cellulase used in this study was estimated to be approximately 10 Yuan of Chinese RMB, approximately $1.60 per kg of cellulase, although this price was not tagged to cellulase product and all cellulase products were sold under much higher prices. Based on this estimation, the cellulase cost was calculated to be $2517.79,
$2222.22, and $375.48 per ton of increased ethanol product. Clearly, the Co-SSF process in Case 3, that is the simultaneous co- saccharification of cassava starch/cellulose and ethanol fermenta- tion process, demonstrated great advantage in cutting the cellulase cost. On the other hand, the cellulase costs in Case 1 and Case 2 were much more expensive than the fuel ethanol selling price (approximately $1,000 per ton of fuel ethanol) thus the profit from the two cases were negative.