12-08: Lowering cost of enzymatic hydrolysis of pretreated biomass materials using enzymes produced on-site in the biorefinery

Production of biofuels from cellulosic materials will often involve the addition of external enzymes to hydrolyze the materials into sugars after pretreatment. The efficiency of commercial cellulytic enzymes has increase significantly over the last years. Still the cost of enzymes is high and somewhat prohibitive for large scale production of biofuels without the simultaneous production of a valuable high-end bio-product. Production of cellulytic enzymes in centralized facilities demands an expensive growth medium and the overall protein concentration produced is far lower than for starch-degrading enzymes meaning that the amount of enzyme needed is high. We will discuss the potential of using on-site enzyme production integrated into the biorefinery. Assuming that the capital cost for enzyme production is kept constant, the cost reduction of on-site enzyme production compared to use of conventional enzymes boils down to a significant lowering of the operation cost for enzyme production due to the use of slip streams from the biorefinery as part of the growth medium for enzyme production, the direct use of the fungal enzyme fermentation broth during hydrolysis within any processing as well as the avoidance of transport cost for the enzyme preparation.  Another significant factor for cost reduction during on-site enzyme production is the elimination of profit needed by the enzyme provider.  The presentation will show data on hydrolyzing pretreated biomass material (corn stovers, pine and fir) with enzymes produced on-site by slip-streams from our cellulosic pilot facility and will discuss the perspective of cost for scaling up this process.