USDA develops method to gauge ethanol potential of switchgrass

By Kris Bevill | August 24, 2011

USDA researchers say they have developed a cost-effective method of determining the ethanol potential of energy grasses that could be used to evaluate the feedstock at the ethanol plant’s loading dock. Using near-infrared sensing (NIRS), Agricultural Research Service scientists measured 20 components in switchgrass, including cell wall sugars, soluble sugars and lignin, that can help determine its potential value to ethanol producers.

NIRS is already used to evaluate corn, but this is the first time NIRS has been employed to predict the potential and actual ethanol yields of grasses, according to the USDA. Actual ethanol yields were predicted by measuring the C6 sugars within the plant cell wall and as soluble sugars. Researchers said the device could also be used to measure the C5 sugars to obtain an estimated potential yield from all of the plant’s sugars.

According to the researchers, the most important aspect of this tool is its low cost. NIRS can be used to estimate ethanol yields from switchgrass for about $5 each sample. Conventional analytical methods cost up to $2,000 for each sample, they said.

NIRS can also be used to aid in the development of high-yielding energy grass strains and is already being put to that use at ARS labs in Nebraska and Wisconsin. A cooperative agreement has been established between ARS and the Near Infrared Spectroscopy Consortium, a group of commercial laboratories, universities and plant research companies, to make NIRS calibrations available to public and private laboratories researching switchgrass and to industries that plan to use switchgrass as an energy source.