Switchgrass a better biofuel source than corn
Rhett A. Butler, mongabay.com
January 7, 2008
Collecting data from 10 farm sites in Nebraska, North and South Dakota in which farmers grew switchgrass in fields ranging from 7 to 23 acres over a five year period, Marty Schmer, a researcher with the Agricultural Research Service of the U.S. Department of Agriculture, and colleagues found that, on average, switchgrass produced biomass equivalent to 320 gallons of ethanol per acre — more than 60 percent more the average yield for an equivalent area of corn after factoring in fossil fuel use for fertilizers and pesticides. The study also found that average greenhouse gas emissions from cellulosic ethanol derived from switchgrass were 94% lower than those from gasoline.
Ethanol yield for various crops
Net energy yield for various crops
While corn and other annual cereal grains are now primary sources for U.S. ethanol production, the researchers note that perennial crops, like switchgrass, as well as agricultural waste and forestry biomass can be broken down into sugars that can be fermented into ethanol. In the future these could be developed as important feedstocks for cellulosic ethanol that could potentially displace 30 percent of current U.S. petroleum consumption.
"Dedicated perennial energy crops such as switchgrass, crop residues, and forestry biomass are major cellulosic ethanol sources that could potentially displace 30% of our current petroleum consumption," wrote the authors, adding that "improved genetics and agronomics may further enhance energy sustainability and biofuel yield of switchgrass."
"As an indicator of the improvement potential, switchgrass biomass yields in recent yield trials in Nebraska, South Dakota, and North Dakota were 50% greater than achieved in this study."
The authors say the high yield and environmental benefits of switchgrass make it an attractive feedstock for biofuel production relative to annual crops in the United States.
Domestically-produced biofuels have seen a surge in popularity in recent years due to increasing concern over climate change and energy security.
CITATION: Jan Fuglestvedt et al. (2007). Climate forcing from the transport sectors. Proceedings of the National Academy of Sciences January 7-11, 2008.
Switchgrass grown for biofuel production produced 540 percent more energy than needed to grow, harvest and process it into cellulosic ethanol, according to estimates from a large on-farm study by researchers at the University of Nebraska-Lincoln. The study involved switchgrass fields on farms in Nebraska, North Dakota and South Dakota.
High oil prices and growing concerns over climate change are driving investment and innovation in the biofuels sector as countries and industry increasingly look towards renewable bioenergy to replace fossil fuels. Bill Gates, the world's richest man, has recently invested $84 million in an American ethanol company, while global energy gluttons ranging from the United States to China are setting long-term targets for the switch to such fuels potentially offering a secure domestic source of renewable energy and fewer environmental headaches.
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