As shown in Figure , the two ME supply scenarios that sought the most economical solution relied on fossil-based feedstock for more than 95% of their carbon source. In these scenarios, the carbon in waste that was not recycled was incinerated and sequestered by CCS or disposed of in landfills. In addition, off-gas (mostly methane) from crackers was used as fuel and sequestered via CCS. The ME supply scenarios selected solutions based on fossil feedstock and CCS for the most part because they were less expensive than processes utilizing alternative feedstocks. The NFAX2 supply scenario did not use CCS but was otherwise identical to the NFAX scenario. This scenario provided insight into cases in which CCS was found prohibitively expensive or impractical in Japan.