The subject of the study is the profitability of selected substrates used in agricultural biogas plants. Dry matter, organic dry matter, COD, total nitrogen, organic acids, biogas potential and methane content in biogas were investigated in the analyzed substrates. The measurements for biogas potential were performed as a batch-test at 38°C. The results enabled to estimate the energy balance, which was the basis for economic calculation for each of the analyzed substrates. As a result of the analysis it was found that maize silage provides the highest energy gain, while the lowest energy gain is acquired from cattle slurry and whey.

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