Dirty lubricating oil that comes out of car, truck or bus engines during oil changes could end up in your fuel tank, according to a study being conducted on both sides of the Atlantic.
A new process has been developed for recycling waste crankcase oil into gasoline-like fuel. Researchers claim it is the first to use microwaves and has “excellent potential” for commercial use.
“Transforming used motor oil into gasoline can help solve two problems at once,” said study leader, Howard Chase, professor of biochemical engineering at Cambridge University.
“It provides a new use for a waste material that’s too-often disposed of improperly, with harm to the environment. In addition, it provides a supplemental fuel source for an energy-hungry world.”
Estimates suggest that changing the oil in cars and trucks produces about 30billion litres (8billion gallons) of used motor oil each year across the globe.
In some countries a proportion of that dirty oil is collected and re-refined into new lubricating oil, or processed and burned in special furnaces to heat buildings.
Prof Chase noted, however, that such uses are far from ideal because of concerns over environmental pollution from re-refining oil and burning waste oil.
And in many other countries used automotive waste oil is discarded or burned in ways that can pollute the environment.
In response, scientists are looking for new uses for that lake of waste oil, which is growing significantly in volume as millions of people in China, India, and other developing countries acquire vehicles.
Among the most promising recycling techniques is pyrolysis, a process that involves heating oil at high temperatures in the absence of oxygen.
It breaks down waste oil into a mix of gases, liquids and a small amount of solids. The gases and liquids can then be chemically converted into petrol or diesel fuel. However, the current processes heat the oil unevenly, producing gases and liquids which cannot be converted easily into fuel.
Chase and his research team say the new method overcomes this problem and uses their new pyrolysis technology.
In lab studies, his doctoral students, Su Shiung Lam and Alan Russell, mixed samples of waste oil with a highly microwave-absorbent material and then heated the mixture with microwaves.
The pyrolysis process appears to be highly efficient, converting nearly 90% of a waste oil sample into fuel. So far, the scientists have used the process to produce a mixture of conventional petrol and diesel.
“Our results indicate that a microwave-heated process shows exceptional promise as a means for recycling problematic waste oil for use as fuel,” Lam and Russell said.
“The recovery of valuable oils using this process shows advantage over traditional processes for oil recycling, and suggests excellent potential for scaling the process to the commercial level.”
