Techno-economic Feasibility of Biogas Utilization for Grid Connected Biogas and Solar PV System: Case for Kaliti Waste Water Treatment Plant
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Date
2023-02
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Addis Ababa University
Abstract
Wastewater treatment plants consume large amount of energy, which in turn will lead to incurring higher operating cost. On the contrary, they have a significant amount of energy potential through treatment processes especially biogas produced from anaerobic treatment phases. Utilizing this energy potential will help to supply power for the plant from its as well as to reduce operating costs.
This study is conducted in Kaliti wastewater treatment plant that is receiving septic & latrine wastes via trucks and truncated sewage pipes. During the process of treatment, one of the products is biogas, which is not being converted to useful application. In this study, assessment of demand & resources for the plant is done & the peak primary load is about 111 kW and the daily primary energy demand of about 1278 kWh/day. Maximum & minimum monthly average hourly solar Ground Horizontal Irradiance (GHI) of 5.47 kWh/m2/day & 3.71 kWh/m2/day respectively and it has a daily average biogas production of 3903 Nm3/day. Modeling and Optimization of energy systems is done by Hybrid Optimization of Multiple Energy Resources (HOMER) software using biogas resource, solar resource, diesel gen-set and main grid by categorizing off-grid and grid connected systems.
From all the systems investigated and compared, off-grid systems are found by having highest Net Present Cost & Cost of Energy. Grid-PV scheme with Net Present Cost of 1.81M＄& Cost of Energy of 0.329＄/kWh and Grid-biogas scheme with Net Present Cost of 1.8M & Cost of Energy of 0.403＄/kWh are the 1st and the 2nd ranked. And Grid-biogas scheme is found optimal system due to its smaller initial capital and no excess electricity.
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Keywords
Biogas Utilization, Biogas, Solar PV System, Waste Water Treatment Plant