Cost-effective production of biogas from manure – retrogas project

Transport of large quantities of low concentrated swine manure (total solids around 5-7%) to biogas plants represents a significant proportion of the operating costs for co-digestion plants. Together with the increment of the prices of the industrial effluents that are used for codigestion, this is the main reason for the poor economic performance of biogas plants in Denmark.
The idea of increasing the methane productivity of the manure has triggered the development of new separation technologies for being applied before the anaerobic digestion of the swine manure. Thus, the solid and liquid fractions of the manure could be used to centralized biogas plants for methane production and as fertilizer on the farm, respectively. Unfortunately, the manure transportation systems today are designed for handling of liquid material and are useless for solid material transportation. A solution to that would be the liquefaction of the solid fraction of manure prior the transportation in order to use the already existent infrastructure.
This presentation focuses on the RETROGAS project (funded by the Energy Technology Development and Demonstration Programme of the Danish Energy Agency) that aims at the development of new separation and liquefaction technology in order to make the anaerobic digestion of swine manure cost efficient and viable.