Australasian Science: Australia's authority on science since 1938
Tyres Recycled into a Cleaner Diesel Blend
Old tyres can be completely recycled into lower-emission diesel engine oil instead of being dumped in highly flammable stockpiles that become breeding grounds for malaria and dengue-carrying mosquitoes.
“Globally, 1.5 billion tonnes of tyres are discarded each year,” said Prof Richard Brown of Queensland University of Technology. “Australia alone will generate 55 million disused tyres a year by 2020.
“Getting rid of old tyres in an environmentally friendly way is a universal nightmare. Stockpiles of used tyres around the world are a health hazard, as demonstrated by the recent Broadmeadows fire in Victoria, which was difficult to put out and generated huge amounts of toxic smoke.”
Brown’s team has tested the oil extracted from old tyres in a process developed by Australian company Green Distillation Technologies (GDT). When the oil was blended with diesel it produced a fuel with reduced emissions and no loss of engine performance.
“We tested the oil which GDT produces from both recycled natural and synthetic rubber tyres in 10% and 20% diesel blends,” explained 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 emissions-treatment systems.”
GDT’s chief operating officer, Trevor Bayley, said the oil could also be used as a heating fuel or further refined into automotive or aviation jet fuel. “The process recycles end-of-life tyres into oil, carbon and steel, leaving nothing wasted, and even uses some of the recovered oil as the heat source,” Bayley said.
“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. 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.
“A recycled 10 kg car tyre yields 4 litres of oil, 1.5 kg of steel and 4 kg of carbon, and a 70 kg truck tyre provides 28 litres of oil, 11 kg of steel and 28 kg of carbon.”
GDT plans to have the first fully operational commercial plant delivering eight million litres of oil per year from the middle of the year, followed by a world-first mining tyre-processing plant in either Queensland or Western Australia.