I would strongly suggest investigating the claims of http://www.innovationconcepts.eu/res/literatuurSchuiling/oli... that after mining, milling, and then being spread in the ocean, olivine rocks weather quickly and take out CO2. The estimated costs of large scale CO2 sequestration this way are surprisingly reasonable, and the technology is already available.
Also the various ocean technologies are going to run into the same environmental complaints as the idea of seeding otherwise barren areas of the ocean with missing metals, causing algae blooms that sink to the bottom. See https://www.scientificamerican.com/article/iron-dumping-ocea... for a discussion of some of those. (And see https://www.forbes.com/sites/timworstall/2014/04/28/iron-fer... for a more laudatory article about this in the general press.) If you can deal with the regulatory concerns, the existing low-tech solution is one of the cheaper ways of removing CO2 that is known.
Speaking personally, I understand the qualms of environmentalists but consider the possibility of local toxic algae blooms to be a less serious environmental disaster than the otherwise certain ocean acidification that will wipe out all shellfish species worldwide. Yeah, nobody wants to accept a bad outcome, but in this case I think it is better than the alternative.
Also the various ocean technologies are going to run into the same environmental complaints as the idea of seeding otherwise barren areas of the ocean with missing metals, causing algae blooms that sink to the bottom. See https://www.scientificamerican.com/article/iron-dumping-ocea... for a discussion of some of those. (And see https://www.forbes.com/sites/timworstall/2014/04/28/iron-fer... for a more laudatory article about this in the general press.) If you can deal with the regulatory concerns, the existing low-tech solution is one of the cheaper ways of removing CO2 that is known.
Speaking personally, I understand the qualms of environmentalists but consider the possibility of local toxic algae blooms to be a less serious environmental disaster than the otherwise certain ocean acidification that will wipe out all shellfish species worldwide. Yeah, nobody wants to accept a bad outcome, but in this case I think it is better than the alternative.