Corn ethanol production with thin stillage anaerobic digestion for bioenergy recovery: A technical and economic evaluation

Autor(es)

Ziero, Henrique Di Domenico ; Ampese, Larissa Castro ; Buller, Luz Selene ; Costa, Josiel Martins ; Berni, Mauro ; Forster-Carneiro, Tania

• Tipo de documento: Artigo Científico
• Fonte: INDUSTRIAL CROPS AND PRODUCTS; v. 206, p. 11-pg., 2023-10-20.

Resumo

The generation of bioenergy from thin stillage in a corn ethanol mill provides a new perspective for the use of byproducts in a circular economy concept. Alternative technological routes for the corn ethanol by-products energy and nutrients recovery must be investigated to assess present and future decision-making toward economic and environmental indicators. The theoretical biogas production from an up-flow anaerobic sludge blanket (UASB) reactor in a corn-ethanol mill and the potential thermal and electrical power generation along with the avoided greenhouse gas (GHG) emissions were estimated for a large-scale industrial facility. This work aimed to assess the anaerobic digestion (AD) contribution to techno-economic indicators of a corn ethanol mill in three scenarios: 1) Standard corn-to-ethanol mill; 2) AD-CHP - thin stillage AD to produce biogas and its burning in a combined heat and power (CHP) system; 3) AD-BU - biogas purification to obtain and commercialize biomethane. The existent Brazilian market and fuels and biofuel policies place the system without AD in a slightly better position when analyzing financial indicators related to investment return. In contrast, the global energy and mass balances considering thin stillage AD showed that in the AD-CHP scenario, processing 1 ton of thin stillage would produce 10.37 m3 of biogas, which could generate 119.9 MJ of heat and 24.7 kWh of electricity in a CHP system, favoring a greener energy scenario. The energy recovered from biogas returns to the industry, supplying 7.15% of the heat required for steam production and 52.74% of the electricity requirement for industrial processing. As a renewable energy source, biogas would replace fossil sources for energy generation avoiding GHG emissions. Extrapolating the results of the present work to the Brazilian national scale, the biogas yield from the corn-toethanol industry would be 179.68 million m3 , the thermal energy generation from biogas could mitigate 125,574.42 ton CO2eq, and the electricity replacement could mitigate 58,193.02 ton CO2eq. Besides the mentioned energy generation and environmental benefits, the financial indicators for the examined scenarios showed that the Brazilian market and public policies related to biogas/biomethane are constraints to overcoming to larger adoption of AD by the corn-to-ethanol industry. (AU)

• Processo FAPESP: 21/03950-6 - Hidrólise subcrítica e digestão anaeróbia para produção de açucares e biogás a partir do bagaço de maçã proveniente do processamento de suco
• Beneficiário: Josiel Martins Costa
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado