The industrial deployment strategy
The new pretreatment concept is well adapted to the business model of small-scale industrial plants. Indeed, the processing capacity for a typical industrial twin-screw extruder is a few tons per hour. Today one can buy off-the-shelves twin-screw extruders rated at about 30 000 tons per year processing capacity. This figure can be considered as the lower and unit size of a range of small-scale industrial plants which processing capacities could vary from 30 000 to 120 000 t/y (i.e. 120-250 kt and above 250 kt, being considered as medium and large size production plants, respectively). Increasing capacity can be easily achieved by multiplying the number of pretreatment lines in the plant (which might even be necessary in case of processing different biomasses at the same time) or by designing higher scale equipment. This strategy allows flexibility when designing plants and saving on the engineering costs for both the operator and equipment manufacturer.
Indeed, the homothetic design of a range of extrusion equipment allows for simplified engineering requirement through a direct volumetric extrapolation from one size equipment to another size. It also guaranties the same level of performances when scaling-up the production rates. Moreover, a strategy based on smaller size units reduces the scale factor from demonstration units (TRL 6-7) to first-of-a-kind plants (TRL 8) (i.e. typically x 60 for large units to x 10 for smaller units). The assumption that such small-scale oriented strategy increases the opportunities for exploiting scattered local feedstock and draws the interest from the biomass producers was verified during the project Babethanol. The techno-economic and environmental viabilities must be reached at the lowest or unit processing scale of 30 000 tons equivalent dry biomass per year. This is why this production level will be used in the project as the threshold capacity to reach techno-economic and environmental performances with the industrial model evaluation.