Better to just not emit it, but nice to have numbers for how big a carbon tax needs to be to encourage reduction over capture.
https://www.resources.org/common-resources/calculating-vario...
The low-hanging fruit is to just stop burning coal for electricity, and to enact that restriction globally.
We can deal with gas, metallurgical coal, oil later. Just get rid of coal now.
I myself like to think of the situation you're describing as the coal costing the utility $15/ton or whatever while the rest of us pay that $100-120/ton to repair the commons.
But certainly different sources will become less viable at different extra costs, and perhaps for coal $15/ton might as well be $100-120/ton.