But keep this in mind: plants evolved lignin to make their structures (trunks, branches, all that) hundreds of millions of years before bacteria and other microorganisms evolved the ability to break down that lignin. So, for hundreds of millions of years, plants captured carbon dioxide by photosynthesis and sequestered it. That's what changed earth's atmosphere from reducing to oxidizing. Fossil carbon is the geological remains of that carbon capture.
It's hard to imagine carbon-capture tech that has the longevity of those planet-wide lignin forests.
But keep this in mind: plants evolved lignin to make their structures (trunks, branches, all that) hundreds of millions of years before bacteria and other microorganisms evolved the ability to break down that lignin. So, for hundreds of millions of years, plants captured carbon dioxide by photosynthesis and sequestered it. That's what changed earth's atmosphere from reducing to oxidizing. Fossil carbon is the geological remains of that carbon capture.
It's hard to imagine carbon-capture tech that has the longevity of those planet-wide lignin forests.