Stories tagged cellulosic

Jan
08
2008

Large scale study shows 540% net energy gain when ethanol is produced from switchgrass

Panicum Vergatum: Switchgrass
Panicum Vergatum: SwitchgrassCourtesy U S Govt

Kenneth Vogel, a geneticist with the U.S. Department of Agriculture in Lincoln, Nebraska, and his colleagues, found that ethanol produced from switchgrass yields 540% of the energy used to grow, harvest, and process it into ethanol.

Their results, published online in Proceedings of the National Academy of Sciences, shows that switchgrass, farmed using conventional agricultural practices on less-than-prime cropland yields only slightly less ethanol per hectare on average than corn.

Farmers planted switchgrass on 10 farms, each of which was between 3 and 9 hectares. They then tracked the inputs they used--diesel for farm equipment and transporting the harvested grasses, for example--as well as the amount of grass they raised over a 5-year period. ScienceNOW Daily News

Switchgrass monoculture or mixed prairie grasses?

Anyone remember our Buzz post "Chalk one up for diversity"? David Tilman in that post is quoted saying, "diverse prairie grasslands are 240 percent more productive than grasslands with a single prairie species"
Now I read:

... Vogel says, is that yields on farms using fertilizer and other inputs, such as herbicides and diesel fuel for farm machinery, were as much as six times higher than yields on farms that used little or no fertilizer, herbicides, or other inputs to grow a mixture of native prairie grasses. ScienceNOW Daily News

Who is right? Can anyone explain why two reputable researchers are getting such different results?