Switchgrass Surpasses Expectations

After Congress' announcement that we would have a new RFS (renewable fuels standard) set at 36 billion gallons of ethanol, the need to push hard towards the next generation of plant derived ethanol became increasingly more important. Although corn has been an excellent stepping stone to establish the market and infrastructure for a renewable fuels industry, the need to create ethanol from other biomass sources is needed if we are to stabilize the tug-of-war going on for acreage in the heart of the midwest. One solution is to grow non-grain plants in climates not suitable to corn or soybeans, thus by-passing the potential problems of using too much fertile land for energy rather than food. Switchgrass, a tall perennial grass, has been looked at as a potential replacement because of its ability to grow in areas with lower rainfall totals, lower fertilizer inputs, and its ability to provide a low-erosion habitat for wildlife.


Ken Vogel, a USDA scientist working with the University of Nebraska has just completed a 5 year study looking into the ability for switchgrass to act as a cellulosic biomass feedstock for ethanol. As Vogel points out, the successful renewable fuel substitute should "1) have superior environmental benefits, 2) be economically competitive, 3) have meaningful supplies to meet energy demands, and 4) have a positive NEV" or (Net Energy Value). One of the desires to conduct his farm-scale study was to see if there would be a difference in the values found in real-world situations versus those found on tiny (5 square-meter) test plots.


In fact, Vogel and his team found that the values were even better when applied to their farm scale plots -- mainly because the values did not correlate on a strictly linear level when scaled up. For example, the point out that diesel input values will remain constant for many aspects of the grow of switchgrass, no matter what scale the switchgrass is grown on. What they found was that switchgrass decreased GHG (greenhouse gas) emissions an average of 94% over gasoline, and in some cases neared 100%. Furthermore, the NEV was positive -- approximately 700% was the final ratio indicating that the energy of the final product was more than 7 times the total energy needed to grow the crop. These results seem to qualify Vogel's four criteria to a successful renewable fuels feedstock. One hurtle remains in the development of switchgrass, however, and that is the development of efficient and inexpensive technologies to extract the energy into the production of ethanol. While some plants are capable of using saccharification and hydrolysis to release sugars in the switchgrass, this is very energy intensive and yields slightly less ethanol per acre than corn. However, once the technologies from the ethanol plant's perspective is found, it will be good to have this kind of research to point agriculturalists in the right direction as to what sorts of crops to grow.





To read the article by Vogel et. al in its entirety, go to http://www.pnas.org/cgi/reprint/0704767105v1





Here is a picture from the report showing the farms 10 farms used in the study and their relatively low soil moisture content.

Vogel et. al 2007