Economic analysis of biogas upgrading and utilization as vehicular fuel in South Africa

Economic and sensitivity analysis of a simulated biogas upgrading plant using a gas permeation software has been presented in this study. The effect of three process conditions on gas processing cost (GPC) were simulated. An increase in CO2 increased the GPC from $0.73 to $1.39/m3 of biomethane while an increase in feed pressure increased GPC from $0.65 to $1.16/m3 of biomethane. As the feed flow rate increased from 80-140 m3/h, the product flow rate increased from 46-100 m3/h while the GPC decreases from $0.79 to $0.39/m3 of biomethane. At optimized condition, the calculated GPC was $0.46/m3 of biomethane. The NPV, IRR and BCR for producing biomethane was R15,240,343, 22.41% and 2.0S respectively with a break-even in the 5lh year. Using CBG over gasoline, the end user saves 34% of annual fuel cost which is approximately R47,255 with a payback period of one year and three months for vehicle retrofitting. The fuel prices differential between gasoline and CBG as well as the overall savings, makes CBG attractive to the producer and end user.