[JeffersonRepublic.com]

""Ethanol is blended with petrofuels to increase combustion and decrease pollutants. The problem is, most ethanol now in use is made from corn, and the total energy output/input ratio is about 1.2. This means the net energy gain from corn ethanol is about 21 percent. The energy output/input ratio for switchgrass is estimated at 4.4, representing a net energy gain of 334 percent."

Taliaferro said the ratio is better with switchgrass because it doesn't require the nurturing of row crops and it is perennial, eliminating the need for annual planting."

[Ursus arctos horribilis]

Hmmmn, out west I would think tumble weeds (Russian thistle) and tule reeds.

http://geolit.org/rushranch/tulereeds.htm

[livius]

Grasses have always made a good fuel, although not widely used in modern times. The Romans used to use handfuls of grass to heat their floors (hypocausts), which were raised tile floors with channels underneath for hot air heated by a fire at some point. In certain parts of Roman-colonized northern Spain, up until about 50 years ago, there were still peasant dwellings that used the hot, fast heat of straw under tile floors.

Granted, this is an entirely different system and the new system doesn't depend on burning the grass itself, but it's interesting that an old fuel would come back in some form.