I have fantasies of growing huge, mighty forests, then cutting them down, then dumping the logs into the ocean. (Apparently there are lots of plants that sequester carbon faster than trees, but that’s what I visualize: big barges full of logs are cooler than bundles of sawgrass.)
Screw the Hadean depths, I say! So what if a constant rain of logs disrupts your bougie volcanic vent ecosystems a little. You’re extremophiles, deal with it!
Whenever I’ve shared this with forestry or ocean biology people, they get the same “Oh god, another one of these motherfuckers” look I have when people come to me with dumb ideas about my academic specialty, so I guess there’s probably some reason (or a thousand) we shouldn’t do that. But I’m still going to keep pitching my TED talk on it.
(Not a comment on your idea; just glad to know there are other Monday-morning carbon sequesterers out there.)