Cow Manure Anaerobic Digestion or Composting – Energetic and Economic Analysis

The aim of the work was to compare composting technology and anaerobic digestion in the case of manure from dairy cows. The research was carried on the case study farm in Wielkopolska Region (Western Poland) specialized in milk production (600 cows). The results have shown that both analyzed scenarios can give the additional profits to a studied dairy farm. However, the anaerobic digestion can provide more than twice a higher profit (315.6 kEuro) comparing to the composting scenario (148 kEuro). In composting, the biggest part of the generated heat is lost and only 36% can be recovered, which influences on profit decreasing up to 75.5 kEuro (instead of 201.7 kEuro theoretically). The amounts of energy produced in anaerobic digestion technology by CHP unit is almost equal for electricity (1601 MWh) and for heat (1680 MWh). However, the electric energy has several times higher value than heat because of additional subsidies paid by the state.