According to NISO, available generation on the National Grid fell sharply from over 4,300MW in the early hours of September 28, 2025, to about 3,200MW at the lowest point. AdvertisementIn a statement released in the early hours of Tuesday, NISO stated that the development heightened pressure on the grid, prompting emergency measures to stabilise supply and avert a nationwide blackout. To mitigate the crisis, the System Operator stated that it ramped up generation from major hydropower stations, injecting over 400MW to cushion the shortfall from gas-fired plants. £In response, the NISO promptly deployed contingency measures to preserve the stability, security, and reliability of the National Grid. “Generation Dispatch and Load Balancing: Real-time load adjustments to match available generation with system demand, while preventing a system frequency collapse.