A Feasibility Study of Continuous Stirred Tank Reactor (CSTR) Biogas Network from Water hyacinth at Hin Moon, Bang Len, Nakhon Pathom Province

The objective of this research was to study the economical value of investment in a biogas production system with a size of 100 cubic meter using 2,298.5 kilograms of water hyacinth per day to replace LPG in households. The project duration is 20 years, calculated by the total workload and construction cost. The data were collected on construction costs, revenues and related expenses throughout the project life. Then, the data was analyzed using common financial return indices such as net present value (NPV), internal rate of return (IRR), benefit cost ratio (BCR), payback period (PB) and sensitivity analysis. The analysis was divided into 3 case studies. The project owner invested all money, the government supported all projects, and the project owner borrowed money for investment in case study 1, 2, and 3 respectively. The results showed that case study 1 has net present value of128,903.86 baht, internal rate of return of 5.02%, benefit cost ratio of 1.02 and payback period of 12 years 5 months 12 days. Case study 2 has net present value of 763,280.74 THB, benefit cost ratio of1.12, and payback period of less than 1 year and internal rate of return could not be found because the project was supported by government investment. Case study 3 has net present value of -2,167,385.79 THB, internal rate of return of -13%, benefit cost ratio of 0.71 and this project cannot payback within 20 years. Therefore, case study 1 and case study 2 significantly influenced this project were worthwhile to invest in biogas production system using continuous stirred tank reactor (CSTR) from water hyacinth.