COSMAR
SubstationLouisiana · ENTERGY LOUISIANA LLC
At a glance
COSMAR is an electric transmission substation in Louisiana, on ENTERGY LOUISIANA LLC's transmission network. It is classified as sub-transmission (138 kv) and connects 2 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 |
|---|---|---|---|---|
| #107763 | 138 kV | ENTERGY LOUISIANA LLC | IN SERVICE | 1.5 mi |
| #134184 | 138 kV | ENTERGY LOUISIANA LLC | IN SERVICE | 1.9 mi |
Nearby datacenter candidate sites
Scored candidate sites within roughly 25 miles of COSMAR, 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 |
|---|---|---|---|---|---|---|---|
| WILLOW GLEN (500KV) | Substation-Adjacent | LA | Ascension Parish | 500 kV | 1,000 MW | 4.3 yrs | 71.9 |
| COLY | Substation-Adjacent | LA | Livingston Parish | 500 kV | 1,000 MW | 4.3 yrs | 67.1 |
| UNKNOWN149836 | Substation-Adjacent | LA | Iberville Parish | 500 kV | 1,000 MW | 4.3 yrs | 66.5 |
| OAK VILLA | Substation-Adjacent | LA | East Baton Rouge Parish | 230 kV | 300 MW | 4.3 yrs | 64.7 |
| HAZEL | Substation-Adjacent | LA | East Baton Rouge Parish | 230 kV | 300 MW | 4.3 yrs | 64.7 |
| UNKNOWN112497 | Substation-Adjacent | LA | East Baton Rouge Parish | 230 kV | 300 MW | 4.3 yrs | 64.6 |
| TIGER | Substation-Adjacent | LA | West Baton Rouge Parish | 230 kV | 300 MW | 4.3 yrs | 64.1 |
| UNKNOWN111776 | Substation-Adjacent | LA | East Baton Rouge Parish | 230 kV | 300 MW | 4.3 yrs | 64.1 |
How does COSMAR compare with other substations in Louisiana?
Louisiana has 1,305 substation records in HIFLD, of which 297 carry a station name; the rest are unnamed tap points, risers and line ends. 76 named substations in the state are in COSMAR's 115–229 kV band (26% of named stations). 105 sit in a higher band. 17 named substations in Louisiana operate at 345 kV or above. The highest voltage recorded in the state is 500 kV, and the state median is 138 kV.
Who owns the transmission lines at COSMAR?
The 2 connected lines listed above are owned by ENTERGY LOUISIANA LLC. Line voltages range from 138 kV to 138 kV. Their combined recorded length is about 3.4 miles.
How do candidate sites near COSMAR score?
The 8 highest-scoring candidate sites within about 25 miles range from 64 to 72 on the 0–100 DC Readiness scale. They fall in Ascension Parish, Livingston Parish, Iberville Parish, East Baton Rouge Parish. The Louisiana average across 1,762 scored sites is 53.1. 615 of those Louisiana sites are classed as substation sites (candidate locations generated at an existing substation).
Frequently asked questions
What voltage is COSMAR substation?
COSMAR 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 COSMAR is above the national midpoint.
How many transmission lines connect to COSMAR substation?
2 transmission lines terminate at or pass through COSMAR in the HIFLD line data. The connected lines listed here run at 138 kV. Together the listed lines cover about 3.4 miles.
Who owns COSMAR substation?
HIFLD does not publish substation owners directly. Most of the transmission lines that end at COSMAR belong to ENTERGY LOUISIANA LLC. GridCensus derives this from the line data, so confirm ownership with the utility for anything contractual.
Where is COSMAR substation located?
COSMAR is in Louisiana at 30.2277, -91.0683. The datacenter candidate sites closest to it are in Ascension Parish, Livingston Parish, Iberville Parish.
Are there datacenter candidate sites near COSMAR substation?
GridCensus lists at least 8 scored candidate sites within roughly 25 miles of COSMAR. The highest-scoring is WILLOW GLEN (500KV) at 72/100. Across Louisiana, the average DC Readiness score is 53.1.
Other 138 kV substations in Louisiana
- SCOTT· 11 lines
- MOSSVILLE· 9 lines
- ARSENAL HILL· 8 lines
- SEGURA· 8 lines
- CECILIA· 7 lines
- SOUTH SHREVEPORT· 7 lines
- COCODRIE· 6 lines
- SOLAC· 6 lines
- All named substations in Louisiana· 297 stations
- Datacenter candidate sites in Louisiana· 1,762 sites
- Brownfield and retired plant sites in Louisiana
- 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, “COSMAR substation, Louisiana”, https://gridcensus.com/substations/louisiana/cosmar-4ab8621c (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 COSMAR substation, Louisiana 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.