Renewable Energy, Vol.146, 1976-1983, 2020
Strategies for energy recovery and gains associated with the implementation of a solid state batch methanization system for treating organic waste from the city of Rio de Janeiro - Brazil
This work aimed at studying strategies for energy recovery from a demo-scale solid state batch methanization (SSBM) system, denominated TMethar, implemented in the city of Rio de Janeiro, Brazil, besides evaluating the economic and environmental gains associated with different biogas uses. The demo-scale plant is capable of treating 23.5 t d(-1) of the organic fraction of municipal solid waste (OFMSW) and is composed by the following main units: i) six SSBM reactors; ii) a hybrid reactor that can be operated either as SSBM or as thermal-drying reactor; iii) a completely mixed anaerobic reactor for leachate stabilization and inoculum production; and iv) units for biogas conditioning, treatment and utilization. The biogas produced in the TMethar system will be primarily used as fuel to run the combined heat and power (CHP) engine for electricity generation, but its use for biomethane production was also considered in this study. Much higher economic gains could be achieved with the use of biogas for biomethane production ((sic)43.t(-1)OFMSW against (sic)19.t(-1)OFMSW when used for electricity generation), the same occurs in terms of GHG reductions. The overall avoided GHG emissions achieved by replacing diesel by biomethane in the waste transportation trucks (537 kgCO(2eq).t(-1)OFMSW) is over 14% higher than the GHG mitigation achieved by replacing electricity from the power grid to renewable electric energy produced in the CHP engine fuelled on biogas (462 kgCO(2eq).t(-1)OFMSW). Overall, it can be concluded that both strategies for energy recovery from biogas produced in the TMethar would enable considerable environmental and economic benefits for the city of Rio de Janeiro. (C) 2019 Elsevier Ltd. All rights reserved.