What is switchgrass?
Filling America's future energy needs is a tall order but switchgrass seems to be up for the challenge.
Thu, Jun 30 2011 at 12:25 PM
Photo: Robert H. Mohlenbrock, USDA/Wikimedia Commons
Ethanol from switchgrass, a perennial plant traditionally used for foraging and decoration, promises to be among the next big biofuel breakthroughs marketed as an alternative to traditional fossil fuel.
In fact, this tall prairie grass that grows naturally across much of North America is being hailed as a model energy crop for ethanol production.
A big reason for the excitement surrounding switchgrass is that it produces more energy than it requires for growth, making it very sustainable, according to U.S. Department of Agriculture research. It absorbs carbon dioxide from the air and stores a portion in its extensive root system. This contributes carbon to the soil. Capturing and storing, or sequestering, the carbon underground reduces greenhouse gas emissions.
Long known for its soil conservation benefits, switchgrass generally grows inexpensively on marginal land unsuitable for other crops. It is also very tolerant of high temperatures, poor soils, flooding and drought, while also being resistant to pests and plant diseases, according to national agricultural reports.
Switchgrass studies have focused lately on ways to improve the yield and make it more cost-effective through breeding and genetics. At the same time, commercial applications are moving forward to convert dedicated biomass crops into clean-burning sustainable fuel.
Despite the promising advances, a few recent federally-funded studies caution that switchgrass may not be the ultimate biofeedstock option for all conditions and areas. It won’t be ready for a while to compete effectively and on a large-enough scale with starch- and sugar-based feedstocks, let alone petroleum-based gasoline, the studies show.
Biofuels on the rise?
The federal Renewable Fuels Standard requires that 16 billion gallons of renewable fuel from cellulosic sources such as switchgrass enter the transportation market in 11 years. The European Union set its target at 10 percent of transportation fuels from biofuel.
At the moment, most ethanol is derived from starch- and sugar-based feedstock. Corn is the feedstock of choice for the vast majority of ethanol production, the U.S. Department of Energy reports. Brazil, the world’s second largest ethanol producer behind the U.S., uses sugar cane.
Those ethanol sources could be limited in the future because of concerns about the impact of diverting food crops to biofuel, the Department of Energy says.
That’s where a non-food, non-waste plant fiber such as switchgrass has the advantage.
The hardy, fast-growing grass has the potential to yield more biomass per acre than starch crops without impacting food crops and requiring less fertilizer.
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