Just read this article about dry long grass being evaluated as a future bio-fuel.
"Miscanthus -- also known as elephant grass -- promises to be one of five or six options that could help the U.S. to reach its target of replacing 30 percent of gasoline use with biofuels by 2030." - Dr. Stephen Long from the University of Illinois quoted.
Here is another article about exploring the use of switch grass as a bio fuel.
Funny I never thought grass could be so useful, and this time not as a cattle food:-)