The scientists are testing and developing several other crops, including three types of switchgrass and three varieties of perennial grasses in the genus Panicum.

These grasses produce cellulose instead of starch. Like starch, cellulose is made up of chains of sugar molecules held together by what are called glycosidic bonds. However, the orientation of the bonds in a cellulose molecule creates a more rigid structure, making cellulose harder to break down.

"The conversion of cellulose to sugar is a little more difficult than the conversion of starch to sugar," said Ottman. "You can't just do straight chemical hydrolysis. You need enzymes, and these enzymes are expensive."

For now, most of the ethanol production plants in the U.S. process grain crops. But that could change: The cellulosic process should start taking off by 2015, according to the target date of our energy policy, said Ottman.

And perennial grasses as biofuel crops have important benefits. Cellulose is one of the most abundant organic molecules on Earth and could yield an equally abundant source of fuel on the future.

Numerous research questions remain for each crop, including the amount of water and fertilizers needed, when to plant and when to harvest, how far apart to plant the seeds to optimize the harvest and how best to store and transport the fuel once it's processed. Said Ray: "These are all little things that make a big difference."

"The goal of the project, of all these projects, is to have a commercial product," said Ray. "The end goal is to give back to folks who have given to us through funding and in other ways."

The agricultural methods developed in Arizona would work in many arid or semi-arid environments, said Ray, "which actually applies to much of the Earth. So what we do here is transferrable. The desert plants don't know if they're in Chihuahua or Texas. Borders mean nothing to them. It has to do with the environment."

"One hundred and fifty years ago petroleum was used for kerosene for lamps in the Northeast to replace whale oil. In 150 years you wouldn't recognize what we're doing with biofuels now," said Ray. "We're gaining knowledge so that we understand what's needed and how this whole process works."

Biofuels research at the UA is funded by the U.S. Department of Agriculture's Agricultural Research Service, the U.S. Department of Transportation, the Sun Grant Initiative from the U.S. Department of Energy and the UA's College of Agriculture and Life Sciences.