Abstract
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 2.05
respectively with a break-even in the 5th 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.