Brazilian bioenergy generation from cattle and pig manure: An economic life cycle assessment

Renewable energy from biogas derived from agricultural waste offers strong potential for sustainable rural development in Brazil. This study conducts the first comparative economic life cycle assessment (E-LCA) of 1 kWh of electricity generated from cattle and pig manure in small-scale systems in the Brazilian Midwest. Following ISO 14040 and 14044 standards, the analysis covered goal and scope definition, inventory, impact assessment, and interpretation, to provide robust insights for managers and policymakers. Eight scenarios were compared, integrating digestate use and two electricity generation models with covered lagoon biodigester technology. Results showed that pig manure scenarios are more economically viable, achieving generation costs as low as US$0.01/kWh, while cattle manure reached US$0.09/kWh. Distributed generation models were up to 38.5 % more profitable than individual systems. Moreover, including a secondary lagoon and using digestate as biofertilizer increased the internal rate of return by up to 80 %. These findings underline the urgent need for policies to foster energy transition and carbon reduction in Brazil, especially in rural and agro-industrial sectors still dependent on conventional energy sources. Promoting small-scale biogas adoption is a crucial step toward achieving Brazil's climate goals and its Paris Agreement commitments.