I think the real way to read it is: Renewables are at a point where, combined with battery storage, they can supply 100% if we chose to while being competitive on cost.

The Birmingham case is a perfect example where solar might not be the source, wind is

Yeah

I do think that the batteries side of the equation is handwaved away too much though

Batteries at this scale are going to be awful for the environment once we start to have to decommission and dispose of them

There are no perfect solutions unfortunately

What is the harm, specifically? Is it greater or less than the harm for steel? How?

I have never gotten a clear explanation of this from someone who expresses concern for batteries causing environmental damage. They aren't harmful like car batteries, for example. And the people expressing concern about batteries never seem to express concern for the far greater use of other minerals in their daily life.

Batteries can be recycled though as the degradation is mostly on the kathode anode pair AFAIK

My understanding is they aren't really recycled into the same type or size of battery, so it's still pretty lossy.

Could be wrong though