One Molecule Could Cure Our Addiction to Oil

Trace the fortunes of cellulosic ethanol over the past three decades and you’ll find that the arc almost perfectly mirrors Lee Lynd’s career. The 49-year-old Dartmouth professor started in a compost heap in the 1970s, seemed on the verge of a breakthrough in the ’80s, and nearly went bust in the ’90s. “There were times,” he says, “when my lab barely had a pulse.” Now, as a central player in the burgeoning cellulosic industry, he works out of a rejuvenated Dartmouth lab and sparkling new offices in nearby Lebanon, New Hampshire, freshly equipped and staffed by nearly two dozen PhDs.

For Lynd, the key to the future lies in combining the two main stages of the cellulosic conversion pathway into a single process inside a single microbe.
Instead of using enzymes to make sugar out of plant material and then using yeast to convert that sugar to ethanol, Lynd is trying to create a bacterium that serves as an all-in-one fuel factory, taking up cellulose and spitting out ethanol. Called consolidated bioprocessing, or CBP, this has been his dream for two decades. “Almost everybody believes it’s doable,” he says. “People disagree whether it’ll take two years or 20.”

To get there, he needs to engineer cellulase production into a sugar-fermenting microbe like yeast or modify a cellulase-producing organism to make it ferment sugar. With plenty of research money in hand, he’s trying to do both. To accomplish the latter, Lynd and his colleagues are working with a cellulase-producing bacterium called Clostridium thermocellum. “You can isolate this puppy out of garden soil, hot springs, compost heaps, forest floors,” Lynd says. In 2005, the researchers proved that a bug very similar to C. thermocellum could be modified to make ethanol. Their goal is now to modify C. thermocellum to do the same. If he succeeds, Lynd’s analysis shows that CBP — by reducing the raw materials and capital required — could cut overall processing costs twofold, potentially the difference between a profitable ethanol plant and a money pit.

Meanwhile, Mascoma is pushing ahead to build factories that will use commercial cellulase enzymes until the superbug is available. That may not happen immediately, but Lynd is patient, having sought a breakthrough for three decades. “I’m not sure if that makes me inspired or an idiot,” he says. “Probably a little of both.”

Skeptics argue that rosy projections for cellulosic ethanol ignore its drawbacks — mainly, that cars need to be converted to run on it, that existing oil pipelines can’t transport it, and that we don’t have the land to grow enough of it. Advocates counter that if the fuel is cheap and plentiful enough, the infrastructure will follow. “If we could make ethanol at a large scale in a way that is sustainable, carbon-neutral, and cost-effective, we would surely be doing so,” Lynd says, citing the fact that most cars can easily be converted to run on ethanol, something already done with most new cars in Brazil. “Meeting these objectives is not limited by the fuel properties of ethanol but rather by the current difficulty of converting cellulosic biomass to sugars.”

Neither government funding nor venture capital, of course, guarantees research breakthroughs or commercial blockbusters. And even ardent proponents concede that cellulosic ethanol won’t solve our fuel problems — or do much to stop global warming — without parallel efforts to improve vehicle efficiency. They also worry that attention could again fade if the first demonstration plants fail or oil prices plummet. “To get this industry going, you need some short-term breakthroughs, by which I mean the next five to seven years,” says Martin Keller, a micro biologist at Oak Ridge National Laboratory in Tennessee and director of its new BioEnergy Science Center. “Otherwise, my fear is that people may leave this field again.”

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