Harnessing Biogas from STPs for Sustainable Energy: A Techno-Economic Study

The pursuit of affordable renewable energy sources has increased interest in biogas. One of the sources used to produce this fuel type is organic waste, which turns what would have been discarded into a valuable product. This study evaluated the potential and economic feasibility of generating electricity using biogas produced in a sewage treatment plant. The plant currently operates with an average inflow of 25 litres per second, producing an estimated 9.69 cubic meters of biogas per hour. The electricity generated has a potential of 125.22 megawatt-hours per year, meeting 47.4% of the plant's electricity needs. The average cost of the electricity produced ranges from 0.09 to 0.12 R$/kWh, depending on the interest rate used. The economic analysis suggests a maximum payback period of two years for the initial investment, with a net present value (NPV) of R$ 47,687.49 over the project's 20-year lifespan. Additionally, extrapolating the results to account for future expansion of the sewage treatment plant based on the total population in the region served by the sewage system reveals even more promising results.