This one goes into pretty good detail about the challenges in CA in particular:

https://energy.mit.edu/news/decarbonizing-the-u-s-power-grid/

But at 50 grams of CO2 per kWh, the ban on nuclear makes a significant difference. “Without nuclear, there’s about a 45% increase in total system size, which is really quite substantial,” says Farnsworth. “It’s a vastly different system, and it’s more expensive.” Indeed, the cost of electricity would increase by 7%.

Going one step further, the researchers performed an analysis to determine the most decarbonized system possible in California. Without nuclear, the state could reach 40 grams of CO2 per kWh. “But when you allow for nuclear, you can get all the way down to 16 grams of CO2 per kWh,” says Farnsworth. “We found that California needs nuclear more than any other region due to its poor wind resources.”

TL;DR you can do it with batteries it just costs more, and getting consumers to accept higher electricity prices in order to protect the environment is already going to be a tough sell politically. Of course, so is nuclear, so I do support continued efforts into some more novel sources of baseline power such as floating offshore wind and advanced geothermal. However, these are not ready to be implemented at scale today and the federal government is currently making offshore wind nearly impossible to construct. So I don't know. There aren't any easy answers, unfortunately, but we have to hope either the political or technological landscape changes somehow to make deep decarbonization possible.