Vacuum Evaporation of a Liquid Digestate from Anaerobic Digestion: A Techno-economic Assessment

This study examines whether vacuum evaporation (VE) is a cost-effective way for biogas plants to reduce the volume of liquid digestate they must handle. VE can significantly cut transport costs by shrinking the amount of material that needs to be moved, but its advantages depend heavily on each plant’s specific circumstances. It becomes more profitable when transport distances are long, while high electricity feed-in tariffs make it less attractive because the evaporator consumes power that could otherwise be sold. Under typical conditions, VE is economically worthwhile mainly when digestate needs to be transported more than about 20 km. Overall, the study concludes that VE is not suitable for every biogas plant and that careful economic analysis is necessary before investing.