Shijie Liu, Associate Professor and Associate Director at Biorefinery Research Institute, Department of Paper and Bioprocess Engineering at SUNY College of Environmental Science & Forestry (ESF) in Syracuse NY, provided his insights on the conversion of woody biomass to chemicals, energy and materials.

He began his talk with a vision - “Imagine a renewable world” - and explained that biofuel is truly renewable because to produce it you don’t have to have fossil fuel. Then he went on to show how.

Woody biomass components are where the action is. Wood contains lignin (hardwoods contain 35 percent lignin, softwoods 25 percent); carbohydrates, mainly hemicellulose (hardwoods 35 percent, softwoods 25 percent); cellulose at 45 percent; and 2.8 percent extractives which include inorganics.

The incremental deconstruction of woody biomass to harvest all of its useable components, said Liu, will maximize value achievable, minimize energy loss and waste products, provide a multiple product mix and eliminate the pre-treatment process for some products.

His model is an integrated biorefinery like the ESF biorefinery used in his research which utilizes several processes. The first of these is hot water extraction.( The ESF recipe starts with a 65 cu. ft.  digester reactor, adds 500-800 lbs wood chips, and heats at 160 C for 2 hours to produce the liquor.) Another process is hydrolysis  (100 g wood chips at 160 C for 2 hrs with water to solids at 4:1). Fractionation using a nano-filtration membrane system in 65 cu. ft. tanks with a membrane unit for separation is another process Liu’s research is looking at. Fermentation to ethanol, plastics, etc. follows. 

The uses for residual woody biomass include pulping  (for paper and fiber products); fiberboard and other reconstructed wood products; wood fuel such as pellets; biomass energy such as combined heat and power (CHP); hydrolysis to convert cellulose to platform chemicals; and lignin for chemicals and energy.

Liu’s research has found that the biorefining process will improve the solid material by removing ash, acetyl and carbonyl, and hemicellulose, with no strength change. It also provides a lighter mass which is potentially less hygroscopic.

The solid material used for wood composites is fiberized, lighter, less hygroscopic, has the potential to be moisture insensitive and extend the life of the product.

When used for wood pellets, the solid material requires no grinding and has low ash content.

The species used in Liu’s research were aspen, mixed northern hardwoods, mixed southern hardwoods, eucalyptus and willow. Liu noted that each species required a slightly different process.