The bottom-up part of the framework produced the FOAK costs for the four technology archetypes. Then, the capital costs were built up from the installed equipment costs and are in 2019 USD. The KOH BPMED and MgO ambient weathering installed equipment costs were scaled down as the details in literature were for plants larger than the here assumed FOAK scale. The scaling methodology is identical to that used in the ESI Figures S6-S9 and is detailed in the captions of these figures. The installed equipment costs are available in the ESI Table . Email: jpy1@hw.ac.uk RCCS, Heriot-Watt University