From 2020 toward 2050, the external forcing mechanism in the supply model replaced 5% of the existing capacity every year with production technologies that had lower emissions. After the forced replacement, plants were further built or decommissioned based on the gap between the production capacity and the demand for each year. Note that certain new technologies were not expected to become available until 2030 (Table ). Note further that scope 3 category 12 emissions (explained later) were included in the calculation of the total amount of emissions for each pathway but were excluded when production technologies were selected in the NFAX scenario; therefore, they were not part of the optimization. This approach of applying the external forcing mechanism starting in 2020 did not guarantee that emissions would reach precisely net zero by 2050, but it did ensure continuity from 2020 to 2050 in terms of total production capacity and the mix of production technologies. As such, this approach was a combination of backcasting and forecasting, in which transition pathways start with the current status and approach the desired target status by 2050. In addition, this model assumed domestic production with a plant size of 3,000 tons/day to meet domestic demand and net exports. The impact of imports from explicit production abroad was qualitatively evaluated outside of the model and discussed in the Discussion section.