Researchers have demonstrated a one-vat processing system in which sugars could be extracted from biomass and turned into fuels in a single vat, using less water and producing less waste, which would lower biofuel costs.
Scientists with the Energy Department’s Joint BioEnergy Institute (JBEI) developed a one-pot, wash-free process for the ionic liquid pretreatment and saccharification of switchgrass, one of the leading potential biofuel feedstocks. Combining pretreatment and saccharification into one step will allow for much less water usage and waste creation since the ionic liquid can be recycled and the sugar recovery process simplified. This will drive down production costs, scientists say.
The JBEI scientists describe their efforts to develop cost-effective ways to deconstruct cellulosic biomass into fuel sugars in a paper published in the July issue of Green Chemistry.
For biofuels to be cost-competitive with fossil fuels, it has to be economical to extract fermentable sugars from cellulosic biomass and synthesize them into fuels as well as other valuable by-products. JBEI researchers focused on pretreating biomass in switchgrass with ionic liquids — environmentally friendly organic molten salts often used as green chemistry substitutes — that are very effective in breaking down cellulosic biomass into fermentable sugars.
But the catch with using the liquid salts for pretreating is that they can inhibit the enyzme cocktails used for the saccharification process. This means they must be removed after pretreatment using massive amounts of water, which drives up the recycling and waste-disposal costs. To circumvent this washing process, JBEI researchers developed bacteria from compost that they grew on switchgrass, which can tolerate the presence of the salts and still extract the sugars from the biomass.
The next step for the researchers is to scale up this process.
Switchgrass is also being used in research focused on producing plant-based polymers to manufacture plastic. Companies like Metabolix are exploring whether plants can be genetically engineered to make polymers for producing bioplastics in a way that’s cheaper than oil-based plastics.
Image credit: Roy Kaltschmidt, Lawrence Berkeley Lab