The recent blackout that swept the Iberian Peninsula and parts of France has brought renewed attention to the risks and rewards of interconnected power grids. While some blamed the scale of European interconnections for the April 28 outage, the broader takeaway is more nuanced: properly managed interconnectors may be critical to resilience.

That message resonates in Japan, where energy experts have long debated the merits of regional interconnection. Japan remains an energy island, with no electrical links to neighboring countries. But with extreme weather events increasing in frequency and the energy transition gaining ground, the idea of linking Japan’s grid to one of its neighbors is again under consideration.

A proposed Japan–Korea subsea power cable would span 220 kilometers across a relatively manageable seabed. Using HVDC (high-voltage direct current) technology, the cable would allow the two countries to trade electricity without directly syncing their grids. That means each grid stays independent, but they can still buy and sell power when desired.

In a scenario similar to the one on the Iberian Peninsula, the Japan–Korea interconnection would provide a critical safety net. A 2 GW HVDC link — the typical scale — could allow one country to support the other with backup electricity during a major grid failure.