. Methods
Economic analysis is done based on the biogas installation scheme presented in Fig. 1, the operation needs, and
the price of the products. The analysis is limited only in the utilization of biogas as energy source for power
generation and not for others purpose like cooking. The analysis also considering the value of solid fertilizer resulted
from the digestion sludge.
2.1. Data required
For analysis purpose, there are needed to calculate the amount of cow manure have to be fed daily to the digester
to generate some amount of power, the amount of water to dilute the manure, the amount of fertilizer produced, and
the volume of digester to convert manure to biogas. The calculations are done based on the amount of power want to
be generated.
Based on previous research that 100 gram or 0.1 kg of cow manure will potentially produce biogas that can be
used to generate power of 0.008973 kWh [1], the rate of cow manure have to be fed to digester to generate some
amount of electrical energy, ms (kg/day), can be calculated by: