CO2 that has been converted to biomass represents a potential reservoir of chemical feed stock. The well-developed industry of chemical intermediates that has arisen in the 20th century from petroleum (and to a lesser extent, coal), can potentially turn to utilization of wood - as was practiced in the early part of the 20th century.
After CO2 is captured, it can be processed into useful materials. These processing steps are source-agnostic, meaning they tend to be independent of the means for recovering the CO2 - they are potentially applicable to multiple CDR methods including DAC, BECCS (or other CCS processes), biochar and by extension, other biomass-producing approaches. If the process of capture has produced carbonate mineral, then that can be incorporated into some matrix like concrete. If the CO2 is in gas form, it can be mineralized in a manufacturing process that forms carbonates as part of the finished product. {identify specific processes}
Aside - some chemistry: Carbon dioxide contains oxidized carbon - meaning the carbon has a “formal charge” or oxidation state of +4 because its four valence electrons are more strongly held by the bonded oxygen atoms. To restore the electrons to the control of the carbon atoms in some degree will reduce their oxidation state; the oxidation state of elements is zero. For every oxidation, there is a corresponding reduction, so reactions that change oxidation states of atoms are called oxidation-reduction reactions, or “redox reactions”.
CO2 + C = 2CO
In this reaction, which tends to require high temperature, carbon dioxide is converted to carbon monoxide and the oxidation state of the carbon in CO2 is reduced from +4 to +2. Carbon monoxide is much more chemically reactive than carbon dioxide, so a variety of useful chemicals can be produced from it.
CO2 = C + O2
In this reaction, carbon dioxide is completely decomposed to elements. The reaction requires addition of at least the same amount of energy as would be released from combustion of an equal amount of carbon (i.e. it reverses the reaction). However there can be economically beneficial reasons for this reaction: the form of carbon created by this process may be more desirable, and the carbon sequestered by this process has high permanence because it cannot easily re-oxidize.
Projects
UP Catalyst - molten salt electrolytic reduction of CO2 for graphite production