The beauty of the endophytic fungi, Sandia biochemist Masood Hadi said, is that there is no need for the cost-intensive industrial processes that are typically required to break down biomass. “These things can turn crystalline cellulosic material directly into fuel-type hydrocarbons without any mechanical breakdown,” he said.

The fungi grow on cellulose and digest it, forming fuel-type hydrocarbons as a by-product of their metabolic processes. Through genetic manipulation, the Sandia team hopes first to identify these pathways, and then to improve the yield and tailor the molecular structure of the hydrocarbons it produces.

Sandia’s bioscience team is using genetic sequencing to catalog the pathways and other molecular biology techniques to understand how changes in feedstock determine the type and amount of hydrocarbons the fungi make, with a long-term goal of engineering greater quantities of the desirable fuel species.

Meanwhile, Craig Taatjes and John Dec, both engine combustion researchers at Sandia, are experimenting with the main compounds produced by the fungi and are giving feedback to their bioresearch counterparts on the compounds’ ignition chemistry and engine performance. The ideal outcome, Dec said, is to “dial in” the right feedstocks combined with the right set of genes to produce the preferred blend of compounds to go into an engine.

The first step has been to learn what kinds of compounds the fungus makes naturally on its own. “We just don’t know much about some of the compounds, so we need to do research on their ignition chemistry and how they behave in an engine,” Taatjes said. The team, he says, is working with Professor William H. Green at the Massachusetts Institute of Technology to develop an ignition chemistry model that can predict the performance of the classes of compounds made by the fungus.

Hadi and his colleagues are contributing to building up the understanding of the distribution of molecules produced by the various fungi, at which point they can genetically tailor them to produce more of the optimal compounds to suit the needs of engine combustion.

Eventually, the team anticipates that enough hydrocarbons will be extracted from those produced by the fungus to test in the lab, or even in an engine. “We hope, in the end, to have a biofuel that was developed in conjunction with the development of the combustion model for that biofuel,” Taatjes said.

Dec, who runs the Homogeneous-Charge Compression Ignition (HCCI) lab at Sandia, said experiments on the HCCI platform offer good fundamental information on fuel auto-ignition behavior that can be related to performance in other engine types, such as spark-ignition or diesel, as well as to performance in HCCI engines.

Taatjes, Dec and Hadi all agree that it makes perfect sense for Sandia to invest in a project that focuses on an engine’s interaction with a new biofuel. Another aspect of this project, Taatjes said, is that the biofuels researchers are working directly with the combustion experts to understand from the start just what will work best as fuel for internal combustion engines, accelerating the pace of alternative fuel development and the associated engine optimization.

There is a whole new range of potential fuels now with biomass. The new fuels will have to work well with both existing engines and advanced engines, like HCCI or low-temperature diesel combustion. Only then will you be able to sell the fuel at the pump and get your new high-efficiency, low-emissions engine into the marketplace.

—John Dec

Resources

• Angela R. Tomsheck, Gary A. Strobel, Eric Booth, Brad Geary, Dan Spakowicz, Berk Knighton, Cody Floerchinger, Joe Sears, Orna Liarzi and David Ezra (2010) Hypoxylon sp., an Endophyte of Persea indica, Producing 1,8-Cineole and Other Bioactive Volatiles with Fuel Potential Microbial Ecology Volume 60, Number 4, 903-914, doi: 10.1007/s00248-010-9759-6

• Meghan A Griffin, Daniel J Spakowicz, Tara A Gianoulis and Scott A Strobel (2010) Volatile organic compound production by organisms in the Ascocoryne genus and a reevaluation of myco-diesel production by NRRL 50072 Microbiology doi: 10.1099/mic.0.041327-0