Science for our
Nation's
Energy Future

Energy Frontier Research Center

Community Website
Frontiers in
Energy Research
Newsletter
September 2011

Reusing Carbon for Green Gasoline and Biopower

Engineers discover the basic reactions which utilize CO2 for advanced biofuels

Paul J. Dauenhauer

Biofuels processes have a simple objective: reuse waste carbon dioxide, aka CO2, by converting it to biofuels as efficiently and economically as possible. However, this seemingly simple task requires sequential chemical steps that must be independently improved and collectively optimized. Research centers throughout the United States are tackling biomass production, thermal conversion, and catalytic upgrading to create the next generation of biofuels.

The CO2 reuse process: Multiple research centers currently focus on one of four key steps in the CO2 reuse process for biofuels production. Biomass growth by photosynthesis converts CO2 to lignocellulosic (non-food) biomass such as trees, algae and grasses. These materials are converted by thermal processing to an intermediate liquid, called “bio-crude.” Subsequent catalytic upgrading produces biofuels in high yield. Finally, the biofuels are converted back to atmospheric CO2 by fuel cells, combustion engines or other technologies. All four of these areas are being rapidly advanced with discoveries by Energy Frontier Research Centers.

Biomass growth: Using sunlight, atmospheric CO2 is captured by photosynthesis to produce sugars. Subsequent reaction of the sugars produces cellulose, which is a key building block for lignocellulose, the main structural component of plants.

The Center for Lignocellulose Structure and Formation, CLSF, reveals a key detail in the production of cellulose. The biological machinery to produce cellulose consists of many proteins which work together. The CLSF team has identified the location of a key protein, referred to as “AcsD.” This discovery is a significant advance for understanding how biomass materials are constructed and will aid in the engineering of more efficient biomass crops.

Thermal conversion of biomass: Once constructed by nature, biomass must be thermally deconstructed so that it can be integrated into a biorefinery. One leading technology involves the rapid heating of biomass to produce bio-crude, which can be processed similar to crude petroleum. Understanding the chemical process by which the bio-crude forms is an interest of the Center for Direct Catalytic Conversion of Biomass to Biofuels, C3Bio.

Members from C3Bio have discovered the very first reactions of cellulose when it is heated to 440 °F. Cellulose polymers naturally form fibers in biomass materials such as wood. Using a molecular computer simulation, the researchers show that long cellulose fibers interact differently when heated and can twist and untwist. This detail reveals the structure of biomass as it reacts and leads to a better understanding of bio-crude production.

Catalytic upgrading and utilization of biomass: Biomass-derived feedstocks such as bio-crude must be catalytically upgraded in a biorefinery to produce green gasoline, renewable diesel or electrical power. These fuels are produced primarily using inorganic catalysts which remove oxygen from bio-crude to produce liquids nearly identical to conventional petroleum-based fuels. The development of new catalyst technologies and inorganic processes necessary to produce biofuels is the primary goal of the Catalysis Center for Energy Innovation, CCEI.

In the past year, members of the CCEI have demonstrated an entirely new process to utilize biomass carbon for electrical energy with a fuel cell. In their process, a fuel cell produces power by reacting air with antimony, which serves as an energy carrier. The antimony is recovered while carbon from the bio-crude is converted to CO2 and emitted into the atmosphere. This process operates continuously and could achieve electrical efficiencies significantly greater than existing technologies.

These discoveries demonstrate the potential of reusing CO2 as a carbon source for biofuels. By picking apart this complex problem, Energy Frontier Research Centers are collectively solving the biofuel and CO2 challenge.

More Information

Iyer PR, J Catchmark, NR Brown, and M Tien. 2011. “Biochemical Localization of a Protein Involved in Synthesis of Gluconacetobacter hansenii Cellulose.” Cellulose 18, 739-747. DOI: 10.1007/s10570-011-9504-4. 

Matthews JF, M Bergenstrahle, GT Beckham, ME Himmel, MR Nimlos, JW Brady, and MF Crowley. 2011. “High-temperature Behavior of Cellulose I.” Journal of Physical Chemistry B 115, 2155-2166.DOI: 10.1021/jp1106839

Jayakumar A, R Kungas, S Roy, A Javadekar, DJ Buttrey, JM Vohs, and RJ Gorte. 2011. “A Direct Carbon Fuel Cell with a Molten Antimony Anode.” Energy and Environmental Science. Advance Article. DOI: 10.1039/C1EE01863A

Acknowledgments

This work was supported as part of the Catalysis Center for Energy Innovation, the Center for Direct Catalytic Conversion of Biomass to Biofuels and the Center for Lignocellulose Structure and Formation, which are Energy Frontier Research Centers funded by the U.S. Department of Energy, Office of Basic Energy Sciences.

About the author(s):

  • Paul J. Dauenhauer, Ph.D., is a member of the Catalysis Center for Energy Innovation and Assistant Professor of Chemical Engineering at the University of Massachusetts, Amherst. He received his Ph.D. from the University of Minnesota in 2008 and has worked for both the Dow Chemical Company and Cargill, Inc.

More Information

Iyer PR, J Catchmark, NR Brown, and M Tien. 2011. “Biochemical Localization of a Protein Involved in Synthesis of Gluconacetobacter hansenii Cellulose.” Cellulose 18, 739-747. DOI: 10.1007/s10570-011-9504-4. 

Matthews JF, M Bergenstrahle, GT Beckham, ME Himmel, MR Nimlos, JW Brady, and MF Crowley. 2011. “High-temperature Behavior of Cellulose I.” Journal of Physical Chemistry B 115, 2155-2166.DOI: 10.1021/jp1106839

Jayakumar A, R Kungas, S Roy, A Javadekar, DJ Buttrey, JM Vohs, and RJ Gorte. 2011. “A Direct Carbon Fuel Cell with a Molten Antimony Anode.” Energy and Environmental Science. Advance Article. DOI: 10.1039/C1EE01863A

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.