Cleaner diesel from recycled tyres

Old tyres can be completely recycled into low-emission diesel engine oil, according to engineers from the Queensland University of Technology (QUT).

The oil is extracted from end-of-life tyres in a process developed by Green Distillation Technologies (GDT) — an Australian company which has developed award-winning technology to turn car and truck tyres into carbon, oil and steel. It was tested by a team led by Professor Richard Brown at QUT’s Biofuel Engine Research Facility under several different conditions.

“We tested the oil which GDT produces from both recycled natural and synthetic rubber tyres in 10% and 20% diesel blends,” said PhD student Farhad Hossain.

“We found a 30% reduction in nitrogen oxide, which contributes to photochemical smog, and lower particle mass, which means fewer problems for emission treatment systems.”

As explained by GDT Chief Operating Officer Trevor Bayley, the extraction process leaves “nothing wasted and even uses some of the recovered oil as the heat source”.

“Carbon is the most common recovered ingredient and the steel rim and framework is the third most common ingredient, while the oil is the most valuable,” he said.

As well as servicing the transport industry, Bayley said the oil could also be used as a heating fuel or further refined into automotive or aviation jet fuel.

“The potential of this source of biofuel feedstock is immense, and it is more sustainable than other bio-oils from plants such as corn or algae,” he said.

“A recycled 10 kg car tyre yields 4 litres of oil, 1.5 kg of steel and 4 kg of oil, and a 70 kg truck tyre provides 28 litres of oil, 11 kg of steel and 28 kg of carbon.”

Bayley revealed that GDT plans to have the first fully operational commercial plant delivering eight million litres of oil a year from mid-2017, followed by a mining tyre processing plant.