Car tyres made from trees, grasses in the offing

'Green' car tyres - made from trees and grasses - may soon be a reality, thanks to scientists who have developed a new technology to produce a key molecule in automobile tyres using renewable resources found right in our backyards.

Conventional car tyres are viewed as environmentally unfriendly as they are predominately made from fossil fuels.

The new car tyres produced from biomass that include trees and grasses would be identical to existing car tyres with the same chemical makeup, colour, shape and performance.

"Our team created a new chemical process to make isoprene, the key molecule in car tyres, from natural products like trees, grasses, or corn," said Paul Dauenhauer, an associate professor at the University of Minnesota in the US.

"This research could have a major impact on the multi-billion dollar automobile tyres industry," Dauenhauer said.

Currently, isoprene is produced by thermally breaking apart molecules in petroleum that are similar to gasoline in a process called "cracking."

The isoprene is then separated out of hundreds of products and purified. In the final step, the isoprene is reacted with itself into long chains to make a solid polymer that is the major component in car tyres.

Biomass-derived isoprene has been a major initiative of tyre companies for the past decade. However, renewable isoprene has proven a difficult molecule to generate from microbes and efforts to make it by an entirely biological process have not been successful.

Scientists have focused on a new process that begins with sugars derived from biomass including grasses, trees and corn.

They found that a three-step process is optimised when it is "hybridised," meaning it combines biological fermentation using microbes with conventional catalytic refining that is similar to petroleum refining technology.

"Economically bio-sourced isoprene has the potential to expand domestic production of car tyres by using renewable, readily available resources instead of fossil fuels," said Frank Bates, a polymer expert at the University of Minnesota.

"This discovery could also impact many other technologically advanced rubber-based products," he said.

The study was published in the journal ACS Catalysis.