Indeed I work for a large, public utility, and we are also selling power onto the grid--profitably--from a large, utility scale batter that we operate in Texas.
For maximum of about 6 hours, but usually less, right? Those batteries reduce peak load, which is critical, but it's not really the answer to getting off of renewables. There isn't enough lithium in the world to use batteries as long term grid storage (10days of insufficient generation by renewables).
Aren’t transmission lines still going to be available to move renewable energy generation from areas where the sun is shining or wind is blowing to areas where they are not? I assume you don’t predict the wind and sun won’t cooperate for days on end over an entire region? I suspect renewable generation can be over built to provide a buffer as well. It’s not like we’ll be wasting fuel if we over build the wind farms or solar farms. I suspect that between battery backup and using transmission lines to move production around regionally, we can eventually get away from fossils fuel generation completely. Eventually everyone will also have their own emergency backup power parked in their garage (EV battery). The average EV car battery can provide multiple days of backup if used conservatively. Any one paying attention to all the extreme weather, drought, fires, etc. realizes whatever the challenges of this energy transition the current system is a road to ruin if we don’t hit the off ramp NOW.
Nope, that's not how the grid works.
> I suspect renewable generation can be over built to provide a buffer as well
Technically, it could... but it's only at 11% of total production right now. And that production is largely the easiest to produce (in optimal areas AND at optimal times). As renewables increase in ubiquity, we will be able to use less of them. If a solar farm is producing sun right now, 100% of it goes into the grid. If we "overbuild" it, soon there will a graduating scale of efficiency losses (transmission, batteries, etc).
Basically, it's not possible to use renewables to meet our emissions goals. We need other non-polluting methods. Namely, Nuclear.
Transmission lines get congested. Batteries degrade. Residential backup for non-critical systems for a couple of days is no where NEAR the grid stability we need on a commercial and industrial scale.
I don't have time to write all of this out... but it's more than just using transmission lines. We need to build multi billion dollar DC converters for high voltage DC transmission. The grid is incredibly complicated and not built with renewables in mind (although they are working to fix that)
There literally isn't enough lithium on the planet to provide nationwide battery storage. IF we do this on renewables+batteries alone, we will need to use something cheap like flow batteries. A large scale battery that reduces peak load for 6 hours is about the same cost as a peak gas plant. One that provides for 12 hours is twice as expensive as that same peak gas plant. And so on... a peaker gas plant that can handle production outages for 5 days is 20X cheaper than the battery equivalent. Batteries just don't scale well (especially expensive lithium ones). We need pumped hydro or thermal storage or something that reduces cost with scale.
Battery backup providing 15kWh to a house is nothing. What do you do for a food production facility that needs 150,000kWh to run? Install 5000 power walls? What if that facility needs 2 days of full power (not "conservative usage") Now you install 10,000 power walls? A facility isn't going to spent 75million on batteries that can only last two days. Either personally or on the grid.
I say all of this because I think we are chasing the wrong pot of gold here. I want the grid to be carbon free... and we're using the treasures of low hanging "renewable" fruit too much it will get harder and harder to use as it scales on the grid (contrary to many things in the market).