Integrated lignocellulosic value chains in a growing bioeconomy: Status quo and perspectives

Lignocellulose is the most abundant biomass on Earth, with an estimated 181.5 billion tonnes produced annually. Of the 8.2 billion tonnes that are currently used, about 7 billion tonnes are produced from dedicated agricultural, grass and forest land and another 1.2 billion tonnes stem from agricultural residues. Economic and environmentally efficient pathways for production and utilization of lignocellulose for chemical products and energy are needed to expand the bioeconomy. This opinion paper arose from the research network Lignocellulose as new resource platform for novel materials and products funded by the German federal state of Baden-Wurttemberg and summarizes original research presented in this special issue. It first discusses how the supply of lignocellulosic biomass can be organized sustainably and suggests that perennial biomass crops (PBC) are likely to play an important role in future regional biomass supply to European lignocellulosic biorefineries. Dedicated PBC production has the advantage of delivering biomass with reliable quantity and quality. The tailoring of PBC quality through crop breeding and management can support the integration of lignocellulosic value chains. Two biorefinery concepts using lignocellulosic biomass are then compared and discussed: the syngas biorefinery and the lignocellulosic biorefinery. Syngas biorefineries are less sensitive to biomass qualities and are technically relatively advanced, but require high investments and large-scale facilities to be economically feasible. Lignocellulosic biorefineries require multiple processing steps to separate the recalcitrant lignin from cellulose and hemicellulose and convert the intermediates into valuable products. The refining processes for high-quality lignin and hemicellulose fractions still need to be further developed. A concept of a modular lignocellulosic biorefinery is presented that could be flexibly adapted for a range of feedstock and products by combining appropriate technologies either at the same location or in a decentralized form.