Saturday, February 10, 2007 12:20:42 AM
ETHANOL: Best read yet!
Alcohol: Cool solution to global warming?
POSTED 8 FEBRUARY 2007
Last week, the United Nation's Intergovernmental Panel on Climate Charge reported that the link between rising temperatures and carbon dioxide in the atmosphere is stronger than ever.Black and white photo of a man in white jumpsuit pumping gas from antique pump into an antique auto Most of the greenhouse gases come from fossil fuels, so warming will intensify as more people in China, India and elsewhere enjoy the joys of joy-riding in private cars.
Nothing new under the sun: Marketing corn ethanol in 1933. Photo: US Dept. of Energy
In the long run, we will all be dead. But in the short run, we hope humanity can mount an effective response to the warming that has been gathering speed since about 1980.
In countries like the United States that guzzle gasoline like there is no tomorrow, conservation may be the most sensible place to start reducing carbon dioxide. But the Bush Administration is also interested in shifting gasoline production from petroleum to biomass.
They propose to do what whiskey-makers have done for centuries -- ferment corn and distill the product into a liquid fuel. Only the ethyl alcohol won't be called "white lighting," "moonshine," or even "Old Kentucky." It will be called "ethanol," and it will be poured into the gas tank, not down the gullet.
Global warming has caused a dramatic rise in global temperatures since 1980, paralleling the rise in the greenhouse gas carbon dioxide. (A "nonlinear fit" shows a different straight-line relationship for each of four periods.) Courtesy Kevin Trenberth, National Center for Atmospheric Research
Trend shows rising temperatures along with rising carbon dioxide
Let them [cars] drink ethanol
From a global warming standpoint, ethanol, biodiesel and other "biofuels" made from vegetation seem too good to be true: The crops absorb solar energy, are fermented into alcohol and then burned. Then the next biofuel crop pulls all the carbon dioxide they created out of the atmosphere.
Drive all you want, and you don't add any net carbon to the atmosphere. All driving, no warming, in other words.
Graphic follows processing biomass into energy, showing release of carbon dioxide into sunny green environment
Biological sources of energy can convert solar energy into usable fuel; but technological challenges block use of the most promising forms. Graphic: Lawrence Livermore National Laboratory
It's quite a selling point, and the move to ethanol is well under way, spurred in part by a $0.51 per gallon U.S. subsidy. It's possible to make ethanol from corn, and burn it in gasoline. But is it wise? Does corn ethanol really combat global warming?In 2005, 3.9 billion gallons of ethanol were blended into gasoline in the United States; comprising about 2 percent of gasoline sales by volume. The feds estimate 2006 production at more than 4.6 billion gallons. Brazil is making massive amounts of ethanol from sugar cane, and expects to start exports soon.
Most ethanol is blended as a 10 percent additive to gasoline, called E-10. Although many new cars can also indulge in E-85 (85 percent pure ethanol) this stuff is not widely sold at present.
Ethanol contains less energy than the same volume of gasoline, but it also makes less carbon monoxide and other pollution, and is a good, non-toxic additive for cold weather. But as the giant gasoline industry swerves off Petroleum Place and onto Ethanol Avenue, will the result be good -- or too good to be true?
Calling a fuel "renewable" does not automatically make it green. Skeptical? The European Union decided to promote biofuel to counter global warming, and in response nations in Southeast Asia clearcut rain-forests for palm trees that will make palm oil for fuel. Many of the plantations were built on highly organic soil, and when the farmers burned the land to clear it, Enormous wooden barrels deep in the forestthey dumped millions of tons of carbon dioxide into the atmosphere. A biofuel scheme designed to slow global warming actually wound up accelerating warming (see #1 in the bibliography).
2,000-gallon whiskey stills found in a government raid of the Blue Blazes Stills on Catoctin Mountain, Maryland in 1929. The stills that make corn ethanol for your gas tank will be bigger yet! Photo: NPS
So before you convert grandpa's backwoods still into a weapon against climate change, you might want to ask some questions: How much net energy do we get from moonshine motorfuel? What is the global warming impact of the ethanol industry?
And will fermenting mountains of corn affect our food supply?
Let them eat ... gasoline?
The United States burns about 9 million barrels (1.4 billion liters) of gasoline each day, so we'll have to ferment a big heap of corn to slow global warming. One harbinger of the effect this will have on the food supply appeared last month. The San Francisco Chronicle quoted Peter Navarro, a business professor at University of California at Irvine, on the subject of tortillas in Mexico: "The price of oil is driving up the price of corn (because of increased ethanol production), which is driving up the price of tortillas."
More food shortages loom, according to Lester Brown of the Earth Policy Institute. Brown claims that a recent report from the U.S. Department of Agriculture drastically underestimated the biofuel demand for corn. Brown calculated that the ethanol plants in operation, under construction, or being planned will devour "139 million tons, half the 2008 harvest projected by USDA," in the 12 months starting September 1, 2008.
Sign on Ohio Turnpike says $2.99 per gallon
Gas prices spiked to $3 a gallon in the United States last summer, sparking concern - and some hope for fuel conservation. © David Tenenbaum
That mountain of corn -- half the giant American crop -- would "yield nearly 15 billion gallons of ethanol, satisfying 6 percent of U.S. auto fuel needs," Brown continued (ethanol now supplies about 2 percent).
The numbers seem solid. The ethanol industry's Renewable Fuels Association says 11.8 billion gallons are on line or under construction. That's about 20 percent below Brown's figure, but the association did not count facilities in the planning stage.
If the current subsidy for ethanol remains, 15 billion gallons of motoring moonshine will cost the U.S. Treasury $7.5 billion. More important, as Brown notes, grain prices will inevitably rise. "This unprecedented diversion of the world's leading grain crop to the production of fuel will affect food prices everywhere. As the world corn price rises, so too do those of wheat and rice, both because of consumer substitution among grains and because the crops compete for land."
Indeed, in early February, the price of corn reached $3.23 per bushel in the United States, a 50 percent rise in a year, and reserves were at their lowest in 10 years.
Maybe we should ask: Exactly how much net energy will corn ethanol provide?
Renewable fuel: Help for global warming?
In terms of the greenhouse warming that's cooking the home planet, here is the renewable-fuel question that matters: How much greenhouse gas gets made by Cars and trucks in a traffic jam, with Chicago skyscrapers in the backgroundburning comparable amounts of various fuels? (Okay, it might be even smarter to measure passenger miles per ton of greenhouse gas produced, but given the furious pace of global warming, should the perfect be the enemy of the good?)
Gazillions of gallons of gasoline get gobbled on traffic-clogged highways, along with an ocean of diesel. Could crops provide a significant amount of motor fuel, and cut greenhouse gases at the same time? Photo: ©David Tenenbaum
When Alexander Farrell of the Energy and Resources Group at the University of California at Berkeley examined greenhouse-gas production from ethanol, he learned the importance of the process: "How do you make the ethanol? The number of greenhouse gases associated with ethanol varies a great deal, by a factor of two or three, depending on the feedstock and process used to convert feed into fuel."
In a 2001 study of U.S. ethanol production (see #2 in the bibliography), Farrell calculated that corn-derived motoring-moonshine "probably yielded a slight decrease in greenhouse gases, per unit of energy delivered to the car, in the neighborhood of 15 percent." He admits "there are many uncertainties associated" with this calculation, ranging from a 36 percent reduction to 29 percent increase.
Getting something for nothing, or getting nothing for something?
As the United States tries quelling its swelling thirst for fossil fuels, biofuels are also being hyped as a renewable way to move vehicles -- as fuel from the sun. But in this age of ballooning energy shortages, some skeptics wonder how much energy you get back from biofuels.
When you tap an energy source, you want more get than give. This, after all, is the payback from petroleum: You get 15 joules of gasoline energy for your gas tank if you give 1 joule of energy to drilling, refining and shipping the fossil fuel.
That's a 15 to 1 payback. Unfortunately the corn-ethanol payback is not so happy. Depending on which study you believe, motoring moonshine yields 0.75 to 1.5 times the energy you invest to make it.
Payback calculations count the energy flow in and out of the ethanol process. Growing plants use solar energy to make the sugars and carbohydrates that can be converted to ethanol. But this "biomass energy" is not free: to get it from corn, you need to plow, plant, fertilize, cultivate, harvest, dry and transport the crop. Then you need to ferment the kernels into ethanol, and distill (concentrate) the alcohol into fuel. Each step takes energy.
Arrows illustrate the process from corn to ethanol to energy
Biofuel absorbs solar energy and allows the endless recycling of carbon, as shown in this helpful Department of Energy graphic. It's a jim-dandy picture, until you recall how it ignores the huge pile of conventional energy needed to grow and process biofuels. To be helpful, we added those in red. Improved from DOE.
What's in it for me?
To get gasoline from petroleum, you give energy exploring, drilling, transporting, storing and refining. You give the energy equivalent of 1 liter of gasoline, and you get 15 liters of gasoline. The 3.2 billion liters (20 million barrels) of crude oil guzzled each day in the United States proves that 15 to 1 is an acceptable payback.
Let's return to the net energy calculation. A 1991 study by David Pimentel of Cornell University (see #3 in the bibliography) found that corn ethanol would produce only about 0.75 times the input energy -- in other words, it was an energy sink, not a source.
Estimates of the energy payback from corn ethanol have risen over time
Estimates of net energy production from corn ethanol are gradually rising. It's safe to expect further improvements, but also legit to ask: "Is the corn-ethanol game worth the candle?" Graph: NREL
Ethanol advocates have since contested Pimentel's results, claiming that he misunderestimated corn production per acre, for example. But even if we accept that corn ethanol has a positive payback (the highest estimates reach about 1.8), is the game worth the candle?
In 2006, Robert Costanza and colleagues calculated that a middle-range positive payback (give 1 liter to get 1.2 liters) would mean that a good corn crop would yield "a mere 60 gallons [of ethanol] per acre net yield, not even two fill-ups for an SUV. The entire state of Iowa, if planted in corn, would yield approximately five days of gasoline alternative" (see #4 in the bibliography).
Corn ethanol: Not all it's cracked up to be?
Costanza, who is now director of the Gund Institute for Environmental Economics at the University of Vermont, should know about net energy. In 1984, he first proposed to analyze biofuels with an approach he called Energy Return on Investment (EROI; see #5 in the bibliography).
The EROI method compares the output of an energy source to its fossil-fuel inputs. If you spend too much energy getting energy, you'll have less left over to haul your carcass to the mall, power your Wii, or heat your house.
If corn ethanol returns only 1.5 times as much energy as it consumes, should we bother. Or is 'energy return on investment' the wrong question?The exact payback of a particular energy source is, Costanza, acknowledged on the phone, "an open question, but the numbers do not put these energy sources anywhere near what we been used to with oil or coal. That's the real concern. We are going to be putting lot a more energy back into just getting energy."
These slightly-better-than-breakeven numbers for corn ethanol are based on faulty analysis, says Farrell. Comparing energy "give" to energy "get" makes little sense it this case, because the point of converting corn into ethanol is to make high-value vehicle fuel.
Corn ethanol does not simply increase the energy output by a factor of 1.2 or 1.5. Instead, it makes motor fuel from solar energy (which makes sugar in the corn kernels), coal (source of electricity for the ethanol plant), natural gas (source of corn fertilizer), and diesel fuel (which runs tractors and trucks).
So instead of talking about net energy, Farrell says we should be discussing the benefits of energy conversion. That, he says, is how we evaluate comparable technologies. "Do we really pay attention to how much energy went into mining the coal or natural gas that makes electricity for our computers? No, you think the electricity is really valuable. The net energy is really lousy for electrical conversion [in a generating plant], but we don't care." Electric generating plants and ethanol plants both "take fuel of one quality in, and produce energy of a higher quality," he says.
Silos, tubes and huge outbuildings on the open green prairie
Giant fermenter-distilleries are springing up around the corn belt, ready to convert corn to motor fuel. Photo: NREL.
Fomenting ferment
Although the energy return for corn ethanol sounds straightforward (you just measure inputs and outputs), "There are a lot of uncertainties about how you measure the input and output, where you draw the system boundaries," says Cutler Cleveland, professor of geography and environment at Boston University. "Do you include the energy used to pump irrigation water? Some analysts don't use that. What about the energy consumed by laborers on the farm?" If half your corn crop is getting fermented into fuel, do you count the energy needed to make tractors and tractor factories?
One key "system-boundary issue" concerns the effect of growing so much corn on the soil. "If we are growing corn and depleting the soil, it's not sustainable," says Costanza. "The yield will go down unless we put organic matter back on the soil, and that has a real cost in energy or dollar terms." It may be difficult to pinpoint the dollar cost of soil degradation, but cost-benefit analysis requires it, Costanza says. "It's better to be approximately right than precisely wrong. If you leave [soil costs] out and assume they are zero, you are wrong."
Corn ethanol may reduce greenhouse gases, but how much?And while it may be true, as Farrell says, that petroleum (mainly diesel fuel for tractors, harvesters and trucks) is only a minor input to corn ethanol, a vast amount of natural gas is used to make corn fertilizer, and natural gas is a tip-top fossil fuel. It has low carbon emissions, and it can even power cars without conversion to fertilizer to grow corn for ethanol.
A further issue concerns the dried-out junk left over after the yeast finish fermenting the corn mash. These "brewer's dried grains" can be added to cattle feed (up to about 20 percent of the feed), so it seems legitimate to add their energy value to the ethanol's fuel value, which raises the payback. But soaring ethanol production may flood the market for dried grains. As Cleveland observes, "You can't burn animal feed in your Toyota." Under those circumstances, is it still legit to count the energy value of the cow-food?
Greenhouse gases
Confused yet? Here's another factor in the biofuel debate: All the energy in gasoline comes from fossil fuel, but corn ethanol contains some solar energy. "Corn ethanol still has better energy balance than petroleum," says Bob Wallace, of the National Bioenergy Center at the National Renewable Energy Laboratory. "Far less fossil fuel is used per gallon of ethanol produced, and it has much stronger environmental benefits per gallon, in terms of greenhouse gas reduction, carbon reductions."
Despite the unlimited level of squabbling on the subject of corn ethanol, here's the weird part: Few (if any) experts expect corn ethanol to "make" a whole lot of energy, or to significantly reduce greenhouse gases. "I don't think corn will ever displace gasoline," says Wallace. "It's not possible to grow enough corn to make a serious displacement of petroleum fuel. We used 120 billion gallons of gas in 2004; there is no way we could make that much corn ethanol."
In other words, no matter what you may have heard, corn ethanol will not stem global warming. Any chance we could make moonshine motorfuel from cellulose?
Celling cellulose
As we've seen, corn ethanol is not going to cure the twin crises of global warming and fuel shortage. But beyond the corn-fuel cornucopia looms a much larger source of Modern fuel pump offers three grades of gasolineethanol: cellulose. Cellulose is the general term for a combination of ingredients found in the plant cell wall, including hemicellulose, lignin, and the cellulose molecule itself; which is a stable, long-chain structure made of sugar sub-units.
This biofuel filler-up in Santa Fe, NM, offers a choice of renewable fuels. But being "renewable" does not automatically make a fuel an environmental winner. Photo: American Solar Energy Society
If you can get at those sugars, you can ferment them, but they are difficult to isolate. Cellulose can come from wood wastes, crop wastes, and energy crops like switchgrass and fast-growing trees. Most plans for "cellulosic ethanol" would not compete with food crops; a major advantage over corn ethanol. Overall, the U.S. Department of Energy wants to find a source for 1 billion tons of biomass per year. This mountain of cellulose would mainly be converted into fuel, but also make raw materials for the chemical industry.
Switching to switchgrass?
Although crops like switchgrass are getting considerable attention, essentially no cellulosic ethanol is on the market, due to the high cost of processing. For one thing, cellulose biomass has a low energy density, so it is expensive to transport. Removing cornstalks or other crop wastes for biomass can also hasten erosion of soil, and reduce its humus content, and guidelines for safe biomass removal remain to be written.
A field of wafting, brown blades of grass beneath a lone tree
Energy crops like switchgrass may be cheap enough to fuel biomass fermenters or power plants. That could help revitalize rural economies, but some technological, economic and environmental questions remain. Photo: American Solar Energy Society
Before cellulose can be fed to fermenting microbes, it must be broken apart, which takes a lot of energy because cellulose is so strong (to see the problem from a different point of view, cellulose is simply good at its job -- supporting plants). "Over millions of years of evolution, plants have done everything they could to make sure cellulose is not broken down," says Bob Wallace, biomass project manager at NREL.
Wallace says enzymes (organic molecules that work as catalysts) are a promising way to break cellulose down to glucose. Over the past few years, he says, NREL has achieved a 20-fold reduction in the cost of the fungal enzymes used for degrading cellulose. (The helpful fungi were discovered devouring soldiers' cellulose belts in the South Pacific during World War II.)
"We want to get another two- or three-fold reduction in the enzyme cost," Wallace says, adding that the cost of cellulosic ethanol has dropped fast, from about $5 to 6 per gallon in 2000 to about $2.25 now, mainly due to those cut-rate enzymes. For comparison, corn ethanol now costs $1.10 to $1.20 per gallon at the distillery. "The goal is by 2012 to be competitive with corn ethanol, and by 2020, to be competitive with gasoline," says Wallace.
Fermenting super-yeast
As the computer proves, technologies tend to get better and cheaper with time. In biofuels, a key area for improvement is the yeast that convert sugars to alcohol. These little fungi put themselves in an awkward spot because their metabolic byproduct, ethyl alcohol, is toxic to them. Your (skinned) knee probably knows that alcohol is a great microbicide, and wine stops fermenting at about 12 percent alcohol as the miraculous microbes start to shut down, doubtless woozy from their own ethyl alcohol.
As yeast ferment, they foul their own nest.
Seen under a microscope, spheres of fungi tower over smaller rods of bacteria.
These globes are Saccharomyces cerevisiae, a species of yeast used for millennia to brew wine and beer, and now used to make ethanol from corn. The rods are Escherichia coli bacteria. A recent study points to a new way to help this fungus make cheaper ethanol. Photo: Wikipedia
Many scientists have tried to breed yeast that tolerate a higher concentration of ethanol and produce stronger alcohol faster. A group at MIT has just reported a new way to create a yeast that tolerates a higher ethanol concentration and makes the moonshine 69 percent faster. The researchers used a new tactic: instead of moving genes, they altered genes that control other genes through what they call transcription factors.
Pie chart sliced four ways, illustrating levels of energy used, transportation guzzles most gas
Transport fuels, particularly gasoline, guzzle one-third of American energy use. As global warming proceeds, the push is on to find fuels that cause less environmental damage. Graphic: American Solar Energy Society
The new yeast seemed at ease in the fermenter, says MIT chemical engineer Gregory Stephanopoulos. "The cells grow better and faster. They produce more ethanol, and produce it faster. On all counts, they are more robust" (see #6 in the bibliography). "We have a different method for engineering tolerance to ethanol," Stephanopoulos added, "but it could also apply to other toxic compounds which are present" in other types of biomass.
Microbial future shock
Currently, given the questions surrounding corn ethanol, many people believe cellulosic is the preferred source of moonshine-motorfuel. "Cellulosic ethanol is a far better feedstock for the energy balance," says Wallace. "As the price and conversion costs come down, it will really make the questions about corn a moot point."
Further down the line, experimental technologies may be used to extract the solar energy stored in many organic wastes. Tim Donohue, a professor of bacteriology at the University of Wisconsin-Madison, who has just submitted a large grant to the Department of Energy for a regional biomass research center, says the challenge reaches beyond cellulose. He envisions "microbial biorefineries" that generate electricity, ethanol, hydrogen, and other useful chemicals from plant wastes. Some of these biorefineries would contain photosynthetic bacteria that get some power directly from sunlight.
Monstrous green combine shoots grain into waiting grain truck
Corn grain is the root of today's ethanol market; in the future, corn stalks could become almost as valuable. Photo: American Solar Energy Society
In the short run, Donohue admits, ethanol is the name of the game. "There is a lot of push to make ethanol faster, cheaper; it's being done because we know how to do it. In 10 or 15 years, we hope to have a whole suite of facilities that can convert biomass into different forms of energy. Some will work on animal and plant waste at home, or at farms or farm coops. They will be at water treatment plants, or in large factories with organic material that can be converted into energy, heat and useful products. It's a whole new landscape in the energy field, and in 10 to 15 years, it will look very different from what we have today."
http://whyfiles.org/253ethanol/
Alcohol: Cool solution to global warming?
POSTED 8 FEBRUARY 2007
Last week, the United Nation's Intergovernmental Panel on Climate Charge reported that the link between rising temperatures and carbon dioxide in the atmosphere is stronger than ever.Black and white photo of a man in white jumpsuit pumping gas from antique pump into an antique auto Most of the greenhouse gases come from fossil fuels, so warming will intensify as more people in China, India and elsewhere enjoy the joys of joy-riding in private cars.
Nothing new under the sun: Marketing corn ethanol in 1933. Photo: US Dept. of Energy
In the long run, we will all be dead. But in the short run, we hope humanity can mount an effective response to the warming that has been gathering speed since about 1980.
In countries like the United States that guzzle gasoline like there is no tomorrow, conservation may be the most sensible place to start reducing carbon dioxide. But the Bush Administration is also interested in shifting gasoline production from petroleum to biomass.
They propose to do what whiskey-makers have done for centuries -- ferment corn and distill the product into a liquid fuel. Only the ethyl alcohol won't be called "white lighting," "moonshine," or even "Old Kentucky." It will be called "ethanol," and it will be poured into the gas tank, not down the gullet.
Global warming has caused a dramatic rise in global temperatures since 1980, paralleling the rise in the greenhouse gas carbon dioxide. (A "nonlinear fit" shows a different straight-line relationship for each of four periods.) Courtesy Kevin Trenberth, National Center for Atmospheric Research
Trend shows rising temperatures along with rising carbon dioxide
Let them [cars] drink ethanol
From a global warming standpoint, ethanol, biodiesel and other "biofuels" made from vegetation seem too good to be true: The crops absorb solar energy, are fermented into alcohol and then burned. Then the next biofuel crop pulls all the carbon dioxide they created out of the atmosphere.
Drive all you want, and you don't add any net carbon to the atmosphere. All driving, no warming, in other words.
Graphic follows processing biomass into energy, showing release of carbon dioxide into sunny green environment
Biological sources of energy can convert solar energy into usable fuel; but technological challenges block use of the most promising forms. Graphic: Lawrence Livermore National Laboratory
It's quite a selling point, and the move to ethanol is well under way, spurred in part by a $0.51 per gallon U.S. subsidy. It's possible to make ethanol from corn, and burn it in gasoline. But is it wise? Does corn ethanol really combat global warming?In 2005, 3.9 billion gallons of ethanol were blended into gasoline in the United States; comprising about 2 percent of gasoline sales by volume. The feds estimate 2006 production at more than 4.6 billion gallons. Brazil is making massive amounts of ethanol from sugar cane, and expects to start exports soon.
Most ethanol is blended as a 10 percent additive to gasoline, called E-10. Although many new cars can also indulge in E-85 (85 percent pure ethanol) this stuff is not widely sold at present.
Ethanol contains less energy than the same volume of gasoline, but it also makes less carbon monoxide and other pollution, and is a good, non-toxic additive for cold weather. But as the giant gasoline industry swerves off Petroleum Place and onto Ethanol Avenue, will the result be good -- or too good to be true?
Calling a fuel "renewable" does not automatically make it green. Skeptical? The European Union decided to promote biofuel to counter global warming, and in response nations in Southeast Asia clearcut rain-forests for palm trees that will make palm oil for fuel. Many of the plantations were built on highly organic soil, and when the farmers burned the land to clear it, Enormous wooden barrels deep in the forestthey dumped millions of tons of carbon dioxide into the atmosphere. A biofuel scheme designed to slow global warming actually wound up accelerating warming (see #1 in the bibliography).
2,000-gallon whiskey stills found in a government raid of the Blue Blazes Stills on Catoctin Mountain, Maryland in 1929. The stills that make corn ethanol for your gas tank will be bigger yet! Photo: NPS
So before you convert grandpa's backwoods still into a weapon against climate change, you might want to ask some questions: How much net energy do we get from moonshine motorfuel? What is the global warming impact of the ethanol industry?
And will fermenting mountains of corn affect our food supply?
Let them eat ... gasoline?
The United States burns about 9 million barrels (1.4 billion liters) of gasoline each day, so we'll have to ferment a big heap of corn to slow global warming. One harbinger of the effect this will have on the food supply appeared last month. The San Francisco Chronicle quoted Peter Navarro, a business professor at University of California at Irvine, on the subject of tortillas in Mexico: "The price of oil is driving up the price of corn (because of increased ethanol production), which is driving up the price of tortillas."
More food shortages loom, according to Lester Brown of the Earth Policy Institute. Brown claims that a recent report from the U.S. Department of Agriculture drastically underestimated the biofuel demand for corn. Brown calculated that the ethanol plants in operation, under construction, or being planned will devour "139 million tons, half the 2008 harvest projected by USDA," in the 12 months starting September 1, 2008.
Sign on Ohio Turnpike says $2.99 per gallon
Gas prices spiked to $3 a gallon in the United States last summer, sparking concern - and some hope for fuel conservation. © David Tenenbaum
That mountain of corn -- half the giant American crop -- would "yield nearly 15 billion gallons of ethanol, satisfying 6 percent of U.S. auto fuel needs," Brown continued (ethanol now supplies about 2 percent).
The numbers seem solid. The ethanol industry's Renewable Fuels Association says 11.8 billion gallons are on line or under construction. That's about 20 percent below Brown's figure, but the association did not count facilities in the planning stage.
If the current subsidy for ethanol remains, 15 billion gallons of motoring moonshine will cost the U.S. Treasury $7.5 billion. More important, as Brown notes, grain prices will inevitably rise. "This unprecedented diversion of the world's leading grain crop to the production of fuel will affect food prices everywhere. As the world corn price rises, so too do those of wheat and rice, both because of consumer substitution among grains and because the crops compete for land."
Indeed, in early February, the price of corn reached $3.23 per bushel in the United States, a 50 percent rise in a year, and reserves were at their lowest in 10 years.
Maybe we should ask: Exactly how much net energy will corn ethanol provide?
Renewable fuel: Help for global warming?
In terms of the greenhouse warming that's cooking the home planet, here is the renewable-fuel question that matters: How much greenhouse gas gets made by Cars and trucks in a traffic jam, with Chicago skyscrapers in the backgroundburning comparable amounts of various fuels? (Okay, it might be even smarter to measure passenger miles per ton of greenhouse gas produced, but given the furious pace of global warming, should the perfect be the enemy of the good?)
Gazillions of gallons of gasoline get gobbled on traffic-clogged highways, along with an ocean of diesel. Could crops provide a significant amount of motor fuel, and cut greenhouse gases at the same time? Photo: ©David Tenenbaum
When Alexander Farrell of the Energy and Resources Group at the University of California at Berkeley examined greenhouse-gas production from ethanol, he learned the importance of the process: "How do you make the ethanol? The number of greenhouse gases associated with ethanol varies a great deal, by a factor of two or three, depending on the feedstock and process used to convert feed into fuel."
In a 2001 study of U.S. ethanol production (see #2 in the bibliography), Farrell calculated that corn-derived motoring-moonshine "probably yielded a slight decrease in greenhouse gases, per unit of energy delivered to the car, in the neighborhood of 15 percent." He admits "there are many uncertainties associated" with this calculation, ranging from a 36 percent reduction to 29 percent increase.
Getting something for nothing, or getting nothing for something?
As the United States tries quelling its swelling thirst for fossil fuels, biofuels are also being hyped as a renewable way to move vehicles -- as fuel from the sun. But in this age of ballooning energy shortages, some skeptics wonder how much energy you get back from biofuels.
When you tap an energy source, you want more get than give. This, after all, is the payback from petroleum: You get 15 joules of gasoline energy for your gas tank if you give 1 joule of energy to drilling, refining and shipping the fossil fuel.
That's a 15 to 1 payback. Unfortunately the corn-ethanol payback is not so happy. Depending on which study you believe, motoring moonshine yields 0.75 to 1.5 times the energy you invest to make it.
Payback calculations count the energy flow in and out of the ethanol process. Growing plants use solar energy to make the sugars and carbohydrates that can be converted to ethanol. But this "biomass energy" is not free: to get it from corn, you need to plow, plant, fertilize, cultivate, harvest, dry and transport the crop. Then you need to ferment the kernels into ethanol, and distill (concentrate) the alcohol into fuel. Each step takes energy.
Arrows illustrate the process from corn to ethanol to energy
Biofuel absorbs solar energy and allows the endless recycling of carbon, as shown in this helpful Department of Energy graphic. It's a jim-dandy picture, until you recall how it ignores the huge pile of conventional energy needed to grow and process biofuels. To be helpful, we added those in red. Improved from DOE.
What's in it for me?
To get gasoline from petroleum, you give energy exploring, drilling, transporting, storing and refining. You give the energy equivalent of 1 liter of gasoline, and you get 15 liters of gasoline. The 3.2 billion liters (20 million barrels) of crude oil guzzled each day in the United States proves that 15 to 1 is an acceptable payback.
Let's return to the net energy calculation. A 1991 study by David Pimentel of Cornell University (see #3 in the bibliography) found that corn ethanol would produce only about 0.75 times the input energy -- in other words, it was an energy sink, not a source.
Estimates of the energy payback from corn ethanol have risen over time
Estimates of net energy production from corn ethanol are gradually rising. It's safe to expect further improvements, but also legit to ask: "Is the corn-ethanol game worth the candle?" Graph: NREL
Ethanol advocates have since contested Pimentel's results, claiming that he misunderestimated corn production per acre, for example. But even if we accept that corn ethanol has a positive payback (the highest estimates reach about 1.8), is the game worth the candle?
In 2006, Robert Costanza and colleagues calculated that a middle-range positive payback (give 1 liter to get 1.2 liters) would mean that a good corn crop would yield "a mere 60 gallons [of ethanol] per acre net yield, not even two fill-ups for an SUV. The entire state of Iowa, if planted in corn, would yield approximately five days of gasoline alternative" (see #4 in the bibliography).
Corn ethanol: Not all it's cracked up to be?
Costanza, who is now director of the Gund Institute for Environmental Economics at the University of Vermont, should know about net energy. In 1984, he first proposed to analyze biofuels with an approach he called Energy Return on Investment (EROI; see #5 in the bibliography).
The EROI method compares the output of an energy source to its fossil-fuel inputs. If you spend too much energy getting energy, you'll have less left over to haul your carcass to the mall, power your Wii, or heat your house.
If corn ethanol returns only 1.5 times as much energy as it consumes, should we bother. Or is 'energy return on investment' the wrong question?The exact payback of a particular energy source is, Costanza, acknowledged on the phone, "an open question, but the numbers do not put these energy sources anywhere near what we been used to with oil or coal. That's the real concern. We are going to be putting lot a more energy back into just getting energy."
These slightly-better-than-breakeven numbers for corn ethanol are based on faulty analysis, says Farrell. Comparing energy "give" to energy "get" makes little sense it this case, because the point of converting corn into ethanol is to make high-value vehicle fuel.
Corn ethanol does not simply increase the energy output by a factor of 1.2 or 1.5. Instead, it makes motor fuel from solar energy (which makes sugar in the corn kernels), coal (source of electricity for the ethanol plant), natural gas (source of corn fertilizer), and diesel fuel (which runs tractors and trucks).
So instead of talking about net energy, Farrell says we should be discussing the benefits of energy conversion. That, he says, is how we evaluate comparable technologies. "Do we really pay attention to how much energy went into mining the coal or natural gas that makes electricity for our computers? No, you think the electricity is really valuable. The net energy is really lousy for electrical conversion [in a generating plant], but we don't care." Electric generating plants and ethanol plants both "take fuel of one quality in, and produce energy of a higher quality," he says.
Silos, tubes and huge outbuildings on the open green prairie
Giant fermenter-distilleries are springing up around the corn belt, ready to convert corn to motor fuel. Photo: NREL.
Fomenting ferment
Although the energy return for corn ethanol sounds straightforward (you just measure inputs and outputs), "There are a lot of uncertainties about how you measure the input and output, where you draw the system boundaries," says Cutler Cleveland, professor of geography and environment at Boston University. "Do you include the energy used to pump irrigation water? Some analysts don't use that. What about the energy consumed by laborers on the farm?" If half your corn crop is getting fermented into fuel, do you count the energy needed to make tractors and tractor factories?
One key "system-boundary issue" concerns the effect of growing so much corn on the soil. "If we are growing corn and depleting the soil, it's not sustainable," says Costanza. "The yield will go down unless we put organic matter back on the soil, and that has a real cost in energy or dollar terms." It may be difficult to pinpoint the dollar cost of soil degradation, but cost-benefit analysis requires it, Costanza says. "It's better to be approximately right than precisely wrong. If you leave [soil costs] out and assume they are zero, you are wrong."
Corn ethanol may reduce greenhouse gases, but how much?And while it may be true, as Farrell says, that petroleum (mainly diesel fuel for tractors, harvesters and trucks) is only a minor input to corn ethanol, a vast amount of natural gas is used to make corn fertilizer, and natural gas is a tip-top fossil fuel. It has low carbon emissions, and it can even power cars without conversion to fertilizer to grow corn for ethanol.
A further issue concerns the dried-out junk left over after the yeast finish fermenting the corn mash. These "brewer's dried grains" can be added to cattle feed (up to about 20 percent of the feed), so it seems legitimate to add their energy value to the ethanol's fuel value, which raises the payback. But soaring ethanol production may flood the market for dried grains. As Cleveland observes, "You can't burn animal feed in your Toyota." Under those circumstances, is it still legit to count the energy value of the cow-food?
Greenhouse gases
Confused yet? Here's another factor in the biofuel debate: All the energy in gasoline comes from fossil fuel, but corn ethanol contains some solar energy. "Corn ethanol still has better energy balance than petroleum," says Bob Wallace, of the National Bioenergy Center at the National Renewable Energy Laboratory. "Far less fossil fuel is used per gallon of ethanol produced, and it has much stronger environmental benefits per gallon, in terms of greenhouse gas reduction, carbon reductions."
Despite the unlimited level of squabbling on the subject of corn ethanol, here's the weird part: Few (if any) experts expect corn ethanol to "make" a whole lot of energy, or to significantly reduce greenhouse gases. "I don't think corn will ever displace gasoline," says Wallace. "It's not possible to grow enough corn to make a serious displacement of petroleum fuel. We used 120 billion gallons of gas in 2004; there is no way we could make that much corn ethanol."
In other words, no matter what you may have heard, corn ethanol will not stem global warming. Any chance we could make moonshine motorfuel from cellulose?
Celling cellulose
As we've seen, corn ethanol is not going to cure the twin crises of global warming and fuel shortage. But beyond the corn-fuel cornucopia looms a much larger source of Modern fuel pump offers three grades of gasolineethanol: cellulose. Cellulose is the general term for a combination of ingredients found in the plant cell wall, including hemicellulose, lignin, and the cellulose molecule itself; which is a stable, long-chain structure made of sugar sub-units.
This biofuel filler-up in Santa Fe, NM, offers a choice of renewable fuels. But being "renewable" does not automatically make a fuel an environmental winner. Photo: American Solar Energy Society
If you can get at those sugars, you can ferment them, but they are difficult to isolate. Cellulose can come from wood wastes, crop wastes, and energy crops like switchgrass and fast-growing trees. Most plans for "cellulosic ethanol" would not compete with food crops; a major advantage over corn ethanol. Overall, the U.S. Department of Energy wants to find a source for 1 billion tons of biomass per year. This mountain of cellulose would mainly be converted into fuel, but also make raw materials for the chemical industry.
Switching to switchgrass?
Although crops like switchgrass are getting considerable attention, essentially no cellulosic ethanol is on the market, due to the high cost of processing. For one thing, cellulose biomass has a low energy density, so it is expensive to transport. Removing cornstalks or other crop wastes for biomass can also hasten erosion of soil, and reduce its humus content, and guidelines for safe biomass removal remain to be written.
A field of wafting, brown blades of grass beneath a lone tree
Energy crops like switchgrass may be cheap enough to fuel biomass fermenters or power plants. That could help revitalize rural economies, but some technological, economic and environmental questions remain. Photo: American Solar Energy Society
Before cellulose can be fed to fermenting microbes, it must be broken apart, which takes a lot of energy because cellulose is so strong (to see the problem from a different point of view, cellulose is simply good at its job -- supporting plants). "Over millions of years of evolution, plants have done everything they could to make sure cellulose is not broken down," says Bob Wallace, biomass project manager at NREL.
Wallace says enzymes (organic molecules that work as catalysts) are a promising way to break cellulose down to glucose. Over the past few years, he says, NREL has achieved a 20-fold reduction in the cost of the fungal enzymes used for degrading cellulose. (The helpful fungi were discovered devouring soldiers' cellulose belts in the South Pacific during World War II.)
"We want to get another two- or three-fold reduction in the enzyme cost," Wallace says, adding that the cost of cellulosic ethanol has dropped fast, from about $5 to 6 per gallon in 2000 to about $2.25 now, mainly due to those cut-rate enzymes. For comparison, corn ethanol now costs $1.10 to $1.20 per gallon at the distillery. "The goal is by 2012 to be competitive with corn ethanol, and by 2020, to be competitive with gasoline," says Wallace.
Fermenting super-yeast
As the computer proves, technologies tend to get better and cheaper with time. In biofuels, a key area for improvement is the yeast that convert sugars to alcohol. These little fungi put themselves in an awkward spot because their metabolic byproduct, ethyl alcohol, is toxic to them. Your (skinned) knee probably knows that alcohol is a great microbicide, and wine stops fermenting at about 12 percent alcohol as the miraculous microbes start to shut down, doubtless woozy from their own ethyl alcohol.
As yeast ferment, they foul their own nest.
Seen under a microscope, spheres of fungi tower over smaller rods of bacteria.
These globes are Saccharomyces cerevisiae, a species of yeast used for millennia to brew wine and beer, and now used to make ethanol from corn. The rods are Escherichia coli bacteria. A recent study points to a new way to help this fungus make cheaper ethanol. Photo: Wikipedia
Many scientists have tried to breed yeast that tolerate a higher concentration of ethanol and produce stronger alcohol faster. A group at MIT has just reported a new way to create a yeast that tolerates a higher ethanol concentration and makes the moonshine 69 percent faster. The researchers used a new tactic: instead of moving genes, they altered genes that control other genes through what they call transcription factors.
Pie chart sliced four ways, illustrating levels of energy used, transportation guzzles most gas
Transport fuels, particularly gasoline, guzzle one-third of American energy use. As global warming proceeds, the push is on to find fuels that cause less environmental damage. Graphic: American Solar Energy Society
The new yeast seemed at ease in the fermenter, says MIT chemical engineer Gregory Stephanopoulos. "The cells grow better and faster. They produce more ethanol, and produce it faster. On all counts, they are more robust" (see #6 in the bibliography). "We have a different method for engineering tolerance to ethanol," Stephanopoulos added, "but it could also apply to other toxic compounds which are present" in other types of biomass.
Microbial future shock
Currently, given the questions surrounding corn ethanol, many people believe cellulosic is the preferred source of moonshine-motorfuel. "Cellulosic ethanol is a far better feedstock for the energy balance," says Wallace. "As the price and conversion costs come down, it will really make the questions about corn a moot point."
Further down the line, experimental technologies may be used to extract the solar energy stored in many organic wastes. Tim Donohue, a professor of bacteriology at the University of Wisconsin-Madison, who has just submitted a large grant to the Department of Energy for a regional biomass research center, says the challenge reaches beyond cellulose. He envisions "microbial biorefineries" that generate electricity, ethanol, hydrogen, and other useful chemicals from plant wastes. Some of these biorefineries would contain photosynthetic bacteria that get some power directly from sunlight.
Monstrous green combine shoots grain into waiting grain truck
Corn grain is the root of today's ethanol market; in the future, corn stalks could become almost as valuable. Photo: American Solar Energy Society
In the short run, Donohue admits, ethanol is the name of the game. "There is a lot of push to make ethanol faster, cheaper; it's being done because we know how to do it. In 10 or 15 years, we hope to have a whole suite of facilities that can convert biomass into different forms of energy. Some will work on animal and plant waste at home, or at farms or farm coops. They will be at water treatment plants, or in large factories with organic material that can be converted into energy, heat and useful products. It's a whole new landscape in the energy field, and in 10 to 15 years, it will look very different from what we have today."
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