Power Supply Starts at the Site

A factory, data center, or electrified building needs power at its connection point. A state total cannot establish that supply: Texas and ERCOT cover different ground. In the May 2026 capacity snapshot, power plants in Texas add up to 169,833 MW of nameplate; plants inside ERCOT’s footprint add up to 143,958 MW. Neither number says what one parcel can draw.

So take one site everybody has heard of. Epoch AI’s Frontier Data Centers Hub records the OpenAI Stargate campus at 5502 Spinks Rd in Abilene, Texas, at 295 MW. Drop that address on the repo’s grid layers, HIFLD transmission lines and OpenStreetMap substations, and it reads like a site selector’s dream: a 138 kV line 0.6 km from the address point, the 138 kV Abilene Northwest substation 1.4 km away, a 345 kV line 3.3 km away, and the 345 kV Mulberry Creek substation at 3.9 km. (kV is the line’s operating voltage; higher-voltage lines are the ones that move large blocks of power.)

That is everything the map knows, and it is less than it looks. Proximity is the cheapest fact in site selection and the least decisive one. The map draws a 345 kV substation. It does not say whether that substation has 295 MW to spare, where a new request would sit in the utility’s interconnection queue, which upgrades the utility would require, who pays for them, or when they would be energized. It cannot even settle whom you call: OpenStreetMap maps Mulberry Creek twice, about 70 meters apart, once tagged American Electric Power and once tagged Oncor.

The regional numbers make the trap worse, not better. 295 MW is 0.2% of ERCOT’s installed nameplate, a rounding error. In that snapshot gas is ERCOT’s largest installed fuel share at 39.7%, ahead of wind at 25.7% and solar at 15.4%; wind leads in the Southwest Power Pool. These describe generating equipment. Nameplate capacity measures potential output, while generation measures electricity actually produced over time. Neither establishes capacity available to a particular parcel. A region can have plenty of megawatts while the substation down the road has none for you.

The exploration below walks the same site in five steps: the address point, the lines, the substations, the regional number, and the four things no layer records. Distances run from Epoch’s geocoded address point, not from the parcel edge, so read them as approximate.

Use the map for what it is good at: ruling sites out and writing better questions. Compare candidate sites with the same proposed load and operating schedule. For each, obtain the serving utility’s connection capacity, upgrade costs, delivery timetable, and applicable tariff. Those site-specific terms belong in the investment comparison; the distance to a line does not. My rule: a site 4 km from a 345 kV substation, with no written answer from the utility, is not a powered site. It is a site with a view of one.