Is it possible to convert lignin into valuable products? New research from the U.S. Energy Department's National Renewable Energy Laboratory (NREL) suggests that it is.

The NREL-led study explores an innovative method for upgrading the plant-derived polymer and demonstrates a concept that provides opportunities for the successful conversion of lignin into a variety of renewable fuels, chemicals and materials.

Lignin is a heterogeneous aromatic polymer that plants use to strengthen cell walls. It represents up to 30 percent of a plant's cell walls but is often burned for process heat because it is difficult to depolymerize and upgrade into useful fuels or chemicals, NREL said.

Yet biorefineries that convert cellulosic biomass into liquid transportation fuels typically generate more lignin than they need for power, noted Gregg Beckham, senior engineer at NREL and a co-author of the study.

"Strategies that incorporate new approaches to transform the leftover lignin to more diverse and valuable products are desperately needed," Beckham added.

The new study – "Lignin Valorization Through Integrated Biological Funneling and Chemical Catalysis" – has been published in the Proceedings of the National Academy of Sciences. It shows that developing biological conversion processes for a lignin-utilizing organism may enable new routes to overcome the heterogeneity of lignin, leading to a broader slate of molecules derived from lignocellulosic biomass.

Researchers from NREL also participated in a recent review of lignin valorization published in Science magazine, which highlighted the potential for manufacturing value-added products from lignin. Such products could include low-cost carbon fiber, engineering plastics and thermoplastic elastomers, polymeric foams and membranes, as well as various fuels and chemicals that are currently sourced from petroleum.