AC transmission: Geopolitics and regulation

Permits, transformer shortages and the 2025 Iberian blackout

The binding constraints are permits, equipment supply and who pays, not technology. Governments are planning further ahead, while the 2025 Iberian blackout showed that voltage control needs attention as grids change.

Tailwinds

FERC Order 1920 requires regional plans looking at least 20 years ahead, redone at least every five years, that consider grid-enhancing technologies; Order 1977 updates federal backstop siting¹¹

ERCOT's 765 kV plan has about 2,468 miles of new lines for about USD 33 billion; Permian Basin demand may reach about 26 GW by 2038⁶⁷

State Grid plans about CNY 4 trillion of grid investment in 2026 to 2030, including 15 new UHV lines¹⁰

MISO selected an Ameren, GridLiance and Dairyland consortium for a 187-mile 765 kV Iowa line, estimated at USD 1.23 billion, due in 2034⁸

Headwinds

The IEA names permitting as the primary cause of transmission project delays²

Wood Mackenzie expects a 30% supply deficit for US power transformers in 2025, with about 80% of supply imported and tariffs adding cost¹³

The IEA tracked about 1,650 GW of advanced-stage solar and wind projects waiting for grid connection²

ENTSO-E's expert panel found the 28 April 2025 Iberian blackout had many interacting causes, including weak voltage and reactive power control and rapid generator disconnections¹⁴

AC grids are national or regional, so the politics is mostly domestic: rights of way across private land, local opposition to towers, and disputes over cost allocation between states or regions. Security of supply cuts both ways: stronger grids reduce blackout risk, but transformers and other long-lead parts have become a strategic bottleneck.

Sources

1. Building the Future Transmission Grid: Executive summary IEA, 2025
2. 2024 Regional Transmission Plan: 345 kV Plan and Texas 765 kV Strategic Transmission Expansion Plan ERCOT, 2025
3. Texas PUC to weigh ERCOT 765-kV transmission plan Utility Dive, 2025
4. MISO selects Ameren, GridLiance and Dairyland consortium for EASL 765 kV project (reporting MISO's cost estimate) American Public Power Association, 2026
5. China plans 15 new ultra-high-voltage transmission lines by 2030 Enerdata, 2026
6. FERC addresses long-term planning, regional transmission cost allocation American Public Power Association, 2024
7. Power transformers and distribution transformers will face supply deficits of 30% and 10% in 2025 Wood Mackenzie, 2025
8. 28 April 2025 Blackout (Iberian incident, factual and final reports) ENTSO-E, 2026