Multiparameter-analysis of CO2/Steam-enhanced gasification and pyrolysis for syngas and biochar production from low-cost feedstock
Rafael Benjamin Werneburg Evaristo, Ricardo Ferreira, Juliana Petrocchi Rodrigues, Juliana Sabino Rodrigues, Grace Ferreira Ghesti, Edgar A. Silveira, Mário Costa
Abstract
The disposal of spent coffee grounds (SCG) and brewers' spent grains (BSG) has become an environmental issue. Thus, the waste-to-energy valorization of these two low-cost feedstocks was performed via gasification and pyrolysis to assess their potential as syngas and biochar fuels. The processes’ optimum conditions were investigated by a multiple-criteria decision support method. Firstly, both raw materials were gasified at 1000 °C with O2/N2, O2/CO2/N2 and O2/H2O/N2 atmospheres. The characteristics and energy performance of the producer gas were evaluated. In addition, the exergy analysis of green-H2 production was assessed. The pyrolysis experiments were conducted at 300, 500 and 700 °C, followed by a comprehensive characterization of the biochar properties and its combustion behavior. The syngas production based on CO2/Steam-enhanced gasification has indicated clear energetic and exergetic improvements against O2/N2 with a promising increase of 32.97% LHVsyngas for BSG. Obtained biochar possesses favorable fuel characteristics promoting an HHV enhancement up to 19.42% (SCG) and 83.11% (BSG). Furthermore, the combustion index indicated a great potential of using SCG and BSG as solid biofuel for straightforward application to heat generation in small-scale systems. Therefore, syngas and biochar characteristics encourage feasible biofuels from low-cost feedstocks for energy generation.