For several years, Tennet Germany—the nation's largest transmission system operator—observed a peculiar phenomenon: the frequency of the European power grid dipped briefly and precisely every 60 seconds. While these fluctuations were not severe enough to threaten grid security, their extreme regularity suggested a systematic cause rather than the random noise typical of electricity trading or the variable feed-in from renewable energy sources. Because the pattern was so consistent, researchers concluded the cause had to be a clock-controlled behavior involving a massive number of devices acting in unison.
A research team led by Dirk Witthaut from Forschungszentrum Jülich investigated the source of these synchronized pulses. By installing measuring points at 80 different locations on the Living Lab Energy Campus, the team identified a specific culprit: large-scale battery storage systems. These systems, which are increasingly deployed worldwide to stabilize the grid, were found to spike in electricity consumption at the start of every minute to perform internal power checks. Because there are currently no binding industry standards for these checks, many manufacturers likely defaulted to a 60-second interval, causing thousands of independent systems to draw power at the exact same moment.
This unintended synchronization has physical consequences for infrastructure, particularly for hydroelectric power stations. The brief spikes in demand cause turbines to slow down momentarily before accelerating back to their original rotational speed, leading to increased mechanical wear and tear. The problem is expected to intensify as battery storage capacity expands; in Ireland, for example, the amplitude of this 1-minute signal quadrupled between 2016 and 2021. The researchers suggest a simple technical fix: manufacturers could distribute these power checks randomly throughout the minute rather than synchronizing them to the clock, thereby smoothing out the demand spikes and preserving equipment longevity.