Biofuels from Switchgrass
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The grass stretched as far as the eye could see, and hundreds more miles beyond that. An ocean of grass—deep enough to swallow a horse and rider—swaying and singing in the steady wind of the Great Plains. § The American prairie—tens of millions of acres— once looked like this. But that was centuries ago, before the coming of the white man, the railroad, and the steel plow. Today, corn and beans hold sway, and the remnants of America’s tallgrass prairie are confined mostly to parks and preserves. § Now, though, in research plots and laboratories in the Plains states and even in the Deep South the seeds of change are germinating. The tall, native grasses of the prairie, so vital to our land’s ecological past, may prove equally vital to its economic future. Such grasses once fed millions of bison. Soon, grown as energy crops, they may help fuel millions of cars and trucks, spin power turbines, and supply chemicals to American industries.
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| Test plots of switchgrass at Auburn University have produced up to 15 tons of dry biomass per acre, and five- year yields average 11.5 tons—enough to make 1,150 gallons of ethanol per acre each year. | |
| The U.S. Department of Energy (DOE) believes that biofuels—made from crops of native grasses, such as fast- growing switchgrass—could reduce the nation’s dependence on foreign oil, curb emissions of the “greenhouse gas” carbon dioxide, and strengthen America’s farm economy. The Biofuels Feedstock Development Program (BFDP) at DOE’s Oak Ridge National Laboratory (ORNL), has assembled a team of scientists ranging from economists and energy analysts to plant physiologists and geneticists to lay the groundwork for this new source of renewable energy. Included are researchers at universities, other national laboratories, and agricultural research stations around the nation. Their goal, according to ORNL physiologist Sandy McLaughlin, who leads the switchgrass research effort, is nothing short of building the foundation for a biofuels industry that will make and market ethanol and other biofuels from switchgrass and at prices competitive with fossil fuels such as gasoline and diesel. | |
Not the grass in your backyardFirst, a distinction: switchgrass and your suburban lawn grasses—bluegrass and zoysia grass— are about as similar as a shopping-mall ficus and an old-growth redwood. Switchgrass is big and it’s tough—after a good growing season, it can stand 10 feet high, with stems as thick and strong as hardwood pencils. But what makes switchgrass bad for barefoot lawns makes it ideal for energy crops: It grows fast, capturing lots of solar energy and turning it into lots of chemical energy— cellulose—that can be liquified, gasified, or burned directly. It also reaches deep into the soil for water, and uses the water it finds very efficiently. And because it spent millions of years evolving to thrive in climates and growing conditions spanning much of the nation, switchgrass is remarkably adaptable. Now, to make switchgrass even more promising, researchers across the country are working to boost switchgrass hardiness and yields, adapt varieties to a wide range of growing conditions, and reduce the need for nitrogen and other chemical fertilizers. By “fingerprinting” the DNA and physiological characteristics of numerous varieties, the researchers are steadily identifying and breeding varieties of switchgrass that show great promise for the future. |
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Switchgrass can be cut and baled with standard farming equipment. Yield of dreamsIn the hard, shallow soil of southern Alabama, Dave Bransby is turning cotton fields into swatches of grassland. Some Alabama farmers joke that there’s no soil in Alabama to farm—two centuries of King Cotton and steady erosion haven’t left much behind. Yet Bransby, a forage scientist at Auburn University, has found a crop that thrives there: Among the 19 research sites in the Eastern and Central United States raising switchgrass for the BFDP studies, Bransby’s site holds the one-year record at 15 tons per acre. Those are dry tons weighed after all the moisture’s been baked out. Convert that into ethanol, an alcohol that can fuel vehicles, and it equals about 1,500 gallons per acre. Bransby’s 6-year average, 11.5 tons a year, translates into about 1,500 gallons of ethanol per acre. An added bonus is the electricity that can be produced from the leftover portions of the crop that won’t convert to ethanol. |
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| Many farmers are already experienced at raising switchgrass for forage or to protect soil from erosion. Besides showing great promise for energy production, switchgrass also restores vital organic nutrients to farmed-out soils. | |
| Many farmers already grow switchgrass, either as forage for livestock or as a ground cover, to control erosion. Cultivating switchgrass as an energy crop instead would require only minor changes in how it’s managed and when it’s harvested. Switchgrass can be cut and baled with conventional mowers and balers. And it’s a hardy, adaptable perennial, so once it’s established in a field, it can be harvested as a cash crop, either annually or semiannually, for 10 years or more before replanting is needed. And because it has multiple uses—as an ethanol feedstock, as forage, as ground cover—a farmer who plants switchgrass can be confident knowing that a switchgrass crop will be put to good use.Farmers working in production mode might not match Bransby’s carefully tended research plots, but if the future brings rises in oil prices—or if environmental taxes are eventually imposed on fossil fuels—energy from switchgrass could prove economically competitive with petroleum and coal, making biomass crops attractive to American farmers. And with recent advances in the technology of gasification, switchgrass could yield a variety of useful fuels—synthetic gasoline and diesel fuel, methanol, methane gas, even hydrogen—as well as chemical by-products useful for making fertilizers, solvents, and plastics. | |
Strong environmental rootsAnnual cultivation of many agricultural crops depletes the soil’s organic matter, steadily reducing fertility. But switchgrass adds organic matter—the plants extend nearly as far below ground as above. And with its network of stems and roots, switchgrass holds onto soil even in winter to prevent erosion. Besides helping slow runoff and anchor soil, switchgrass can also filter runoff from fields planted with traditional row crops. Buffer strips of switchgrass, planted along streambanks and around wetlands, could remove soil particles, pesticides, and fertilizer residues from surface water before it reaches groundwater or streams—and could also provide energy. And because switchgrass removes carbon dioxide (CO2 ) from the air as it grows, it has the potential to slow the buildup of this greenhouse gas in Earth’s atmosphere. Unlike fossil fuels, which simply release more and more of the CO2 that’s been in geologic storage for millions of years, energy crops of switchgrass “recycle” CO2 over and over again, with each year’s cycle of growth and use. |
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The road aheadOne reason BFDP researchers are confident that switchgrass can become an important feedstock for ethanol production is the groundwork that’s already been laid by corn growers. U.S. ethanol production from corn currently totals nearly 2 billion gallons a year. Some of this ethanol is blended with gasoline to make gasohol; some is further refined to make gasoline octane boosters; and some is burned, either in pure (”neat”) form or mixed with a small percentage of gasoline, in fleets of research and demonstration vehicles. Looking down the road, McLaughlin believes switchgrass offers important advantages as an energy crop. “Producing ethanol from corn requires almost as much energy to produce as it yields,” he explains, “while ethanol from switchgrass can produce about five times more energy than you put in. When you factor in the energy required to make tractors, transport farm equipment, plant and harvest, and so on, the net energy output of switchgrass is about 20 times better than corn’s.” Switchgrass also does a far better job of protecting soil, virtually eliminating erosion. And it removes considerably more CO2 from the air, packing it away in soils and roots. |
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| Switchgrass offers excellent habitat for a wide variety of birds and small mammals. | |
Back to the futureAt the turn of the last century, America’s transportation system was fueled by biomass: 30 million horses and mules, give or take a few million, pulled buggies, hauled wagons, dragged plows. According to Ken Vogel, a U.S. Department of Agriculture forage geneticist helping develop and test switchgrass for the BFDP, replacing animal power with machine power freed up 80 million acres of U.S. land—land that had been used to grow grass and other feed for these millions of animals. Now, at the dawn of the next century, the wheel could begin to turn full circle. On millions of acres of farm land not needed for food crops, fast-growing energy crops of switchgrass—harvested and converted efficiently to clean-burning, affordable ethanol, methanol, or diesel—could once again supply vast amounts of horsepower. In short, biomass could bring back a 21st-century version of the prairie. And along with the prairie, it could bring a new crop to America’s farms, a boost to U.S. energy independence, and brighter prospects for a clean, sustainable future. According to BFDP and its research partners across the country, that’s a future worth cultivating. |
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Response to Science Articles on Biofuels
Public Misled About What Studies Actually Say
By: Brooke Coleman
On February 8th, several major news outlets covered the emergence of two new studies about the “upstream” or indirect impacts of biofuel production. There was a clear disconnect between what the studies actually said,(1) and what was actually written. The general thesis of both studies is that using pristine lands to grow biofuel feedstock will have serious climate change impacts. Yet, most of the stories suggested or declared that today’s biofuels are worse than gasoline in terms of greenhouse gas (GHG) emissions. Some of the misinformation is directly traceable to the author’s statements.
1. It is simply false to paint Searchinger’s study as a critique of today’s biofuels …
The Searchinger study assumes 30 billion gallons per year (bgy) of corn ethanol use. This is almost 4 times the current U.S. ethanol market (8 bgy), and 2 times greater than the 15 bgy of corn ethanol use required by federal law through 2022.(2)
2. It is misleading for the authors of both the Searchinger study and the Tillman study to claim that today’s biofuels are worse than gasoline with regard to GHG emissions …
Both studies seek to go beyond the current analysis by incorporating indirect “upstream” land use changes into the GHG profile of biofuels. But they fail to incorporate indirect impacts into the petroleum fuel baseline, resulting in a clear “apples to oranges” comparison.
3. The Searchinger study is very clearly a “worst case scenario” analysis, but the article has been promoted as an investigation into the way things are done today …
Among the worst case scenario assumptions are: (a) an inflated ethanol market size; (b) an inelastic supply/demand land use forecast in which one U.S. hectare used for corn results in one hectare planted elsewhere; (c) all new (displaced) hectares are cultivated in pristine ecosystems (prairie, rainforests, etc.) as opposed to some marginal lands.
4. The Searchinger analysis relies on a long series of highly subjective assumptions …
The string of assumptions: we will get to 30 bgy corn ethanol production; increased corn demand spikes corn, wheat and soybean prices, reducing exports of corn, wheat, soybeans, pork and chicken; 10.8 million hectares would need to be planted to fill the void; new hectares would be planted on pristine lands in four countries: China, India, Brazil and the United States.
5. It is misleading to refer to land use impacts as an “omission” from previous biofuel studies …
An upstream/indirect impact is a brand new field of research for any product with incredibly uncertain indicators. These are all “market mediated” effects with dozens of possible socioeconomic, environmental, policy and geopolitical variables. The indirect impacts of oil dependence are countless, and are also omitted.
It is unfortunate that a “worst case scenario” calculation, without a petroleum fuel baseline analysis, was portrayed as a fair and transparent comparison of a business as usual approach. The ongoing analysis of indirect impacts will be incredibly complicated but remains important. The American Biofuels Council and the New Fuels Alliance hopes that future studies will be more balanced and more accurately portrayed by all responsible parties.
(1) The “Tillman study” (“Land Clearing and the Biofuel Carbon Debt”) focuses on the amount of carbon released by the initial cultivation of pristine lands. The “Searchinger study” (“Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through Emissions from Land Use Change) attempts to predict the magnitude of the impact (i.e. how much land use change will actually occur and to what effect).
(2) The study also refers to a sensitivity analysis of slightly lower inputs, but the inputs are still inexplicably large.
Sobering, the oil reality.
Today I attended the Energy Forum and Expo in Grand Junction Colorado. Located in the heart of Western Colorado’s massive energy boom the energy titans were all represented. The event tended to point out the reality of the existing energy industry which is nearly all fossil fuel based. However there were a few renewable energy Representatives there as well.
The morning lecture with Dr. Michael J. Economides was very entertaining and could have lasted another couple of hours. Dr. Economides is a professor of chemical and biomolecular engineering at the University of Houston and is a world renowned expert on energy research and development. His speech was very sobering to say the least. As he sees it we are a fossil fuel based world, period. And when we want to discuss the issue from an American point of view we need to get our facts straight. This is about transportation energy, oil! Nearly 60% of our needs are shipped into the United States every year and it’s growing. However when we hear jargon about the idea of becoming energy independent by reducing our house hold usage he wants to make it very clear; that energy is produced with domestic supplies of fossil fuel. So in order to address energy independence we need to focus on the issue. Oil!
According to Dr. Economides in 1973 the US was using oil to provide 86% of our transportation needs. Today we use 86% and everything is saying we will use 86% in 30 yrs. What? How can this be? Growing consumption needs will require larger amounts of oil to meet our needs and the notion of alternative fuels playing a large part of that are very minimal. He is very direct with the facts about corn based ethanol and biodiesel from oil seed crops stating that these sources represent a small percentage of our overall needs and they lack the ability to supply large amounts. And we need to wake up to these facts in a hurry. We are looking at a century of oil use with a best case scenario of several decades before we can walk away from it.
So security of our oil needs to be priority number 1. Then we need to do everything we can to domestically produce our energy capabilities in order to hold OPEC at least in check.
Hearing what he had to say and realizing this was a very pro fossil fuel event I had to take what he said with a view of disbelief.
However the next speaker was Anup Bandivadekar of MIT who has been studying “Transportation energy challenges and opportunities for the future.” He talked at length about our infrastructure and the cost associated to any major change in our transportation system. His numbers tend to back what Dr. Economides was saying. And when he took it out to 2035 oil is still our major contributor to our supply needs with conservative numbers for alternatives.
I left today realizing that we need to mobilize in a major way if we are going to find a renewable energy solution that will have any major effects in 30 years. We must also realize there is no possible way to turn off oil any time soon. Anup stated that the world is consuming 1,000 barrels of oil a second. Think about that for one second…. there goes a thousand barrels of oil just like that. WOW!
We must not be overwhelmed by this prospect, it took us a 100 yrs to get here and best case scenario it’s going to take that long to figure out a solution. So let’s be realistic and realize we are in this for the long haul and that there is no silver bullet to solve the situation. We need to be adaptable and creative in order to meet the challenge that lies ahead of us.
