Biofuels blend right in

January 30, 2013

Winemakers have long known that blending different grape varietals can favorably balance the flavor characteristics of the wine they produce. In the future, makers of advanced biofuels might use a similar strategy, blending different feedstock varieties to balance the energy characteristics of the transportation fuel they produce.

A collaborative study by researchers with the U.S. Department of Energy (DOE)'s Joint BioEnergy Institute (JBEI), a bioenergy research center led by Berkeley Lab, and the Idaho National Laboratory (INL) has shown that an ionic liquid proven to be effective for pre-treating individual biofuel feedstocks is also effective at pre-treating multiple different feedstocks that have been mixed and densified into a blend.

"Our results show that an ionic liquid pre-treatment can efficiently handle mixed feedstocks that have been milled and densified into pellets, and can generate high yields of fermentable sugars regardless of upstream processing," says Blake Simmons, a chemical engineer who heads JBEI's Deconstruction Division. "This indicates that blending and densifying a wide range of feedstocks has significant potential for helping to make biofuels a cost-competitive transportation fuel technology."

Simmons and his JBEI colleague Seema Singh, director of JBEI's Biomass Pretreatment group, led the JBEI/INL study in which four biomass feedstocks, representing the general classes of plants well-suited to serving as fuel crops, were mixed and milled into either flour or pellets then pre-treated with 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), the ionic liquid used at JBEI as a benchmark for biomass processing. The objective was to determine the impact of mixing and densification on the efficiency at which the complex polysaccharides in cellulosic biomass could be converted into fermentable sugars for fuel production.

"Lignocellulosic biorefineries must be able to efficiently process available regional feedstocks at cost-competitive prices year round, but feedstocks markedly vary from region-to-region," Singh says. "Also, individual feedstocks within a given region are also quite variable, depending on weather conditions, handling, storage and crop variety. Blending and densifying different feedstocks to create a single uniform feedstock has been proposed as a solution, but not much scientific attention has been paid to the efficiency of converting mixtures of feedstocks into fermentable sugars and fuels."

Given that global temperatures are now setting record highs and that the burning of fossil fuels is releasing an additional 9 billion metric tons of excess atmosphere-warming carbon each year, both the planet and the American economy stand to benefit from a large-scale domestic advanced biofuels industry. Produced from the microbial fermentation of sugars in lignocellulosic biomass, advanced biofuels are clean, green and renewable, and could displace gasoline, diesel and jet fuel on a gallon-for-gallon basis and be directly dropped into today's engines and infrastructures.

The sugars in lignocellulosic biomass, however, are complex polysaccharides that are deeply embedded within a very recalcitrant material called lignin. To break apart the complex lignocellulose and help hydrolyze the released polysaccharides into sugars that can be fermented by microbes, researchers at JBEI and elsewhere have been studying biomass pretreatments with ionic liquids - environmentally benign organic salts often used as green chemistry substitutes for volatile organic solvents.

Researchers at INL have been investigating ways to increase the energy densities of biomass feedstocks and make delivery to refineries much more economical. Milling feedstocks into flour or pellets is an effective process for large-scale energy densification, but before this latest study it was unknown as to how densification of single or mixed feedstocks would impact ionic liquid pretreatment and sugar yield.

The JBEI/INL collaboration mixed switchgrass, lodgepole pine, corn stover and eucalyptus in flour and pellets and within 24 hours of saccharification were able to obtain sugar yields of up to 90-percent for both forms. Pellets, because of their higher energy density, would be the preferred form.

"Our work is the first demonstration that ionic liquid pretreatments can effectively handle mixed and densified feedstocks," Simmons says. "We're continuing the collaboration to next identify the most economical pelletized feedstock mixtures based on targeted regions of the United States. We'' then determine how efficiently our process can convert these mixtures into fermentable sugars."
The collaboration has published their results in the journal Biofuels in a paper titled "Impact of mixed feedstocks and feedstock densification on ionic liquid pretreatment efficiency." Co-authors, in addition to Simmons and Singh, were JBEI's Jian Shi and Vitalie Stavila, and INL's Vicki Thompson and Neal Yancey.

JBEI is one of three Bioenergy Research Centers established by the DOE's Office of Science in 2007. It is a scientific partnership led by Berkeley Lab and includes the Sandia National Laboratories, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science, and the Lawrence Livermore National Laboratory. DOE's Bioenergy Research Centers support multidisciplinary, multi-institutional research teams pursuing the fundamental scientific breakthroughs needed to make production of cellulosic biofuels, or biofuels from nonfood plant fiber, cost-effective on a national scale.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the Unites States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at

DOE/Lawrence Berkeley National Laboratory

Related Ionic Liquids Articles from Brightsurf:

A new candidate material for quantum spin liquids
Using a unique material, EPFL scientists have been able to design and study an unusual state of matter, the Quantum Spin Liquid.

Porous liquids allow for efficient gas separation
Jointly with partners, a researcher of Karlsruhe Institute of Technology has developed 'porous liquids': Nanoparticles, that are able to separate gas molecules of different sizes from each other, float - finely distributed - in a solvent.

Space invaders as MOFs act as liquids
Modified metal organic frameworks that can behave as porous liquids offer new possibilities for gas separation technologies.

The nature of glass-forming liquids is more clear
Researchers from The University of Tokyo have found that attractive and repulsive interactions between particles are both essential to form structural order that controls the dynamics of glass-forming liquids.

Optical 'nanomixer': Scientists propose new method for mixing liquids
Every now and then, scientists need to control the process of mixing liquids in vessels so small that the thinnest needle or even a hair wouldn't fit in there.

New route of assembly and ionic channel traffic in cardiac cells
Ionic channels -integral proteins in the cell membrane- are essential in several processes such as cardiac activity, nervous transmission, cell proliferation and the regulation of blood pressure.

Cases of poisoning: Liquids containing cannabidiols for e-cigarettes can be manipulated
The health risks of e-cigarettes have come into focus after the deaths of several 'vapers' due to lung injury in the USA recently.

Can ionic liquids transform chemistry?
Table salt is a commonplace ingredient in the kitchen, but a different kind of salt is at the forefront of chemistry innovation.

Physicists prove that 2D and 3D liquids are fundamentally different
A 50-year-old puzzle in statistical mechanics has been solved by an international team of researchers who have proved that two-dimensional (2D) liquids have fundamentally different dynamical properties to three-dimensional (3D) liquids.

Fast ionic transport interphase for stable Mg metal anodes in conventional electrolyte
Researchers report a simple, safe and effectively method to resolve the irreversibly plating/stripping problem in Mg(TFSI)2/DME electrolyte.

Read More: Ionic Liquids News and Ionic Liquids Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to