That's not long but I guess it's enough

The power plant also became net-positive by producing more electricity than it consumed for about 8.7 seconds. It produced a median of about 2 kilowatts of net power and peaked at 16.5 kilowatts of net power.

“It’s the proof point,” Redd told Ars. “Net-positive is the threshold that matters: the plant made more power than it took to run itself on the seafloor, which no one had done before.”