Energy engineering nerd here - naturally I've heard about it.

Question that Vaclav Smil had raised as a potentially fatal obstacle to large scale carbon capture. All is nice and well when we're trying to sequester 1000 tons of CO2 per year as a pilot project. But once we scale up to ~100Mtons or even ~Gton per year - we'll very quickly run out of places to safely store it. How much is this a real physical constraint vs. Smil's skepticism being cranked up to 11/10?