(Photo by Andrew Bernier - KJZZ)

Guayule shrubs growing in front of Bridgestone's biorubber process research center in Mesa.

Tire manufacturer Bridgestone has opened a new biorubber research center in Mesa, hoping that a small desert shrub can offer a sustainable alternative to the world’s only source of commercial rubber.

If you were to turn off along one of those long stretches of I-10 between Phoenix and Tucson, you enter what Arizona and major rubber companies hope becomes a major cash crop for the Southwest, fields of small shrubs called guayule.

It’s not naturally found in central Arizona, though it easily adapts to the arid climate. But it will need some help if it is to meet the expectations of commercial interests.

Tire manufacturer Bridgestone recently opened its Biorubber Process Research Center in Mesa where the process of extracting latex from the guayule plant takes place. Plant manager Bob White oversees the operations.

“This building is mainly for grinding the guayule and then sifting it," White said. "Basically, we pulverize it to the point where we rupture the cells.”

After a lengthy and complicated extraction process, only 15 percent of the plant is actually converted into latex, while the remaining biomass is being researched for potential biofuels.

Natural latex produces much tougher rubber substances, making it ideal for high-impact rubber products like airplane tires and wetsuits. Softer passenger tire rubber and latex-free rubber is made from synthetic latexes.    

Right now, all commercial rubber production comes from the tropical Hevea tree, found in southeast Asia. Even though Hevea is productive, producers want to diversify the sources of biorubber.

Bridgestone New Business Director Bill Niaura hopes that Guayule may be a domestic, diverse and sustainable source of latex, though it will take a while.

“The commodity is the same, the source is different," Niaura said. "And our belief is that the macro-trend, long-term future — remember we’re talking 2020, 2050 here, not next year or next month — is that there will be a point where it makes sense to switch from Hevea to something else.”

Guayule is not a commercial crop, so you can’t go to the store and buy its seeds. To grow it, farmers actually have to select individual plants and test them for ideal genetic traits. Dave Dierig manages the guayule farm in Eloy, Ariz..

“We’re able to look at the genotype and find out what everyone one of these genes do and then that’s what we select for," Dierig said.  "So we’re using molecular tools to develop new varieties where we analyze for rubber content, resin content and rubber quality.”   

That rubber content is key to guayule’s success, though the shrub takes about three years to grow enough woody biomass to extract a commercially viable amount of latex, and that’s not easy in the desert. Then there’s the planting process. Then there is getting water to the seeds.  

Walking out to the field, migrant workers are planting the selectively bred seedlings.

“Other people are getting plants ready," Dierig said. "And then a crew follows down each row, makes sure everything gets planted. So it’s really a labor-intensive process."

Even though it’s a desert shrub, guayule still requires as much as 48 inches of water a year for commercial production. That's still a foot less of water than neighboring cotton plants. 

“I think you want the easiest way of irrigating” Dierig said. Which, in this case, is to flood irrigate the guayule plants.

While commercial guayule is still decades into the future, Bridgestone’s Biorubber Process Research Center is ironically next to a massive tire recycling yard that processes old tires into rubber for playgrounds and asphalt fillers.

“Its a constant reminder of our goal to be renewable and sustainable with our products,” White said.

And that is a growing source of rubber that they don’t need to wait for.