[szvsw]

you omitted the immediately following sentence...

>They only need to be cheaper than (IMO inevitable) carbon tax penalties plus the cost of these bricks compared to current methods, which is a rapidly falling curve.

this clearly indicates OP suggests they will become de facto cheaper once the traditionally externalized costs of environmental impact are accounted for.

[s1artibartfast]

The alternatives are also carbon free, which is the point of the parent post.

The comparison is between this and carbon free solar-thermal for energy storage. Saying it doesnt have to be cheaper than solar-thermal simply isnt true.

[szvsw]

Fair fair. Unlike traditional solar thermal though, this can just function as regular node on the electric grid (or even a prosumer) so it is decoupled from the attendant variability. As such they are not quite comparable IMO.