Techno-economic modeling reveals scale-dependent biomethane costs in wastewater plants, highlighting operational expenditure as the primary cost driver.
Key Points
To estimate the technical production potential and levelized cost of biomethane (LCOB) from wastewater treatment plants utilizing Upflow Anaerobic Sludge Blanket reactors in Minas Gerais, Brazil.
Integrated population projections, wastewater generation rates, and coverage data with a temperature-corrected, COD-based methane balance model.
Computed LCOB using capacity-parameterized capital expenditure (CAPEX) and operational expenditure (OPEX) equations, assuming 70% upgrading efficiency and 92% plant availability.
Performed sensitivity analyses across a ±30% variation in OPEX, CAPEX, and discount rates to benchmark scale effects against larger reference municipalities.
Southern Minas Gerais demonstrated a total technical potential of approximately 1.19 million m³/year of biomethane, with LCOB ranging from US$0.49/m³ in Poços de Caldas to US$12.72/m³ in Cambuí.
Larger benchmark municipalities showed lower costs driven by scale, with Uberaba and Contagem achieving an LCOB of US$0.26/m³.
Sensitivity analyses revealed an inverse relationship between methane flow and production cost, identifying OPEX as the dominant cost driver, followed by CAPEX and discount rate.