HENNEPIN
SubstationIllinois · AMEREN ILLINOIS COMPANY
At a glance
HENNEPIN is an electric transmission substation in Illinois, on AMEREN ILLINOIS COMPANY's transmission network. It is classified as sub-transmission (138 kv) and connects 6 transmission lines. Substation proximity is one of the strongest speed-to-power signals for siting a datacenter — interconnection distance to an energized, high-voltage bus is often the binding constraint on time-to-energization.
Voltage & classification
Connected transmission lines
Lines terminating at or passing through this substation, by HIFLD line ID, highest voltage first.
| Line ID | Voltage | Owner | Status | Length |
|---|---|---|---|---|
| #100500 | 138 kV | AMEREN ILLINOIS COMPANY | IN SERVICE | 3.0 mi |
| #120357 | 138 kV | AMEREN ILLINOIS COMPANY | — | 0.1 mi |
| #124651 | 138 kV | AMEREN ILLINOIS COMPANY | IN SERVICE | 0.6 mi |
| #136580 | 138 kV | AMEREN ILLINOIS COMPANY | IN SERVICE | 0.7 mi |
| #146055 | 138 kV | AMEREN ILLINOIS COMPANY | IN SERVICE | 14.4 mi |
| #148680 | 138 kV | AMEREN ILLINOIS COMPANY | IN SERVICE | 1.0 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of HENNEPIN, ranked by DC Readiness. Sites this close to an energized substation carry a strong speed-to-power advantage.
| Site | Type | State | County | Voltage | Capacity | Queue wait | Score |
|---|---|---|---|---|---|---|---|
| Hennepin Power Station | Brownfield | IL | Putnam County | 138 kV | 306 MW | 4.8 yrs | 62.6 |
| EC Coal Marshall County | Greenfield | IL | Marshall County | — | — | 4.8 yrs | 60.1 |
| UNKNOWN123090 | Substation-Adjacent | IL | Marshall County | 138 kV | 100 MW | 4.8 yrs | 59.8 |
| UNKNOWN157084 | Substation-Adjacent | IL | Marshall County | 138 kV | 100 MW | 4.8 yrs | 58.5 |
| OZ Marshall | Greenfield | IL | Marshall | — | — | 4.8 yrs | 58.5 |
| EC Coal Marshall County | Greenfield | IL | Marshall County | — | — | 4.8 yrs | 58.4 |
| EC Coal Putnam County | Greenfield | IL | Putnam County | — | — | 4.8 yrs | 58.2 |
| EC Coal Putnam County | Greenfield | IL | Putnam County | — | — | 4.8 yrs | 58.0 |
How does HENNEPIN compare with other substations in Illinois?
Illinois has 1,986 substation records in HIFLD, of which 209 carry a station name; the rest are unnamed tap points, risers and line ends. 90 named substations in the state are in HENNEPIN's 115–229 kV band (43% of named stations). 95 sit in a higher band. 92 named substations in Illinois operate at 345 kV or above. The highest voltage recorded in the state is 765 kV, and the state median is 161 kV.
Who owns the transmission lines at HENNEPIN?
The 6 connected lines listed above are owned by AMEREN ILLINOIS COMPANY. Line voltages range from 138 kV to 138 kV. Their combined recorded length is about 19.7 miles.
How do candidate sites near HENNEPIN score?
The 8 highest-scoring candidate sites within about 25 miles range from 58 to 63 on the 0–100 DC Readiness scale. They fall in Putnam County, Marshall County, Marshall. The Illinois average across 3,641 scored sites is 54.3. 795 of those Illinois sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is HENNEPIN substation?
HENNEPIN has a maximum voltage of 138 kV. That places it in the 115–229 kV band. The median named US substation in this dataset is 115 kV, so HENNEPIN is above the national midpoint.
How many transmission lines connect to HENNEPIN substation?
6 transmission lines terminate at or pass through HENNEPIN in the HIFLD line data. The connected lines listed here run at 138 kV. Together the listed lines cover about 19.7 miles.
Who owns HENNEPIN substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at HENNEPIN belong to AMEREN ILLINOIS COMPANY. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is HENNEPIN substation located?
HENNEPIN is in Illinois at 41.3019, -89.3149. The datacenter candidate sites closest to it are in Putnam County, Marshall County, Marshall.
Are there datacenter candidate sites near HENNEPIN substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of HENNEPIN. The highest-scoring is Hennepin Power Station at 63/100. Across Illinois, the average DC Readiness score is 54.3.
Other 138 kV substations in Illinois
- EDWARDS· 15 lines
- EAST KEWANEE· 14 lines
- SKOKIE (138 KV)· 12 lines
- FARGO· 9 lines
- HAYFORD· 8 lines
- MUDDY· 8 lines
- NORTH DECATUR· 8 lines
- GRAND TOWER· 7 lines
- All named substations in Illinois· 209 stations
- Datacenter candidate sites in Illinois· 3,641 sites
- Brownfield and retired plant sites in Illinois
- Substations by state
About this data
Source: HIFLD Electric Substations and Transmission Lines (U.S. Department of Homeland Security), as published June 29, 2026. See the methodology for how records are matched, cleaned and scored.
Cite as: GridCensus, “HENNEPIN substation, Illinois”, https://gridcensus.com/substations/illinois/hennepin-306124c2 (data as of June 29, 2026).
Dataset updated . Screening estimates derived from public data sources.
Substation attributes are derived from public HIFLD / EIA infrastructure data and may lag real-world upgrades or retirements. Voltage and connected-line counts are screening figures — confirm available capacity and interconnection terms directly with the operating utility and ISO.
Go deeper than the public screen
Every site and score for HENNEPIN substation, Illinois is free to browse. Pro adds Watchtower on 25 sites, alerts when new candidate sites, datacenters or interconnection-queue requests appear in your markets, score and capacity history, and CSV export. Enterprise adds team seats, weekly data files for all 147,272 sites, the REST API and an MCP server for AI tools.