While the fact that the bacteria can convert CO2 to carbonate faster than by other means is interesting, this can solve only half of the problem of CO2 sequeste

While the fact that the bacteria can convert CO2 to carbonate faster than by other means is interesting, this can solve only half of the problem of CO2 sequestering. The carbonate ions must combine with metal ions, like calcium and magnesium, so a source of those ions is needed, where the ions are not already combined into salts, i.e. either calcium oxide or magnesium oxide is needed. Currently, the cheapest way to obtain such metal oxides is by decomposing their carbonates, releasing CO2 into the atmosphere. So sequestering CO2 into carbonates does not appear to be feasible at large scale, for lack of a source of uncombined oxides. The only big enough source of oxides would be the decomposition of silicates, but that requires a tremendous amount of energy. So for this direction, the research would need to concentrate on efficient methods for decomposing silicates, and only if that is solved on how to convert faster CO2 into carbonate ions. An example of a method for decomposing silicates would be the electrolysis of salt to make caustic soda that can easily sequester CO2 into baking soda, then the hydrogen chloride byproduct could be reacted at extremely high pressures with alkaline feldspar, regenerating the salt, allowing the start of another cycle. However it would not be easy to scale such a process to big quantities, because the only material that can contain HCl at the pressures needed to react with silicates is Teflon, so it would not be easy to make reaction vessels big enough. Otherwise, the only practical solution for sequestering CO2 is its conversion into organic products, preferably into hydrocarbons. Hydrocarbons with high molecular weight, like polyethylene, could store safely carbon forever. In this direction, the most promising is the research for reducing CO2 by electrolysis (into carbon monoxide, which can be reacted with dihydrogen also obtained by electrolysis to combine into organic substances).