UC Berkeley: Why Switchgrass Matters, and Algae by the Numbers

It's field trip day, and I'm at the Synthetic Biology Workshop at the University of California Berkeley co-sponsored by Innovation Center Denmark.

And naturally, one of the main topics is cellulosic ethanol, particularly from wild grasses like switchgrass and miscanthus.

"They can grow without fertilizer with little water on somewhat marginal land," said Henrik Scheller, director of cell wall biosynthesis at the Joint BioEnergy Institute at Berkeley.

The price is right too. Switchgrass and miscanthus can be grown for $50 to $80 a ton. That translates to feedstocks for ethanol of around 49 to 78 cents a gallon and feedstocks for octane (gas) producers at 72 cents to $1.15. By contrast, corn starch as an ethanol feedstock at the moment costs around $1.90. Using corn for octane would come to $2.80 a gallon. Palm oil is now around $2.55 a gallon and sucrose, the sugar harvested from Brazilian sugarcane, comes to around $2.15 a pound. Although sugar and corn prices are still above their traditional norms, these traditional feedstocks would still cost more than the grasses.

Unfortunately, lignocellulose is the most difficult to convert into sugars that can then be turned into alcohols or other substances. "The difficulty is in the processing," he said.

Research in the next few years will focus on ways to make it easier to remove lignin, the tough protein that surrounds plants. Research will also continue on enzymes to remove deconstruct plant materials, but progress could be more incremental. Enzymes are already highly evolved. Industrial enzymes come largely from a species of enzyme called Trichoderma, which in its natural state can chew up tents in the Philippines.

Another big focus for research: phase separation. Now, alcohol is distilled to separate it from water, a time consuming process. If microbes could be developed that produce fuels that will naturally separate from water somewhat quickly, the energy required to make fuel could be greatly reduced.

Algae? He likes it. But it may not be a miracle cure. Algae is capable of capturing 10 watts of energy per square meter, which translates to 4,385 gallons of fuel per acre per year. Although some companies promise 50,000 gallons of algae an acre, unless they shine lights on it, it won't happen.

"We can't promise more out of algae than incident sunlight can provide," he said.

Fun fact: It takes eight photons of light for algae to capture a single molecule of carbon dioxide.

Biofuels invariably will require genetic engineering, but it is debatable whether protests will erupt in the U.S.

"I've always viewed GMOs as a European problem," he said. A while back, he had a Swiss delegation in his lab. When they asked if some of the plants were genetically modified, and learned that they were, the guests asked why there weren't any guards around the lab.