The method is called the 'hybrid method'. It combines bottom-up engineering economic studies, to estimate the cost of a FOAK plant, with technological learning projections accounting for cost reductions with cumulative technology deployment as a result of innovation, learning by doing, learning by using, and economies of scale, among others. Critical to this method is a sound FOAK cost estimate for the low TRL technology, which should include the cost escalations from the current TRL to the FOAK plant, i.e., TRL 8 or 9. In particular, the correct application of this cost escalation is missing in the existing literature. Consequently, the few academic studies that project the costs of DACS into the future using technological learning commence from a starting point that is too low (sometimes by a * Throughout this paper, t always refers to metric tonnes. 4 Email: jpy1@hw.ac.uk RCCS, Heriot-Watt University membrane electrodialysis (BPMED), c) solid sorbent DAC using temperature vacuum swing adsorption, and d) MgO ambient weathering with regeneration via calcination, presented in Figure . The key contributions of this study are: i) the first time the hybrid costing method has been correctly applied to DACS, ii) the investigation of DACS economics across different countries and regions, iii) the novel evaluation of the effect of different policy instruments on DACS costs, and iv) the inclusion of four different DACS technologies, to span a wider solution space, and evaluate these on a harmonised costing basis, including CO2 compression, transport, and permanent geological storage to complete the chain for net-CO2 removal.