One Steel Mill Controls How Fast America's Power Grid Can Grow
Every large power transformer needs a magnetic steel that barely wastes energy as heat. Almost none of it is made in the US anymore — except at two aging plants in Pennsylvania and Ohio, run by one company. AI's power hunger just ran straight into that bottleneck.
The race to power-on
Two builds share one clock: a data center's construction, and the large power transformer it needs before it can draw a watt. Toggle the era to see the wait shift, then scrub or press Play. Simplified model — construction ≈24 months (typical shell-and-core range); transformer lead time ≈15 months pre-2020 vs. ≈54 months in 2026 for a custom Tier-1 unit (reported range 48-60 months) — illustrative, not one specific project's real schedule.
Pick an era, then scrub or race the clock:
The plain version
Think about the gap between "we found enough power for the data center" and "the data center actually has power." Sitting in that gap is a giant metal box called a power transformer — not a chip, not glamorous, just a hundred-ton object built by winding miles of copper wire around a core made of a very specific magnetic steel. That steel has to be manufactured so it barely wastes energy as heat every time current runs through it 60 times a second.
Here's the surprise: there is essentially one company left making that steel at scale in the US — Cleveland-Cliffs, at two plants in Butler, Pennsylvania and Zanesville, Ohio. Everyone building a large transformer in America — for a data center, a factory, a new solar farm, a hydro dam replacement — is drawing from the same steel, made in the same two towns. Add a specialized copper-winding process on top, and those two materials alone can be roughly half of what a big transformer costs to build.
So when AI data centers, factory electrification, and an aging grid all started ordering transformers at the same time, there was no switch to flip. Federal energy officials found that more than 80% of the large transformers going into the US grid are already imported — and even that overseas supply is now stretched thin. Orders from the biggest manufacturers now take three to five years to arrive, sometimes longer than it takes to build the data center itself. Utilities have learned to order years in advance, occasionally before they know exactly where a project will even go, just to hold a place in line.
The chips get the headlines. A steel mill in Butler, Pennsylvania quietly decides how fast the actual buildout can move.
The expert version
A large power transformer (LPT — generally rated above 100 MVA, the class used at generating stations, bulk substations, and gigawatt-scale campuses) has two dominant, correlated cost drivers: grain-oriented electrical steel (GOES) for the magnetic core, and continuously transposed conductor (CTC) copper for the windings. Per a 2020 US Commerce Department industry survey cited in DOE's July 2024 Large Power Transformer Resilience Report to Congress, GOES and CTC copper each account for roughly 25% of an LPT's final production cost — half the materials bill riding on two specialty inputs. GOES is cold-rolled silicon steel processed so its magnetic domains align along the rolling direction, minimizing hysteresis and eddy-current losses as the core cycles at 60 Hz; producing it at grid scale requires precision annealing and coating lines that few mills anywhere operate.
In the US, that capability sits almost entirely with Cleveland-Cliffs, whose Butler Works (Butler, PA) and Zanesville, OH facilities are the only domestic-scale GOES source, per the company's own disclosures and reporting from Butler Eagle and Utility Dive — a concentration significant enough that the Defense Logistics Agency recently signed a five-year, up-to-$400 million contract with Cliffs to secure GOES supply for military-grade electrical equipment. DOE's report quantifies the downstream effect: over 80% of large power transformers installed in the US are imported, largely from South Korea, Mexico, and other manufacturers, in part because import costs and lead times have historically beaten domestic ones.
That import channel is now saturated too. Wood Mackenzie estimated roughly a 30% supply deficit for power transformers and 10% for distribution transformers in 2025, as AI data-center buildout, industrial electrification, and utility grid-hardening replacement demand converge on the same finite manufacturing slots at GE Vernova, Hitachi Energy, Siemens Energy, and ABB. DOE projects US LPT demand rising from roughly 750 units/year in 2019 toward 900 units/year by 2027. Lead times for a custom, Tier-1 unit have stretched to 3-5 years — reported as high as 48-60 months at Hitachi Energy and 60-plus months (with some order slots quoted into 2031) at GE Vernova — up from roughly 12-18 months before 2020, making transformer procurement, not turbine or switchgear delivery, the longest single item on many interconnection critical paths.