Proposal for biorefineries based on mixed cultures for lignocellulosic biofuel production: a techno‐economic analysis

Abstract

An innovative conceptual design is introduced for lignocellulosic-based biochemical platform biorefi neries using three mixed-culture bioprocesses that sequentially disintegrate each polysaccharide fraction into different target biofuels: hydrogen, methane, and fuel butanol. This mixed-culture biorefi nery circumvents the use of corrosive chemicals, energy-demanding pre-treatments, costly enzymes, separate units for saccharifi cation and fermentation, steam for sterilization, and expensive steel bioreactors. The concept mimics bioprocesses occurring in nature to degrade complex substrates. A technoeconomic analysis of these biorefi neries is carried out focusing on the impact of residence times (8-120 h) and butanol titers (10-20 g/L) of the production of acetone-butanol-ethanol (ABE) on the total production costs (TPC) of butanol. The design includes electricity-steam cogeneration from gaseous biofuels and lignin, as well as solvent purifi cation. Simulation results show that the highest butanol titer impacts TPC to a greater extent than the lowest residence time. TPC range from US$1.04 to US$1.27 per liter of butanol in facilities with 20 g/L of butanol irrespective of residence time. The end-use energy ratio for all facilities was close to 2 or higher. These biorefi neries display lower energy consumption and environmental impacts than conventional second-generation lignocellulosic biofuels biorefi neries, and its cost structure is determined by the substrate similar to bioprocesses with mature technology. Finally, this study provides an insight to the advancements made in realizing viable mixed-culture fermentations for different fi elds of biotechnology and therefore might be encouraging for further studies of lignocellulosic biorefi neries based on mixed cultures.

Techno‐economic learning in biorefinery research; a meta‐level perspective of three exemplary cases

“…In addition to lignosulfonates, kraft lignin is the most abundant technical lignin, and stakeholders assume that it will become the most important one in terms of its availability and market supply in the near future 20 . Kraft lignin may play an important role as a renewable feedstock in the future for the production of a variety of chemicals and chemical products, such as phenols, 21,22 bioplastics, 23,24 carbon fibers, 25 and biofuels 26 …”

“…20 Kraft lignin may play an important role as a renewable feedstock in the future for the production of a variety of chemicals and chemical products, such as phenols, 21,22 bioplastics, 23,24 carbon fibers, 25 and biofuels. 26 Like the processing of biomass to produce biodiesel, the processing of biomass to produce cellulosic ethanol and kraft lignin are developments that have occurred in the past three decades. These technologies are not yet operating in an even competition with their fossil-based counterparts.…”

Continuous hydrogen production from glucose/xylose by an anaerobic sequential batch reactor to maximize the energy recovery efficiency

“…On the one hand, H 2 has high energy content, and as a biofuel, it does not cause CO 2 emission; 1 on the other hand, as a substrate for bio-H 2 production, lignocellulosic feedstock is abundant, renewable and does not compete for land used for food or feed production. 2 In the past few decades, efforts made on the biological conversion of lignocellulose to H 2 were mainly focused on breaking the recalcitrant heteropolymeric structure of lignocellulose as well as liberating monomeric sugars (mainly a mixture of glucose and xylose despite the variations in the carbohydrate composition of different lignocelluloses) embedded in cellulose and hemicellulose to the maximum. However, when both glucose and xylose are present, most microorganisms generally metabolize glucose only because of the carbon catabolite repression effect.…”