The October 15 issue of Wired magazine contains an informative article about cellulosic ethanol. Titled “One molecule could cure our addiction to oil,” the article, by Evan Ratlif, is cautiously bullish on cellulose, concluding that the proliferation of well-funded research efforts “stacks the deck in favor” of cellulosic ethanol becoming cost-competitive in five to seven years.

Well, only time will tell. As Ratlif notes, the federal government first funded research on cellulosic ethanol in the ’70s. And although, “We can run our cars on lawn cuttings today; we just can’t do it at a price people are willing to pay.”

However, what makes this article valuable is not the author’s hunches, to which he is certainly entitled, but its lucid overview of the chemistry and economics of cellulosic ethanol and profiles of three leading players in the field. Here are a few tidbits:

• The ethanol we can make today-from corn kernels-is a mediocre fuel source. It generates at best 30 pecent more energy than is required to grow and process the corn-hardly worth the trouble. Plus, the crop’s fertilizer-intensive cultivation pollutes waterways, and increased demand drives up food costs (corn prices doubled last year). And anyway, the corn ethanol industry is projected to produce, at most, the quivalent of only 15 billion gallons of fuel by 2017.
• Cellulose is the most abundant naturally occurring organic molecule on the planet, a potentially limitless source of energy. However, cellulose is a “tough molecule” and no one yet has figured out how to turn it into ethanol at price competitive with gasoline.
• Turning cellulose into ethanol has three main steps: (1) Apply heat or chemicals to strip off cell-wall protections, (2) add enzymes called cellulases to break the cellulose down into sugars, and (3) add yeast or other micro-organisms to ferment the sugars into ethanol.
• Commercially, the make or break step is (2). “Today’s cellulases are the equivalent of vacuum tubes: clunky, slow, and expensive. Now, flush with cash, scientists and companies are racing to devlop the cellulosic transistor.”
• Scientists and entrepreneurs are pursuing three main strategies to build the “transistor”:
  • Bioengineer microbes that can both break down the cellulose and ferment the sugar–also known as “consolidated bioprocessing” (CBP), pioneered by Dartmouth Professor Lee Lynd, founder and CEO of Mascoma.
  • Mutate micro-organism genes to make cellulases that are more heat resistant and more efficient in degrading cellulose–the “directed evolution” approach pursued by companies such as Novozymes.
  • Look high and low (e.g. termite guts in Costa Rica) for better enzymes in the wild–the “collection” method favored by Venerium, an energy company.

In an interesting side bar, the article quotes Jay Keasling’s mantra: “Ethanol is for drinking, not driving.” Ethanol, whether derived from corn, cellulose, or sugarcane, produces only 85 percent of the energy of gasoline, requires retrofitting car engines, and is incompatible with existing oil pipelines. That’s why Keasling, a chemical engineer at UC Berkeley and Lawarence Berkeley National Laboratory in California, is trying to create microbes that can turn cellulosic biomass, not into ethanol but into a fuel molecularly similar to gasoline.