Australians develop glycerol-based biomass pretreatment process

Australia-based Leaf Energy Ltd. is developing a new biomass pretreatment process that utilizes glycerol, a coproduct of the biodiesel process, in a Glycerol Bio-refinery Process, which the company says uses lower temperatures and pressures, requires less enzymes and releases fewer inhibitors than other pretreatment systems in development.

“Data published in the patent specification for the ‘Glycerol Bio-refinery Process’ shows that after 24 hours, this process can liberate over 90 percent of the digestible cellulose,” said Alex Baker, chief operating officer. “We believe this is a significant improvement over the current acid/steam processes.” Not only does the process use temperatures of 130 degrees Celsius, considerably lower than steam explosion or dilute acid systems, but the company also says it is a quicker process that does not degrade the lignin coproduct.

Using glycerol as a pretreatment has some distinct advantages, being a biodegradable and recyclable waste product from the biodiesel process, pointed out managing director Ken Richards in a presentation at the company’s Nov. 22 annual meeting. Leaf Energy projects that by 2020, glycerol production will exceed demand six-fold, and thus remain a low-cost ingredient.

The pretreatment process was developed at Queensland University of Technology by Zhanging Zhang, Ian O’Hara and William Doherty. The patent applications for the Glycerol Bio-refinery Process are part of the joint intellectual property (IP) developed under the collaboration and license agreement between Leaf Energy, Syngenta, QUT and QUTBluebox. Leaf Energy has rights to these patents in Australasia and is in the process of obtaining rights to the IP in India, Thailand, the Philippines, Nicaragua, Guatemala, Mauritius, Malaysia and Indonesia.

The glycerol pretreatment has been successfully tested using sugarcane bagasse, and will work on other biomass substrates, the company said. The next step for Leaf Energy is pilot-scale testing of the entire process using bagasse, the proprietary pretreatment technology, plus fermentation into cellulosic ethanol. The company expects the pilot testing to begin later in 2013, according to Baker, which he added will be the first significant demonstration of second-generation biofuel in Australia. 

Leaf Energy is also collaborating with Texas A&M University on Debaryomyces hansenii, a high oil-producing marine yeast, with laboratory work currently focused on elite strain selection. “Our work with D hansenii has been evaluating its potential in the biofuels space,” Baker said. “In particular, [evaluating] the organism’s ability to utilize its oil pathways to deal with glycerol and pentose side streams from cellulosic ethanol proposed in the glycerol biorefinery process and other systems.”

 Leaf Energy has rights to another technology developed by QUT researchers, INPACT, for the activation and amplification of transgene expression. The technology can be used to increase the expression and yield of novel proteins, enzymes and other molecules of commercial interest in desirable plants. The company reported in its preliminary year-end report to the Australian Stock Exchange that, in addition to the pretreatment process, the collaborative effort is working on “self-processing” sugarcane varieties that express cellulases.

Publicly traded Leaf Energy Leaf Energy was formed in mid-2010 with the merger of two companies, Farmacule Bio-industries and AquaCarotene Ltd. Farmacule was a spinoff from QUT research, and mainly focused on plant genetic technologies. AquaCarotene was a micro-algae development company. The algae technology assets were sold to Aurora Algae following the merger.