Current storage solutions: batteries, water in a dam, molten salt.
Energy density: low
Environmental impact: Dams: need to flood a massive area to make a dent. For example the utterly colossal Three Gorges supplies only 1% of China’s power.
Batteries: filled with extremely bad heavy metals. It’s barely OK right now; if we covered the planet in huge battery farms, it would be a catastrophe.
Molten salt/other temperature-based methods: works with turbine-based generators, not solar/wind.
Responsiveness: low, except for batteries.
Ultimately this whole thing needs less shouting and more spreadsheets.
Batteries are not necessarily filled with toxic heavy metals. Consider lithium-iron-phosphate batteries. Iron is not a toxic heavy metal, phosphate is neither toxic nor a metal, and lithium is anything but heavy. Saying batteries categorically have heavy metals is lying. And no, it would not be a catastrophe to build large quantities of batteries.
You don't even mention underground storage of hydrogen, which is by the lowest cost/kWh of storage capacity, much better than batteries for long term energy storage.
Sorry about the emotion, but I get annoyed at the cavalcade of nonsense you people spew on this issue.
The sibling comment has already showed all the ways in which you are wrong. So I'll address only this part. " I also see no reason to believe that is true". That's the problem with starry-eyed proponents of anything really: they chose belief over facts.
"All energy storage solutions we have are low capacity, slow to charge, slow to bring online, and often are extremely harmful to the environment to produce."
This is 100% bullshit. Energy storage solutions can be scaled as high as we want. They can charge as fast as is needed. By "slow to bring online" you might mean two things (cannot be switch on to deliver power to the grid from an off state quickly, or cannot be built quickly), both of which are false. As for "extremely harmful to the environment", I also see no reason to believe that is true, especially compared to either the harm of CO2 or the harm imposed by the existence of industrial civilzation at all.
So, you listed reasons, and they appear spurious. Care to defend your claims?