Ethanol research turns to switchgrass
Posted on Thursday, January 10, 2008
HOUSTON — New energy legislation ensures ethanol will play a bigger role in meeting U. S. energy needs in coming years.
But how big will depend on whether researchers can find a cost-effective way to make the renewable fuel from sources other than corn.
A new study bolsters the case for making ethanol from switchgrass, a plant native to North America that grows up to 9 feet tall in dense brushy patches and can thrive in a range of climates.
Its key finding: Switchgrass yields more than five times the energy used to grow it and convert it to ethanol, making it more efficient than corn, the chief crop used to make ethanol in the U. S. today.
The production of switchgrass also yields almost no greenhouse gases since carbon emissions from farm tractors, fertilizer and other steps of the process are absorbed by the switchgrass as it grows, the study said.
The study, published Monday in the Proceedings of the National Academy of Science, is the first large-scale attempt to measure the energy efficiency of switchgrass.
And it could help pave the way for so-called second-generation biofuels derived from switchgrass and other nonfood crops, agricultural waste and wood chips.
The University of Arkansas began studying switchgrass last year, said Chuck West, an agronomist in the Crop, Soil and Environmental Sciences Department who normally studies forage crops.
Several trial plots of five different switchgrass varieties were planted in May at six different locations across the state, he said. During a multiyear effort, researchers will look at yield, weed control and fertilizer rates.
“During the first year you get very little growth,” but yields of up to 7 dry tons per acre are expected by the second or third year, West said.
Similar yields have been produced fairly consistently in Booneville, at the U. S. Department of Agriculture Natural Resources Conservation Service’s Plant Materials Center, where switchgrass research has been under way for several years, he said.
“The main reason we’re doing this research is to develop information that allows us to predict yields under different soil and moisture conditions,” West said. “And we’re going to be looking at how well switchgrass responds to chicken litter” as a fertilizer.
In December, President Bush signed new energy legislation that boosts a mandate for renewable fuel production, mostly ethanol, to 9 billion gallons by 2009 and to 36 billion gallons by 2022. Current production of ethanol is about 6 billion gallons.
More than half of the 2022 target is supposed to be met by second-generation biofuels, even though researchers say technological breakthroughs are still needed to produce the fuels on a large scale.
Some research has found cornbased ethanol requires more energy than it yields, yet the ethanol industry hotly disputes that.
Ethanol produces at least 1. 6 times the energy used to make it, said Matt Hartwig, spokesman for the Renewable Fuels Association in Washington, D. C.
“And our industry continues to improve its efficiency,” he said.
But Kenneth Vogel of the U. S. Department of Agriculture-Agriculture Research Service at the University of Nebraska and one of the authors of the new study, said his report shows switchgrass performs better.
“Corn ethanol is energy positive, but it’s at a lower level than what we’re reporting in this paper,” he said.
Even so, both ethanol derived from corn and ethanol derived from switchgrass will be required to meet future energy needs.
The study collected data from 10 farming sites in Nebraska and North and South Dakota over a five-year period. During that time, farmers were paid to keep track of the diesel fuel, seed and fertilizer they used and the dry weight of the switchgrass they harvested each year, he said.
Previous studies of switchgrass as a biofuel involved only small plots, Vogel said.
Yet there are still questions about how switchgrass, which yields more tons of crop per acre than corn, can be transported to ethanol plants, and how costs can be brought down for second-generation, or cellulosic, biofuels, said John Kruse, a biofuels analyst for economic research firm Global Insight in Waltham, Mass.
In November, it cost roughly $ 2. 50 a gallon to produce cellulosic ethanol versus $ 1. 50 a gallon of corn ethanol, he said.
“Cost-competitive, energy-responsible cellulosic ethanol made from switchgrass or from forestry waste like sawdust and wood chips requires a more complex refining process. But it’s worth the investment,” said Energy Secretary Samuel Bodman in November.
“Cellulosic ethanol contains more net energy and emits significantly fewer greenhouse gasses than ethanol made from corn.”
In May, the U. S. Department of Energy announced that it will provide up to $ 200 million over a five-year period to support the development of small-scale cellulosic ethanol biorefineries in the U. S.
A month later, the department said three research centers will receive $ 375 million in government funding to help spur the development of ethanol from switchgrass, other nonfood crops and agricultural waste products. Information in this article was contributed by Nancy Cole of the Arkansas Democrat-Gazette.
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