use (EIA average of about 10,800 kWh per home), and add about 2.3 MMcf/d of natural gas burn on an average day, counting both on-site generation and the region's gas-fired power plants.
Its rating is driven by grid load: power is expected to come mostly from the utility grid, so the effect shows up in transmission, capacity and generation needs, and in the gas burned by the region's power plants. Rated 1 of 4 bolts. Outlined bolts mean the campus is approved, announced or proposed and may not be built as planned.
Latest update. New Nov 3, 2026: contingent purchase of the 381-acre steel site; rezoning and an Ameren Illinois study pending.
Fact sheet
- Index ID
- DC-086
- Campus
- TerraWatt Alton (former Alton Steel)
- Developer / tenant
- TerraWatt
- Segment
- Developer campus
- Location
- Alton (Madison County), IL
- State / province
- Illinois
- Country
- United States
- Metro
- St. Louis
- Grid region
- MISO
- Electric utility
- Ameren Illinois
- Status
- Proposed (counts 15% toward 2030)
- Online / target
- Not disclosed
- Announced capacity
- 200 MW (Reported (unspecified))
- Expected load by 2030
- 30 MW (index estimate)
- Annual energy at expected load
- about 197 GWh
- Power supply
- Not disclosed
- Added gas burn, average day
- 2.3 MMcf/d (index estimate)
- Impact rating
- (1 of 4; scale)
- Confidence
- C (One secondary source)
- Last reviewed
- November 3, 2026
Sources
- TerraWatt data center proposal for the former Alton Steel siteSt. Louis Public Radio · Oct 21, 2026
- Gigawatt-scale data center proposed for steel mill in IllinoisData Center Dynamics · 2026Not retrieved; resolved via St. Louis Public Radio (200 MW)
Every source used across the index is listed in the source log. Spotted an error? Email [email protected] with "Correction: DC-086" in the subject.
How to cite
Data Center Index (datacenterindex.info), Discovery Energy. "TerraWatt Alton (former Alton Steel)" (DC-086), https://datacenterindex.info/campuses/dc-086-terrawatt-alton-former-alton-steel/, updated November 3, 2026.