Biogas Clean-up and Utilization

The economic use of energy from biogas generated in anaerobic biodigesters installed in the sewage treatment plants owned by SABESP is described in this paper with evaluation of its advantages in vehicular use. The clean-up process and use of biogas were designed based on results obtained from a pilot plant in operation since 1983. The biogas is sweetened through water scrubbing, with reduction of CO₂ and humidity, to attain acceptable levels for consumption by vehicular engines. The resulting methane gas is odourized and compressed in cylinders by high pressure compressors. The vehicles are adapted to compressed methane, with installation of high pressure cylinders, pressure reducing valves, methane/air mixers, valves and pressure gauge for maximum operation safety. Filling of vehicles (refuelling) is done in an appropriate station and transfer of methane to the vehicle is by difference of pressure.