The coloured matrices in Figure show how the median costs, using our middle or most likely values for all parameters, vary across locations and electricity sources. Generally, higher savings from rational siting and electricity source selection are observed at the FOAK scale. The MgO ambient weathering process is the most location and electricity source agnostic economically, so technical performance and availability of MgCO3 may be crucial to siting this technology. China is the cheapest location for the FOAK cost in Figure . The lower costs are primarily due to the decreased capital costs, as a result of the low cost of labour, which has a knock-on effect on the cost of raw materials. Location seems to be a more critical factor to cost than electricity source when considering a FOAK plant apart Email: jpy1@hw.ac.uk RCCS, Heriot-Watt University from the KOH BPMED process. As the capital costs decrease with deployment, the source of electricity becomes more critical at the Gt-CO2 year -1 scale. Brazil has the highest natural gas price and highest natural gas carbon intensity, as shown in the ESI Table , which penalises the two processes using natural gas, i.e., KOH-Ca looping and MgO ambient weathering, primarily due to the gas price but also impacted by the carbon intensity, as seen in Figure . The methane leakage rate impacts the two processes that rely on natural gas, and thorough assessments of the leakage rate associated with any local supply chain to be used are required to integrate this data with techno-economic analysis.