Biological fuels received a black eye earlier in the decade when the rush to embrace corn ethanol came to a crashing halt as the technology's economics and carbon footprint became clear, Doug Struck wrote in Part I ("Reality Pricks Corn Ethanol's Bubble").
William Frey holds up a beaker of brown slush, plucked from the clutch of an automated carousel swirling dozens of glass containers. The liquid, a mix of ground corn stocks and a microscopic organism named the Q-Microbe, may just be the fuel of the future, Frey says.
"We're on the right path. This works," says Frey, president of Qteros, a company outside Boston that is reaping ethanol in their labs from colonies of a single-celled bacteria found in the dirt beside a Massachusetts reservoir. "If money were no problem, we could build plants today."
Qteros is part of a rush to develop what one expert calls "the holy grail" of energy, a biological-based fuel that can replace petroleum. The potential reward is huge: saving the world from catastrophic climate change, powering our society with abundant new energy, and ending a global economic imbalance now tilted toward nations that happen to sit atop oil reserves.
President Obama is betting that reward can be had. He has announced an effort to promote biofuels, pledging $786.5 million dollars of stimulus money to research and development. Biofuels will be "an integral part of this new 21st-century American economy," proclaimed Obama's agriculture secretary, Tom Vilsack, in presenting the plan May 5.
The good news is that science has the answers; researchers at Qteros and dozens of other labs have succeeded in a variety of ways to make fuel from plants and organisms. The bad news is that all face daunting challenges to producing fuel in the volume we need at a price we can afford. And, as with corn ethanol, there are certain to be unforeseen consequences of ramping up to a large scale.
Corn-based ethanol succeeded quickly on an industrial scale because most of the elements were in place: vast cornfields, an infrastructure for moving corn to processors, and an age-old fermentation science used by moonshiners. The new generations of biofuels do not have all those advantages.
The search for new strategies generally falls in two camps: ways to use organic stuff other than corn to make ethanol, and ways to manipulate organisms to produce a different fuel identical to gasoline or diesel.
The search for a better ethanol — "cellulosic ethanol" — is farthest along, hitching on the experience of corn ethanol. Almost any organic matter — from the leftover corn stalks after harvest to garbage to grass to sawdust — has cellulose that can be fermented into ethanol. Researchers are exploring ways to use acid or enzymes to break the cellulose away from the lignin that gives the plant its structure. Cows and sheep do this in their stomachs naturally.
Its promoters say corn-based ethanol is only the flawed first version, and that cellulosic ethanol will end the competition of food with fuel, and spread the organic sources of ethanol over a much larger and diverse landscape.
They envision vast fields of switchgrass, a tall prairie grass, grown without water on vacant land, and harvested for fuel. They note that the lignin plant structure that is left after cellulose and carbohydrates are taken can be burned to help fuel the conversion process, giving the whole operation a much better greenhouse gas advantage than simply fermenting corn.
Congress has written this idea into the law with the same vigor that it embraced corn ethanol. In the 2007 Energy Independence and Security Act, Congress said that of the 36 billion gallons of biofuel it wants produced by 2022, 15 billion gallons must come from corn-based ethanol and at least 16 billion gallons from cellulosic biofuels.
But that view of the future of cellulosic ethanol may be rosy. There is "no way" the industry will meet even the next step on the production schedule set out by Congress, according to Ethan Zindler, head of North American research for New Energy Finance. The renewable fuel standard passed by Congress calls for 100 million gallons of cellulosic ethanol in 2010, but the actual production capacity from experimental plants is only about 3 to 4 million gallons, he said. "The expectations were not entirely realistic."
Even supporters like the Natural Resources Defense Council, which just last year had waxed enthusiastic that cellulosic ethanol is "too good to be true," are now more reserved.
"It's hard for anyone to sit down and think through the full consequences and interactions," acknowledged Nathanael Greene, director of renewable energy policy for the NRDC in New York. "If we get the accounting wrong, we won't get biofuel. That will make solving global warming very hard. On the other hand, if we get the accounting wrong, that will increase global warming."
Ethanol — no matter how it is made — has an unfortunate affinity for water, which accumulates in pipelines, so ethanol cannot be shipped in the existing fuel infrastructure. It has to be shipped by tanker truck. It also has relatively low energy density, meaning it cannot realistically power airplanes, ships or even trucks, which would have to carry too much fuel to move their mass.
And, even if cellulosic ethanol is not competing with food, there are limits to the amount of biomass that we can find or grow to make the ethanol. A 2005 study by the departments of Energy and Agriculture estimated that farming leftovers — logging waste, pulp processing waste and the harvest from 55 million acres of new crops — would produce, optimistically, about 1.3 billion tons of biomass a year. Even if every bit of that were converted to biofuels, it would replace only a portion of our transportation needs. A recent study by the government-backed Sandia National Lab estimated that one-third of our transportation fuel needs might be met by cellulosic and corn ethanol by 2030, given "aggressive" biofuel development.
And that relies on assumptions that may not make sense to a farmer, say three researchers at Iowa State. "Cellulosic ethanol is more expensive to produce (than corn ethanol), and switchgrass-based ethanol is more land intensive," said Mindy Baker, Dermot Hayes and Bruce Babcock, in a 2008 study on the economic choices facing farmers. Without higher subsidies, "rational farmers will not grow switchgrass or soybeans for biofuel production, and rational investors will not build these plants."
Despite those hurdles, supporters like Frey at Qteros are optimistic. They see small-scale cellulosic refineries located near switchgrass grown on empty fields, beside pulp paper mill plants, or linked to municipal landfills, producing ethanol and using leftover biomass for co-generation of heat.
Researchers are making strides at increasing the efficiency. By encouraging certain traits in their Q-microbe, Frey said Qteros has increased its ethanol output by 80 percent.
"There's no question our energy future is going to be more diverse than it is now. I think cellulosic ethanol will be the biggest participant," Frey said. "I think it's reasonable to be shooting for providing 50 percent of our liquid transportation fuel with sustainable fuel."
Other researchers are exploring ways to create fuels that are chemically identical to gasoline or diesel, avoiding the drawbacks of ethanol. At the Harvard Medical School, George Church (http://arep.med.harvard.edu/gmc/), a professor of genetics, is using the high-speed genetic splicing method that he developed for the Human Genome Project to produce new concepts of biofuels.
LS9, a San Francisco company founded by Church, makes what it calls "designer biofuels" by genetically re-engineering E. coli bacteria to feed on biomass and excrete fatty acids that are hydrocarbons.
LS9 mixes the engineered bacteria in vats of water with sugarcane, and the company says it can siphon the resulting biofuel off the top and put it straight into diesel gas tanks. The advantage, they say, is that these biofuels do not need the separate transport system required by ethanol, and can be produced from almost any biomass.
But such solutions still will require a massive amount of organic material, whether it is sugarcane or grass or waste wood. Church believes algae can be designed to skip the need for biomass, feeding off of sunlight and any source of carbon dioxide.
And he asserts that the science puzzle of how to create biofuels using organisms is largely finished. "Engineering microbes to make the hydrocarbons you want is a solved problem," he said in a recent interview at Harvard. "I think we know enough about metabolism that it can be handed off to an engineering team."
But the engineering is far from solved. Creation of large ponds for algae, for example, will require vast amounts of increasingly limited water. Some companies, such as Sapphire Energy in San Diego, say algae can be developed to live in wastewater or saltwater so freshwater supplies are not tapped. Algae and other microorganisms can be finicky about temperature, can produce toxins, and the complications of growing vast amounts and harvesting biofuel from them are immense.
For example, GreenFuel Technologies, a spin-off from Harvard and Massachusetts Institute of Technology, was one of the most prominent and promising, using algae to convert industrial exhausts into biofuels. In 2007, algae in the company's Arizona greenhouse grew faster than it could be harvested. It died, one of several complications that beset GreenFuel; the company closed this spring after spending millions of dollars.
But some of energy's biggest players are convinced enough of the potential of biofuels to invest. Exxon Mobil, the oil behemoth, announced this month it would put up to $600 million in a biotech company founded by geonomics pioneer Craig Venter, who has been scouring the globe for rare microbes he hopes to implant in a new species he has called "Synthia." Chevron is working with a synthetic biology company to try to make biodiesel from synthetically altered algae, and DuPont already produces a commercial organic plastic using a synthetic organism.
Many of these companies are simply hedging their bets, spreading money on a variety of development efforts on the theory that something will work, says Zindler of New Energy Finance.
"There's a lot of moving pieces," he notes. "Which technology is best? Until we see a plant that actually produces fuel at scale and at an affordable rate, it's too soon to tell."
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