Large battery energy storage systems (BESS) are not really generation systems, but they can strongly optimize many generation systems including intermittent renewables like photovoltaic (PV) and wind turbines. It is also not transmission, but can also optimize, and in some cases defer transmission upgrades.
I recently came across the following article regarding my home state (California).
“The California Public Utilities Commission is pushing forward two proposed battery energy storage facilities in Central California instead of upgrading existing nearby transmission lines, citing a lower cost for the battery storage projects...”
I researched the title issue and came across a really good DOE document on this issue, and the main subject of this post is a summary of that document.