The period occured in 2024 between late winter and early summer. “Compared to the same period in 2023, solar output in California is up 31%, wind power is up 8%, and batteries are up a staggering 105%.”
Link to the study PDF mentioned in the article: https://web.stanford.edu/group/efmh/jacobson/Articles/Others/25-CaliforniaWWS.pdf
One of the paper’s cowriters is Mark Z. Jacobson, professor of civil and environmental engineering and director of the atmosphere/energy program at Stanford University.
Title is incorrect. Of these 98 days, the grid was 100% renewable-powered for only 4.84 hours per day on average (10.1 hours per day maximum). The title implies that it was renewable-powered for 24 hours per day.
The actual title of the linked pdf is:
This article seems to be a response to accusations that variable power output of solar/wind causes blackouts. In this study, there were zero blackouts caused by 100% renewable power supply. Also, the study period was an arbitrary set of 116 days. The 98 days were not a continuous period, nor were they 98 days of a 365 day period.
(At time of this comment, the title of this post is “The California grid ran on 100% renewables with no blackouts or cost rises for a record 98 days”.)
Jacobson is a fantasist who has been publishing misleading work for years claiming there are no issues with 100% renewables right now (or indead there were no issues 10 years ago).