00:00Power grids on five continents pulse every 60 seconds, and scientists think they know why.
00:05The tiny change in frequency has been documented since at least 2014.
00:10It appears in grids in continental Europe, Britain, Australia, and the United States.
00:15Researchers at the University of Cologne traced it to uninterruptible power supplies.
00:20These backup systems are used in hospitals and data centers.
00:23Every minute, some perform routine battery checks that create small surges in demand.
00:28In measurements at a research campus in Germany, the pattern appeared in four buildings with those systems and none without.
00:35Digital clocks can sync. So many devices act at once.
00:39The fluctuations are small, only a few millihertz, and pose no immediate threat.
00:44But the researchers warn the problem could grow as data centers and batteries spread.
00:48One manufacturer has already issued a software update.
00:52The study appeared in Nature Energy.
00:55This video contains stock footage and content created or enhanced using AI-assisted tools.
