BE-Sustainable. 2014. Empyro BV breaks ground of its biomass to liquid pyrolysis plant. Ensyn. 2016. Scale-up & Optimization BETO Workshop. BTG. Pyrolysis oil properties. Environment Canada. 1999. Bunker C Fuel Oil. Cellulose is an important structural component of the primary cell wall of green plants. It is an organic compound with the formula (C6H10O5)n, a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. The basic chemical formula is the same as for starch with the difference being that the “n” is much larger for cellulose. If the cellulose can be broken down into the glucose molecules then those can be fermented into ethanol and the rest of the process is similar to the 1st generation starch ethanol process. Contact Information Don O’Connor – (S&T)2 Consultants Inc. Brief Technology Description The cellulosic feedstock, which could be straw, corn stover, bagasse, or wood residue is generally subjected to a pretreatment stage to separate the cellulosic portion of the material from the lignin and make the feedstock amenable to hydrolysis. The pretreatment stage may use acid and or steam to accomplish the goal. The hydrolysis stage breaks down the cellulose molecules into smaller polysaccharides or completely into glucose units; this is a hydrolysis reaction. Hydrolysis can be carried out with cellulase enzymes or with acid. Most process developers are using enzymes. Following the hydrolysis stage a yeast is added to convert the sugars into ethanol and carbon dioxide. The “beer” is then distilled to remove ethanol and water from the unfermented solids. A second distillation column to reach 95% ethanol and 5% water is followed by a molecular sieve to produce anhydrous ethanol by most process developers. The unfermented solids have little value as animal feed and process developers generally convert the material to energy (thermal and electricity) to be used in the process with any excess being exported to the grid. A typical process flow diagram is shown in the following figure. Figure 81 Cellulosic Ethanol Process Input The primary input is the cellulosic feedstock, along with water and the chemicals used in the process. The quantity and type of feedstock vary between process developers.
The EU Sub on Advanced Biofuels reported plant sizes in the range of 100 to 200 MW and capital costs of €1,850 to 3,450/kW depending on the scale (€1.00/litre to €1.85/litre). The capital costs range from €0.75/litre (NREL) to €2.70/litre (Värmland). Operating and Maintenance Costs Anderson only presented the combined operating and maintenance costs (Costs for wages, insurance for employees and chemical, water and ash disposal) of €0.10/kg (€0.08/litre). NREL did not provide a breakdown of the operating costs. Start-up Costs The start-up costs are included in the costs reported. Technology Specific Data Some the properties of methanol are shown in the following table. 102 Methanol Properties Property Value Density, kg/m3 791 LHV, MJ/kg 19.9 LHV, 15.7 Oxygen content 50% Blending Octane number ~115 point, C 12 The quantitative data for the biomass to methanol process are summarized in the following Table 103 Bio Methanol Datasheet Technology Bio Methanol 2015 2020 2030 2050 Uncertainty (2020) Uncertainty (2050) Note Ref Upper Lower Upper Energy/technical data Typical total plant size 1,000 t Methanol/year 100 100 200 300 50% 200% 50% 125% A, B 3, 5, 6 Typical total plant size, MW 65 65 130 195 50% 200% 50% 125% A, B 3, 5, 6 Inputs Feedstock Consumption, MWh/MWh Total Input 1.0 1.0 1.0 1.0 90% 150% 90% 120% 1 Outputs Methanol Output, MWh/MWh 0.58 0.58 0.61 0.65 100% 133% 100% 133% D 1 Co-products Output, MWh/MWh Input 0.25 0.25 0.25 0.25 0% 100% 0% 100% D 1 Forced outage (%) 0 0 0 0 Planned outage (weeks per year) 2 Technical lifetime 25 Construction time 2 - 3 Financial data