were calculated according to the ESI Table . Next, the EPC costs were escalated to those of a FOAK commercial project using the process and project contingencies, and owner's, spare parts, and start-up costs to arrive at the total overnight cost (TOC), as defined by Rubin et al. and detailed in the ESI Tables . The inclusion of appropriate project and process contingencies, which are representative of the development stage of a technology and the level of detail in the project design, is lacking in all but a very few ex-ante techno-economic studies of climate change mitigation process technologies. The project contingencies take into account costs not considered in the analysis due to the preliminary level of project specification. Meanwhile, process contingencies account for any uncertainty surrounding capital costs on account of the technology maturity of a process and the cost of upscaling that accompanies this. Therefore, the process contingency is higher for low TRL technologies as they are more likely to incur extra costs whilst developing through unforeseen issues that must be addressed with process adjustments or a change of operation. The process contingencies used for each technology (as function of their TRL) can be found in Table .