Green biorefinery corresponds to sustainable processing of green biomass, such as grasses and legumes with a high content of leaf protein and soluble sugars to produce multiple products. The extraction of proteins from leaves represents an attractive alternative solution to the high European dependency on soy imports. A demonstration facility for R&D in Aarhus University Foulum, Denmark, optimizes the separation of protein-rich concentrates from green biomass. Besides the leaf protein concentrate, the facility also produces a fibrous pulp that can be used for ruminant feed, biomaterials, or bioenergy, and a nutrient-rich residual juice, that can be used for biogas production and fertilizer.
The green biorefinery was simulated using Aspen Plus V12 for the processing of grass-clover. The process included the maceration of the harvested biomass; mechanical fractionation into a fiber-rich press cake and a green juice; heat treatment of the green juice for precipitation of soluble leaf proteins; centrifugation and drying of the precipitated protein; and anaerobic digestion of the residual brown juice for biogas production. The simulation was validated based on data obtained from the demonstration plant, resulting in an overall yield of 40 % crude protein in the protein concentrate. The feasibility of the implementation of the biorefinery on a commercial scale was calculated using Aspen Process Economic Analyzer.