The world uses a lot of rubber. In 2020, some 12.7 million metric tons of natural rubber and 14.2 million metric tons of synthetic rubber were consumed worldwide. While synthetic rubber is perfectly suitable for many common household items, manufacturers of heavy-duty products like tires prefer the quality of natural rubber. Thousands of plant species produce rubber naturally but most of the world’s supply comes from “rubber trees,” aka Hevea brasiliensis. It is grown primarily in Southeast Asia now, after being decimated by a fungal disease in its native South America over a century ago. But this single-source supply is troubling to industry stakeholders that worry history could repeat itself.
Tire giant Bridgestone is one of those concerned user. For nearly a decade, the company has been piloting a breeding program for a natural rubber producing shrub called guayule (pronounced why-yoo-lee). The Bridgestone Agro Operations Research Farm opened in September 2013. One year later, the company opened the Biorubber Process Research Center (BPRC) in Mesa, Arizona, and established, in-house, all processes necessary for developing guayule natural rubber for use in tire applications, including research and development, experimental production, and manufacturing. In 2015, Bridgestone produced the first tire made from guayule-derived natural rubber.
Native to Mexico and the American Southwest, guayule is a woody evergreen that can grow on marginal farmland with minimal fertilizer inputs. It also requires very little water, typically using only about 3.5 acre feet of water a year, which is 30% to 40% less than alfalfa, a top crop in the arid states of the U.S. West and Southwest. That’s also why some think it could be a perfect crop for farmers in water-stressed states.
Bridgestone’s agronomists are hoping their breeding efforts can reduce the plant’s water needs even further. The company is also constructing a new Arizona facility that will be able to process 1,000 tons of guayule biomass daily. And even beyond that, Bridgestone is working to build an entire network of markets for the plant in order to incentivize farmers to grow the stuff.
Guayule has dozens of potential uses beyond rubber for tires. It can be processed into a hypoallergenic form of latex, which can be used in gloves and other medical supplies. The extraction process also produces a resin byproduct that can be used in adhesives. What’s more, the biomass residue can be turned into pellets that burn with the same energy as charcoal, making it a potential source for sustainable electricity production. The roots of the plant can also be processed into a natural pesticide.
Sourcing rubber from guayule is not a new idea, with production efforts in the U.S. dating as far back as the 1920s. During World War II, the U.S. government actually turned to guayule for its rubber needs when Japan cut off America’s Malaysian latex resources. The project was scrapped shortly after the war ended though, as it was cheaper and more convenient to just import tree-derived rubber. Guayule requires a series of processes to produce natural rubber consisting of grinding whole plant, solvent extraction, and impurity removal, which is more complex than the natural rubber production process.
Guayule also has a long growing cycle, requiring about two years before it can be harvested. However, it can grow for up to six years, producing three to four cutting before needing to be replanted. It requires little maintenance in the meantime outside its minimal water needs.
Bridgestone has around 200 acres of guayule under production right now. According to the Food & Environment Reporting Network, to meet and sustain Bridgesone’s commercial production goals, the company will need to increase that to 10,000 acres by 2024, then double that to 20,000 acres in 2025. That’s a big reason why Bridgestone is working with University of Arizona, nonprofits, and the USDA on the science to make growing guayule even more efficient. That includes development of specialized processes and equipment tailored to plant and harvest the shrub.
Currently, PanAridus and Yulex are the only commercial producers of guayule natural rubber in the world. Yulex recently partnered with Patagonia to make its Yulex wetsuit from Guayule derived plant stems. (Sources: FERN, Marketplace, Arizona Republic, Associated Press)
