4. Conclusion
The investment of biogas as energy source for electricity power generation in small scale ranch that maintain 18-
54 cows and produce 10-30 kg manure/cow/day in Indonesia is economically acceptable for all farmer investment
condition. The feasibility will be higher in the case when land investment and labor cost is not required. Labor cost
significantly influence profit and economic feasibility much higher than the influence of land investment. In order to
obtain the higher profit, it is suggested that the daily digester operation is done by the farmers themselves to reduce
labor operational cost. The result of analysis show that the value of IRR, PI, ARR, and PP are approximately of
18.6%-32.3%, 1.5-2.2, 15.4%-29.4%, and 3.3-5.1 years respectively.