Avaliação do potencial de produção de biogás utilizando resíduos vegetais hortícolas como resposta as mudanças climáticas

Abstract

The present study, entitled Assessment of the Biogas Production Potential from Horticultural Waste (Cabbage and Lettuce), aimed to analyze the technical and social feasibility of using horticultural residues for biogas generation, characterizing their physicochemical properties and comparing the energy performance of biogas with other fuels commonly used in urban and rural contexts of Mozambique (firewood, charcoal, and liquefied petroleum gas – LPG). The research was carried out in two complementary phases: (i) an experimental phase, which included physicochemical characterization of the residues, assembly and feeding of 10 L biodigesters for boiling and combustion energy tests; and (ii) a participatory phase, involving the construction of a 20 L biodigester in the field with local farmers and conducting a survey to assess energy practices and perceptions regarding biogas use. Characterization results revealed high moisture contents (95.41% in cabbage and 88.70% in lettuce), low mineral fraction (ash < 2%), and near-neutral pH (5.85–6.00), all favorable conditions for anaerobic digestion. In energy performance tests, firewood and charcoal showed higher thermal power (1.9–2.07 kW), but biogas demonstrated better relative efficiency and lower specific consumption, indicating more efficient use. The surveys indicated that 46% of farmers use combinations of LPG and charcoal, followed by firewood and charcoal (34%), 60% of the producers interviewed had already heard about renewable energy, and 88% expressed willingness to adopt biogas. The participatory construction of the 20 L biodigester in the field demonstrated both the technical and social feasibility of the technology, as well as its potential for replication in other communities. The study demonstrated that cabbage and lettuce residues have potential for biogas production, and that adopting this technology may contribute to energy diversification and reduction of environmental impacts.