I have no faith in machines that suck the atmosphere through a straw. The thermodynamics and fluid dynamics just don't pencil out. We need to remove something like 3.5 Tt of CO2, so 3.5 Kt is nothing. Our only hope in this regard is solar/uv-powered systems, mainly biological, for example algaes in pelagic waters (that grow and then die and sink to the bottom of the ocean). These systems aren't trivial to build either.
For other GHG and pollutants there are uv-powered systems like TiO2, olivine etc, though there are also limits to how much they can do.
Basically we have to "mash our hand on the keyboard", i.e. try to do them all, but I can't see machines like these making any meaningful contribution.
Note: I'm working on methane destruction straight in the atmosphere, so I'm putting my money (and my time) where my commenting is.
For other GHG and pollutants there are uv-powered systems like TiO2, olivine etc, though there are also limits to how much they can do.
Basically we have to "mash our hand on the keyboard", i.e. try to do them all, but I can't see machines like these making any meaningful contribution.
Note: I'm working on methane destruction straight in the atmosphere, so I'm putting my money (and my time) where my commenting is.