Reading it, one realizes that the project is primarily a diesel generator installation with a little bit of battery.
Typical gas turbine over 4 hours - ~1000 MWh. This battery bank, 129 MWh.So when wind and batteries are complete, they can store a whopping 25 minutes of wind output. My guess is that this is just enough to fire up some other capacity. Useful, but not a solution to avoiding fossil fuel use.
Is it really about avoiding fossil fuel use?
The voters / utility consumers hear "renewables ... blah blah blah, better reliability, yada yada, Musk will deliver or it's free". Musk press is "worlds biggest battery blah blah blah". It probably is technically useful, but it seems like a win/win as a PR exercise.
It's a point that is often missed. To make solar or wind work well, you need short and long term backups. Making it far more expensive than a simple $/Kwh would imply. Without these backups, "it only works when..." is accurate.