Mystery of 60-Second Fluctuations in Power Grids Solved

For years, Germany’s transmission system operator recorded a small, unusually regular dip in European grid frequency every 60 seconds. A research team led by Dirk Witthaut at Forschungszentrum Jülich traced the pattern to large battery-storage systems, whose built-in power checks often begin at the start of each minute. Each check briefly increases electricity consumption; when many devices act together, their synchronized demand produces a measurable grid disturbance. Researchers first suspected a clock-driven cause, then found matching minute-by-minute consumption patterns at sites with backup batteries while monitoring equipment at 80 locations on Jülich’s Living Lab Energy Campus. The effect is not confined to Europe: evidence points to a global phenomenon.

Although the fluctuations have not threatened grid security, their regular peaks can make hydroelectric turbines momentarily slow and then speed up again, increasing mechanical wear. The signal’s amplitude in Ireland quadrupled from 2016 to 2021, as data centres with large battery systems grew to account for roughly one-fifth of national electricity demand. The researchers warn that batteries may not be the only devices whose digital controls create synchronized demand; air conditioners, heat pumps and household appliances could also contribute. Because there are no binding standards for the timing of battery checks, manufacturers may have independently settled on the same convenient schedule. A straightforward remedy is to randomize check times so devices no longer draw extra power in unison, helping limit wear as storage capacity expands.