Economic performance of biogas production and use from residues co-digestion in integrated 1G2G sugarcane biorefineries: Better electricity or biomethane?

•Economics of co-digesting 1G and 2G sugarcane-derived residues was assessed.•Co-digestion economically outperformed mono-digestion regardless of the biogas use.•Electricity from bagasse is economically unfavorable compared to biogas production.•The NPV for bioCH4 is 5-fold higher than for bioelectricity in co-digestion.•Electricity and bioCH4 can be produced simultaneously in a sugarcane biorefineries. Recovering bioenergy through anaerobic digestion (AD) has become the most attractive waste management approach in modern industrial plants, because both the environmental adequacy and the provision of clean biogas-derived energy can be successfully met. Recent investigations have particularly shown the energetic benefits of residue co-digestion in sugarcane biorefineries, which significantly enhances biogas production compared to mono-digestion schemes. This work carried out an economic analysis to assess the feasibility of producing biogas from residues co-digestion in an integrated 1G2G (first and second generation) ethanol biorefinery and its application in electricity and biomethane (BioCH4) production. Scenarios considered the mono-digestion of 1G vinasse in the season (MD1-base scenario), the mono-digestion of 1G vinasse in the season followed by the mono-digestion of 2G vinasse in the off-season (MD2), the co-digestion of 1G vinasse, filter cake and deacetylation liquor in the season followed by the co-digestion of filter cake and deacetylation liquor in the off-season (CD1), and finally the co-digestion of 1G vinasse, filter cake and deacetylation liquor in the season followed by the mono-digestion of 2G vinasse in the off-season (CD2). The scenarios comparison aimed to investigate the potential to implement year-round biogas production in sugarcane processing plants. The results showed that co-digestion-based scenarios (CD1 and CD2) had the best performance for producing both electricity and BioCH4 from biogas, with the higher profitability related to the latter. Scenario MD1 scenario presented a negative net present value (NPV) for both electricity and BioCH4 production, whilst only BioCH4 production would be profitable in scenario MD2. The NPV for electricity production in scenario CD2 reached USD 9 million (4-fold higher than mono-digestion of 1G vinasse reported in the literature), whilst a peak of USD 45 million was calculated for BioCH4 production. In addition, the current bioelectricity production from bagasse burning showed to be much more