US Hydropower Faces Supply Chain Challenges With Large Power Transformers

A new report from the National Laboratory of the Rockies looks at a bottleneck in the U.S. power grid: large power transformers, or LPTs. These are the massive devices that step up voltage from hydropower plants so electricity can travel long distances on transmission lines. More than 90% of the power Americans use passes through high-voltage transformers at some point, so this is not just a hydropower issue, it touches the broader grid.

The report found nine challenges slowing down repairs and upgrades to these transformers. The U.S. relies on imports for 80% of the raw materials, like electrical steel and copper, that go into building them. Domestic factories can't keep up with demand, and only a few plants worldwide can build the largest units. Ordering one typically takes 2.5 to 3 years, and up to 5 years for the biggest sizes. Prices have jumped too, rising about 80% in 2025, with a single transformer costing as much as $10 million. Other hurdles include a shrinking pool of skilled workers, the difficulty of hauling these huge, heavy units to remote dam sites, permitting delays, and trade policies that could push material costs even higher.

None of this requires homeowners to do anything. But it's a reminder that grid equipment, not just power plants or transmission lines, can be a slow point in keeping electricity reliable. Slower replacement of aging transformers at hydropower dams could affect how quickly utilities respond to outages or upgrade capacity in some regions over the coming years.