Circular bioeconomy of coffee industries: Energy and techno-economic approach based on biogas and biomethane production

Abstract

The coffee industry is one of the most valuable and complex commodities in the world, surpassed only by the petroleum industry. Coffee roasting consumes a significant amount of energy that generates biodegradable organic waste. This paper aims to perform a technical, energy, and economic analysis on the valorization of waste from the coffee roasting industry (CRi) for the production of biogas and biomethane and then to verify the economic viability of four scenarios, incorporating the waste in a circular bioeconomy model. The results show that the potential biogas production was 137.26 Nm3 biogas/ton and biomethane 89.22 Nm3 CH4/ton fresh matter. The highest energy production was from the anaerobic digestion technological maturity scenario (AdMS), with a production of 113.68 MWh/a of electricity and 163.99 MWh/a of heat from the CHP. The amount of electricity replaced in CRi by biogas generation was 2.07% for the traditional anaerobic digestion scenario (TAdS) and 2.20% for the AdMS. The amount of heat replaced in CRi by heat generation was lower in the AdMS scenario, with a value of 1.10%. The study concludes through the economic analysis that the AdMS is the one that best fits the valorization of coffee waste with a net present value (NPV) of 17,930 USD and an internal rate of return (IRR) of 17.53%.