KEPCO vanadium flow battery demonstration leaked 2,900 litres of electrolyte

What happened

In July 2025, near the end of a demonstration project, a vanadium redox flow battery (VRFB) energy storage system operated by Korea Electric Power Corporation (KEPCO) leaked electrolyte at a demonstration site in Naju city. The leak began on 9 July 2025 and lasted about two hours and 30 minutes, releasing roughly 2,900 litres of electrolyte. The electrolyte is an acidic solution of vanadium compounds in sulphuric acid. According to information KEPCO provided to a legislator's office, which was reported in October 2026, the electrolyte flowed through an underground stormwater drain to a retention pond.

Following a request from Naju city, clean-up extended to a nearby stream. A specialist contractor removed 1,760 tonnes of contaminated wastewater and 2,437 tonnes of soil waste. After clean-up, acidity was within the normal range at all six points Naju city asked to be measured.

Contributing factors

KEPCO's research institute identified a prolonged heatwave as the cause. The temperature had been at or above 34 degrees Celsius for 20 consecutive days, and the peak on the day of the leak was 36 degrees Celsius. The heat caused the system connection to repeatedly expand and contract until a pipe fitting came loose. The electrolyte then escaped into the site drainage network.

Lessons learned

1. Check pipe fittings and connections on flow battery systems for thermal cycling fatigue, particularly during prolonged heatwaves.
2. Design secondary containment and drainage isolation so that electrolyte cannot reach stormwater drains or retention ponds.
3. Plan for off-site environmental monitoring and clean-up from the outset, including agreed measurement points with local authorities.

More lessons on weather and external hazards, detection and monitoring, from every incident on the register.

Source

segye.com