Optimization of Raw Material Composition in an Agricultural Biogas Plant

We analyzed the operation of a typical agricultural biogas plant in Hungary. Our aim was to optimize the composition of substrates for the biogas production and make a correct recommendation for completing feedstock recipes by considering the raw materials and technologies analyzed. The calculations were based on a very detailed database (including the daily operating data of 1673 days). Distribution of the biogas yields in summer and winter periods was normal based on the One-Sample Kolmogorov-Smirnov test, while the variance of data was homogeneous based on the Levene-test. Factor analysis of the biogas yield was performed with the Kaiser-Meyer-Olkin Measure of Sampling Adequacy probe (0.616) and the Bartlett's Test. According to the objectivity of our LP (linear program) model, we believe that a significant excess biogas yield (18-66%) could be achieved by the use of our model compared to the actual measured data. Although the amount of corn silage, grass silage, and the extract – as variables – was minimal in the recipe, they played a crucial role in the total biogas yield of the recipe because of their significantly higher organic matter contents and specific biogas yields. Our results could provide a reliable foundation for optimizing of the recipe in biogas plants with raw material base similar to the analyzed plants.