EMERYVILLE, Calif. -- In a slick, glass-clad office building just blocks from the San Francisco Bay, researchers are running what amounts to a high-tech craft brewery. But instead of making exotic beers, they are cooking up what they hope will become America's top biofuel, one made from wastes that can dethrone the current champion, corn-based ethanol.
Though it stemmed from good intentions, ethanol, the process that makes it and the policies around it are showing their seams and wrinkles.
Environmental advocates are concerned the current crop of biofuels isn't as green as it's cracked up to be, and policymakers are worried they're on a crash course with the blend wall -- the imbalance between the maximum amount of ethanol gasoline engines can tolerate and the amount required under the renewable fuels standard.
Here at the Department of Energy's Joint BioEnergy Institute (JBEI), scientists are hunting for a biofuel that fixes ethanol's flaws by pooling resources from four national laboratories and three educational institutions.
The facility, dedicated in 2008 -- and as yet unaffected by the government shutdown -- will receive $25 million per year through 2017. It is one of three bioenergy research centers established by DOE's Office of Science.
The logic behind the research is that plants and some other organisms soak up carbon dioxide from the sky as they grow, so burning them later has no net impact on greenhouse gases in the atmosphere. Thus, burning biofuels will chip away at the 9 billion metric tons of excess carbon dioxide spewing into the atmosphere from fossil fuels each year. This is an appealing alternative to dredging up the buried remains of dinosaur-age jungles to power engines and jet turbines that add their emissions to the atmosphere.
"At JBEI, we have several mantras that govern our existence, and one of them is 'Ethanol is for drinking, not for driving,'" said Blake Simmons, vice president of the deconstruction division at JBEI. Deconstruction, Simmons explained, is the process of breaking down plants into their constituent parts before reassembling them into improved biofuels.
Moving away from food-based materials
Lignocellulosic biomass, the tough cells that give plants their structure, is the most abundant organic material on Earth. It is an especially attractive feedstock to tear apart. Generally, this is the inedible part of plants and includes wastes from food crops as well as hardy grasses that grow in low-quality land. It solves the food security issue caused by turning grain into fuel, and potentially it could be cheap, because the United States produces more than a billion tons of this biomass annually.
But the energy-producing sugars in lignocellulosic biomass are harder to extract than they are from corn kernels, and the economics and the technology haven't converged yet to make these biofuels competitive.
"There are a couple big, 800-pound gorillas that lignocellulosic biofuels have to tame in order to be cost-effective," Simmons said.
The first gorilla is the cost of the enzymes that break down the lignocellulose into individual sugars to be fermented or processed. The enzymes can tack on an extra 50 cents to $1 to each gallon of biofuel.
"The feedstock cost is another big determinant, and the pretreatment cost is another big determinant," he added. "There's a lot of moving parts when people talk about cost competitiveness with oil and gas."
However, the existing methods to draw biofuels from lignocellulose are inadequate. "Most of the deployed state of the art is from the pulp and paper industry," Simmons said.
Rather than repurposing existing systems, researchers at JBEI are striving to come up with new ways to make diesel, jet fuel and gasoline substitutes from plants.
One approach is to replace conventional acid treatments to break down the biomass with "ionic liquids," which are essentially salts that melt below room temperature. When added to lignocellulose, these liquids dissolve the crystal structure of this polymer and make it more accessible to enzymes. This streamlines the process and cuts down the amount of enzymes needed.
'One pot' system
Using ionic liquids, JBEI researchers recently demonstrated a method to combine pretreatment and conditioning for biomass in what they describe as a one-pot, wash-free process. This simplifies biomass processing, thereby cutting production expenses.
The one-pot system also works at a lower temperature system than commercial biomass pretreatments, so it reduces energy costs. "In a one-pot process, just by adding water or ionic liquids, you bring down the temperature to room temperature, so there's no need for an extra system to cool it down," said Jian Shi, a postdoctoral process engineer at JBEI. He explained that the processing liquids are recyclable, cutting some of the additional expenses from using ionic liquids.
In the feedstocks, researchers are delicately balancing genetic tweaks that can improve fuel yields without compromising a plant's ability to grow and survive. Dominique Loque, director of cell wall engineering at JBEI's feedstocks division, explained that researchers first test modifications in model plants that have a fast turnover like tobacco and Arabidopsis.
"If you move to crops directly, it takes forever," Loque said.
Researchers are also keeping an eye on other ways to enhance sustainability in biofuels. "If you can improve the plant to need less fertilizer, then you will have less CO2 emissions," Loque said, noting that producing and applying nitrogen fertilizers requires a tremendous amount of energy.
After coming up with a working biofuel formula, JBEI scientists then test how well it can scale up. Julio Baez, the program manager for the Advanced Biofuels Process Demonstration Unit, explained that his mission is to iron out kinks in taking lab experiments to industrial proportions.
How to compete with natural gas?
But before a new biofuel system gets ramped up, Baez said, researchers first have to analyze it for technical feasibility as well as economic viability. "The third thing we do is a life-cycle analysis, or you could call it sustainability or you could call it a carbon footprint," he said. "It's the concept that we'll figure out if this process is going to actually help the environment, which is what we want."
Once it clears this threshold, researchers then produce a given biofuel formula at scale in bioreactors up to 300 liters in size and transfer the results to stakeholders.
"We need to understand that what we do here has to be done at thousands of liters," Baez said, observing that once engineers can make fuels at the scale of hundreds of liters, they have most of the understanding required to construct a much larger facility. (A liter is 0.264 gallon.) "This [demonstration] scale is the scale that you need to build a 300,000-liter plant."
However, in terms of competitiveness, biofuel scientists are trying to hit a moving target. Baez noted the surge in natural gas production in the United States changed the landscape for biofuels, dissolving the energy security argument and forcing researchers to concentrate more on cost competitiveness.
Simmons is optimistic nonetheless and said research is helping scientists and policymakers figure out the appropriate niches for given biofuels and other energy strategies, rather than picking winners and losers. "We're getting to the point where we have those tools to make the right decisions," he said.