Oil from recycled tyres tested in real-world conditions

Australian researchers have tested the performance of oil from recycled tyres in a 2.5 L diesel vehicle under real-world operating conditions. The tests were conducted on a 2017 Hyundai iLoad van, which has an engine capacity comparable to that widely used in light commercial vehicles, SUVs and 4WDs.

The tyre oil comes from tyre recycling technology developed by Australian company Green Distillation Technologies (GDT). The process, known as ‘destructive distillation’, recycles end-of-life tyres into oil, carbon and the steel bead and mesh, leaving nothing wasted — it even uses a percentage of the recovered oil as the heat source.

The oil was previously evaluated on a bench test in Queensland University of Technology’s (QUT) Biofuel Engine Research Facility. Conducted about a year ago under the supervision of Professor Richard Brown, the bench test found that the recycled tyre oil, when it was mixed as a percentage with standard diesel fuel, had exhaust emissions with 30% less nitrogen oxide and lower particle mass than emissions from standard diesel oil, but almost the same performance.

The purpose of the new research was to validate these tests as well as to compensate for what is now known as the ‘Volkswagen Factor’. As before, it was carried out by the Biofuel Engine Research Facility under the supervision of Professor Brown, in association with Dr Tim Bodisco from Deakin University.

The tests were conducted in Brisbane over a two-week period and included stops and starts in the city to simulate the work of a delivery vehicle, followed by hills to check performance and the CLEM7 and Airport Link tunnels for emissions, as well performance on the steep exit inclines. The vehicle was fuelled with a mixture of 10% recycled tyre oil and standard diesel, while separate tests were conducted with 100% diesel to provide a comparison.

“We have been asked why we are adding 10% of recycled tyre oil to the diesel and not using 100% tyre oil as the fuel we are testing,” Professor Brown said. “The answer is that diesel engines in Australia are designed to run on diesel fuel that is refined to a particular standard, while the tyre oil is an unrefined crude oil.”

Dr Bodisco said the on-road tests showed that emissions, in terms of nitrogen oxide per km, varied much more than measurements in the laboratory and overall were found to be both higher and lower than diesel emissions, depending on the traffic and environmental conditions.

“Our conclusion is that tyre oil behaves in a similar way to that of diesel and further evaluation is needed to fully understand why these fluctuations occur in real-world driving,” he said.

It was intended that tests would also be conducted on a Kenworth semitrailer, but these have had to be deferred to a later date. According to Professor Brown, the researchers are keen to investigate the inconsistencies further “when we do the on-road tests on the semitrailer truck under load”.

GDT Chief Operating Officer Trevor Bayley said the real point to emerge from the research is that recycled tyre oil can be used with diesel in a vehicle without further refining.

“The oil that comes from our process is a crude oil and the on-road tests show that it can be used in this way, as some critics have doubted its value,” he said.

“With further processing it can become the base for diesel, petrol, aviation fuel or any other petroleum-based product.”