Biofuels: The Next Generation

As corn-based ethanol hits roadblocks, all eyes are turning to advanced biofuels. These, too, face difficult challenges, but that's not stopping a host of startups

THE FEEDSTOCKS (mainly cellulose-rich material, but also algae)

MUNICIPAL OR AGRICULTURAL WASTEPros: Cheap for nowCons: Supply too limited to make billions of gallonsThe Players: BlueFire Ethanol (trash); POET (corncobs); Verenium (sugarcane residue)

WOODPros: Adequate supply in Southeast and other parts of the U.S.; easy to harvestCons: It's harder to extract cellulose from wood than from other feedstocksThe Players: Range Fuels, Coskata

ALGAEPros: Potential for high yields per acreCons: Scale-up is challenging; typically requires source of CO2 to bubble through algaeThe Players: Algenol, Sapphire Energy, HR BioPetroleum, Solix, PetroAlgae

SWITCHGRASS, MISCANTHUS, AND OTHER SPECIALIZED ENERGY CROPSPros: Potentially vast supply; can improve soils; small carbon footprintCons: Challenges in establishing, harvesting, and delivering to biorefineryThe Players: DuPont Danisco (switchgrass); Verenium ("energy" cane); Iogen (wheat straw)


ETHANOLPros: Can sell it into existing marketCons: Limits on how much can be added into gasoline nowThe Players: POET, Range, Mascoma, Verenium, Algenol, DuPont Danisco, Coskata, Qteros, others

BUTANOL AND OTHER MORE GASOLINE-LIKE PRODUCTSPros: Can be added to gasoline in large amounts and used in existing pipelinesCons: Greater technological challenges; higher costs than ethanolThe Players: DuPont, BP, Gevo, Virent, Amyris

BIODIESEL AND JET FUELPros: Works with existing infrastructureCons: May be difficult to produce economicallyThe Players: PetroAlgae, Solazyme (from algae); Amyris, LS9, Gevo, OPX (from any sugar)

THE PROCESSES (converting feedstock to fuel)

HEAT, CHEMICALS, OR MINERAL CATALYSTSPros: Potential to use wide range of feedstocks; catalysts can produce variety of fuelsCons: May take more energy than biological processes and may require additional purification stepsThe Players: Range Fuels, Coskata (heat feedstock to make gas); BlueFire Ethanol (strong acid, microbial fermentation); Virent (catalysts)

BIOLOGICAL (ENZYMES AND/OR MICROBES)Pros: Depending on feedstock, the process is very energy-efficientCons: Has to be adjusted for each type of feedstock; enzymes are still costlyThe Players: Solazyme (algae); Mascoma, Qteros (one-step microbes); Iogen, DuPont Danisco, Verenium (enzymes, microbes)

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