Submitted to: Biofuels, Bioproducts, & Biorefining (Biofpr)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2008
Publication Date: 10/15/2008
Citation: Mitchell, R.B., Vogel, K.P., Sarath, G. 2008. Managing and enhancing switchgrass as a bioenergy feedstock. Biofuels, Bioproducts, & Biorefining. 2:530-539. Log 221508.
Interpretive Summary: The demand for US finished motor gasoline increased by more than 27 million US gallons per day from 2001 to 2006. Alternative transportation fuels combined with reduced fuel consumption is needed to address this demand. Although numerous energy alternatives to fossil fuel exist, cellulosic ethanol production works well with existing automobile standards, has consumer acceptance, is renewable, and reduces dependence on oil imports. Switchgrass is not a one-size-fits-all bioenergy feedstock. Switchgrass is a North American native and is well adapted to marginal croplands, similar to land enrolled in the Conservation Reserve Program (CRP). Perennials, such as switchgrass have advantages over annual crops for cellulosic biomass because they do not have the annual establishment requirements with associated economic and net energy inputs, they require fewer chemical inputs (herbicide and fertilizer) than annual row crops, they produce large quantities of biomass, and they provide important ecosystem services. Herbaceous perennials do require some level of input to optimize productivity and maintain stand quality. Current switchgrass research is focusing on breeding and genetics to improve biomass and energy yields per unit of land area and improved conversion efficiency and agronomics which includes establishment, fertility management, weed control, and harvest and storage management, and documentation of the value of ecosystem services. Additional research on developing management practices that maintain quality stands over multiple years of harvest, optimize biomass and net energy yield, optimize economic return for producers, and provide beneficial environmental services such as erosion control and carbon storage will enhance the value of using switchgrass for biomass energy.
Technical Abstract: The United States Department of Energy (DOE) has identified switchgrass (Panicum virgatum L.) as a viable perennial herbaceous feedstock for cellulosic ethanol production. Although switchgrass Bioenergy research was initiated by USDA-ARS, Lincoln, NE, USA in 1990, switchgrass research has been conducted at this location since the 1930’s. Consequently, a significant amount of genetic and agronomic research on switchgrass has been conducted for the Corn Belt and Central Great Plains of the USA that is directly applicable to its use as a biomass energy crop. Similar research must be conducted in other major agroecoregions to verify or modify switchgrass management practices (agronomics) for bioenergy production. The technology to utilize switchgrass for producing ethanol using a cellulosic platform or by pyrolysis to generate syngas is advancing rapidly. Regardless of platform, using switchgrass for ethanol production will require the development of improved bioenergy cultivars or hybrids and improved agronomics to optimize production and will introduce competing uses for the land base.