After a rash of negative publicity, biofuels backers say that advanced technologies will reshape the industry, making ethanol from sustainably grown sources cost-effective within a few years.
General Motors on Friday convened a panel of experts from cutting-edge ethanol companies that described different technologies--acid hydrolysis, specialty microbes, and genetically engineered energy crops--which they say will bring back biofuels' faded luster.
The key technology transition, already under way, is shifting from corn to other feedstocks for making ethanol from plant cellulose. With the right technologies and policies in place, the U.S. could meet one-third of its transportation fuel needs by 2030, said Candace Wheeler, a technical fellow at GM's research and development center.
The near-term projection is that, once ongoing plant construction is completed, ethanol will supply almost 10 percent of the U.S. gasoline demand, according to the Renewable Fuels Association. Nearly all of that will come from corn.
Wheeler said that the "low-hanging fruit" feedstock for cellulosic ethanol is wood chips and other agriculture wastes. But to get to one-third of demand, long-promised ethanol feedstocks such as fast-growing grasses need to enter the ethanol picture.
"To really get a significant impact...you are going to have to use purposely grown energy crops," she said. "It's really a timing issue. With improvements in technology and economics, these things will be real in the very near future."
After a period of government support and rapid investment, a biofuels backlash kicked into gear last year, with people questioning the environmental and economic benefits.
One concern is that farmland diverted to grow energy crops has contributed to higher food prices. Some U.S. senators, including John McCain, have called for repealing the existing biofuels mandates; European political leaders have also reconsidered its policies.
Also, corn ethanol emits roughly the same amount of greenhouse gases as gasoline, according to studies. Ethanol's impact on air quality is being studied by academics. GM has commissioned a study on this issue as well, Wheeler said.
Researchers say that cellulosic ethanol can lower greenhouse gas emissions significantly and that grasses, such as miscanthus and switchgrass, can be used to make ethanol on marginal crop lands.
However, cellulosic ethanol has yet to be produced on a commercial scale at competitive prices.
That will change once genetically optimized energy crops begin to be harvested, predicted Richard Hamilton, CEO of Ceres. The company uses genomics to analyze plant genes and breed grasses and fast-growing trees like poplar, willow, and eucalyptus.
"We need energy crops to get the industry to scale," Hamilton said during the conference call of panel speakers. "Within the next years, we are going to see competitive production costs. Cellulosic biofuels will be very cost-competitive with oil or other sources of biofuels."
Ceres' first sorghum and switchgrass seed products, sold under the Blade Bioenergy Crops brand, will be available this fall and planted next spring, he said. They are bred to be drought-resistant and grow rapidly.
Multiple technology paths
Right now, most ethanol production is going to the pumps in the form of a 10 percent blend with gasoline. Flex-fuel cars can run E85, a mix of 85 percent ethanol and gasoline, which is available at only about 1 percent of U.S. filling stations.
GM has committed to making half of its fleet flex-fuel capable by 2012. To prime the pump for E85, it has invested in two ethanol start-ups which are among the most favored to bring cellulosic ethanol to market.
Mascoma, spun out of Dartmouth College, is designing an ethanol-producing microbe that it says will lower the cost of ethanol production by cutting out the traditional step of using enzymes to make sugars.
Another GM investment is Coskata, which uses a combination of gasification and microbes to turn carbon-carrying feedstocks, including agricultural and forestry wastes or even trash, into ethanol at $1 a gallon.
Municipal waste can produce 20 billion of gallons of ethanol per year near city centers where the fuel is consumed, said Arnold Klann, CEO of BlueFire Ethanol, who spoke on the conference call. Earlier this year, an executive from Coskata estimated that municipal solid waste could yield about 8 billion gallons per year.
BlueFire recently received permits to begin construction of a trash-to-ethanol plant in Lancaster, Calif., that is expected to produce ethanol at $1 per gallon by September, Klann said. Its plans call for a 17 million-gallon-per-year facility next year and then 55 million-gallon-per-year plants after that.
After pretreating incoming trash, the company's concentrated acid hydrolysis process sprays the trash with sulfuric acid which turns the starchy materials into sugars that are then fermented into ethanol.
The remaining lignin material is burned to partly fuel the operation, meeting 100 percent of its steam requirements and 70 percent of its electricity needs, according to Klann. Using landfill also reduces landfill methane, a potent greenhouse gas, he added.
Company representatives on the conference call said that they need continued supportive government policies, notably loan guarantees, to scale up their operations.
Although these panel speakers were bullish on the future of biofuels, the question of whether the U.S. could grow enough biomass to make one-third of its fuel is still not completely resolved.
An oft-cited 2005 Department of Energy and Department of Agriculture study, nicknamed the "billion ton study" (PDF), concluded that 1.3 billion tons of biomass could be harvested sustainably each year in the U.S. by midcentury, which would meet about one-third of U.S. fuel consumption.
Wheeler said GM-commissioned research done at the University of Toronto reached similar conclusions. She added that the author of the billion-ton study plans to do a follow-on report with updated data.