Filtration is good enough that it could technically capture everything.
Technically you could plant enough trees to capture all the CO2 as well.
The energy required to make all the filters and plant and maintain all the trees might be greater than the energy produced by coal though, and that is the issue.
The whole "plant trees" thing doesn't work too well because you'll run out of space long before you run out of hydrocarbons to dig up and burn. Plus, the trees need to stay standing; if at any point they're cut and burnt, or die and decay, then all the CO2 is released again. CO2 buried underground in the form of coal or oil is a much better long-term storage solution for CO2 than trees up on the surface. The logical thing to do would be to start burying CO2, not continue digging it up and releasing it.
No they don't. They need to be harvested and used for timber products, where the carbon can stay locked in for decades or longer. The land can then be replanted for more carbon removal.
Ideally you would use trees to make engineered wood products that replace steel and concrete, the production of which also release large amounts of CO2.
That assumes that young trees and forests have the same carbon capturing efficiencies, when I believe it’s older trees and forests that have significantly greater carbon absorbing capabilities.
I'm unfamiliar with the quality of this publication, but it reports on a study suggesting younger forests are better at carbon dioxide sequestration than older forests:
'Tropical rainforests, the revered "lungs of the planet," were once thought to take the cake when it comes to carbon sequestration. But a new study adds to a growing body of evidence that other types of forest may actually be better at sucking CO2 out of the atmosphere. Specifically it finds that young temperate forests may be more effective carbon sinks than are old rainforests.'
It is pretty silly, because why would you go to greater lengths to dig up coal when you have all this biochar you've just created at the surface that you could more easily burn to release more energy?
Filtration is good enough that it could technically capture everything.
Technically you could plant enough trees to capture all the CO2 as well.
The energy required to make all the filters and plant and maintain all the trees might be greater than the energy produced by coal though, and that is the issue.