Focus on Fuels: Developing Sustainable Biofuel Crops

Fuels developed from biomass such as sugar or grain crops or algae could be used more widely in the future to power automobiles, homes, industrial manufacturing facilities and airplane engines.

Scientists and engineers at the University of Arizona are on a mission to develop sustainable agricultural biofuel field crops for Arizona and the desert Southwest—crops that will fuel a new industry as well as America's engines.

Biofuels—fuels developed from biomass such as sugar or grain crops or algae—have as many and diverse uses as traditional energy sources and could be used more widely in the future to power many technologies including automobiles, homes, industrial manufacturing facilities and airplane engines.

"There's no doubt that we're going to have biofuels in the future because no matter what, petroleum is a finite resource," said Dennis Ray, a plant geneticist at the College of Agriculture and Life Sciences. "Problems today are not solved by one discipline."

The biofuel development project could benefit Arizona's economy as well as the environment.

"We're looking at rural development. If you have a little industry in this area, you need people to run the processing plant. That means jobs. That means bringing money back into these communities," said Ray. "It's always a much bigger picture for what we're looking at in the long run."

An ideal place for biofuels

Arizona could be home to a thriving biofuel industry in the future, said Mark Riley, professor and department head of agricultural and biosystems engineering.

"We get a tremendous amount of sunlight," said Riley, which enables crops to be grown year-round or off-sequence from other parts of the country.

"A good example is from traditional agriculture. Yuma County in the western part of the state grows 95 percent of the country's winter vegetables because nowhere else can grow vegetables during that time of the year. In that same vein, we could be growing sources of sugar to make ethanol off-sequence from when other regions are growing corn."

"Biofuels don't make sense if you have to transport them long distances," said Riley. "Some of the largest population growth in this country is in the Southwest, and there really isn't yet a whole lot of agriculture geared toward producing fuels."

"We need to be producing the fuels close to where they're going to be used."

Petroleum is transported through an extensive network of pipelines from the Gulf of Mexico and the Eastern Seaboard. The pipes are not completely watertight, so the greater the transport distance, the more water leaks in. This works because petroleum does not mix with water, but ethanol does.

Ethanol, therefore, needs to be transported by truck, so producing it locally would save on fuel and transportation costs.

The sugarcane of the desert

To be a viable biofuel crop for Arizona, the plants need to do well in arid environments. That rules out corn, which requires a lot of water, as an option in most parts of the Southwest.

"There are hundreds of plants that you could use as biofuels," said Ray. "Oil seeds where you can use the oil almost directly for diesel, cellulosic plants where you can break down cell walls into ethanol, and plants like sorghum where you use the sugar to make ethanol."

"I'm a plant breeder geneticist, so what I do is improve or change the plants for whatever's needed," said Ray. "I work on three very different crops. One is lesquerella, which is an oil seed. Another is guayule, a rubber-producing plant that also makes these amazing resins, and these resins can be burned directly or used in all sorts of different ways as a fuel source. And then of course there's sweet sorghum."

Called the sugarcane of the desert, sweet sorghum is one of the most promising crops for biofuel.

"Sweet sorghum is a tall grass, and it grows to about 3-4 meters," said Riley. "It can grow in about 110-120 days, and it produces a substantial amount of ethanol. We think we can get 500-600 gallons of ethanol per acre—generally for corn you get about 300 gallons of ethanol per acre."