Reducing biogas emissions from village-scale plant with optimal floating-drum biogas storage tank and operation parameters

Highlights: • Performance of a village-scale plant with semi-continuous feeding was analyzed. • Models, including biogas production rate and biogas consumption rates, were established. • A biogas flow chart with key parameters was proposed. • Optimal tank and appropriate operation could guarantee reduced biogas emissions. - Abstract: In this study, an approach to optimize the components and operation of biogas plant systems, which temporarily stores biogas in floating-drum biogas storage tank (BS) and feeds in a semi-continuous manner, was developed. First, the parameters of biogas production and consumption were characterized into mathematical models, and estimated with a 1-year operating data set of a village-scale biogas plant (fermentation volume, 80 m³). Then, the established models, which included biogas production and consumption rates, were used to determine the optimal BS volume and operation parameters for improving biogas plant performance. In contrast to the biogas usage level achieved with the established BS (76.4%), that obtained with an optimal system could reach up to 85.7% and the feeding frequency for a 1-year operation could be decreased 6.5 times. Our proposed approach exhibited a number of attractive features, including accurate determination of parameters, reduced biogas emission, and cost efficiency, which may not only enhance biogas benefits, but also increase economic and environmental feedback on village-scale biogas plant operation.