Techno-economic assessment of bioenergy and fertilizer production by anaerobic digestion of brewer’s spent grains in a biorefinery concept

This study presents a techno-economic assessment of bioenergy and fertilizer production by anaerobic digestion (AD) of brewer’s spent grains (BSG). Simulations were performed by integrating the production of biomethane, electricity, thermal energy, and fertilizer for five revenue conditions. BSG generation from different brewery industrial scales was considered. Results showed that investing one million USD for a treatment capacity of 137 t BSG d−1 makes it possible to recover up to 350,000 USD y−1 when selling electric energy to the grid, using the thermal energy for the facility self-consumption, and selling the fertilizer for agriculture application. The economic analysis for this scale resulted in a payback time of 3.76 y, ROI of 23.68%, and NPV up to 1.5 million USD. The revenue considering biomethane and fertilizer was profitable and amenable for a real application, with a payback time of 3.67 y and IRR up to 20%. From the sensitivity analysis, the selling price of fertilizer, biomethane, electricity, and heat were the most important variables affecting the project’s economic viability. Beyond, project implementation from equity could upgrade the feasibility. Ultimately, the waste management system with bioenergy recovery and fertilizer production from the AD of BSG is profitable and could be suitable for an oncoming implementation in breweries. [Display omitted]