“Plastic oil” could improve fuel
economy in cars, chemists say
Recycled plastic bottles could
one day be used to lubricate your car’s engine, according
to researchers at Chevron and the University of Kentucky, who
in laboratory experiments converted waste plastic into lubricating
oil. These polyethylene-derived oils, they say, could help improve
fuel economy and reduce the frequency of oil changes.
The pilot study appears in the
July 20 issue of the American Chemical Society’s peer-reviewed
journal Energy & Fuels. ACS is the world’s largest scientific
“This technology potentially
could have a significant environmental impact. It could make a
difference in communities that want to do something positive about
their waste plastic problem, especially if there is a refinery
nearby that could do all of the processing steps,” says
the study’s lead author Stephen J. Miller, Ph.D., a senior
consulting scientist and Chevron Fellow at Chevron Energy Technology
Company in Richmond, California.
Americans use about 25 million
tons of plastic each year. However, only about 1 million tons
of it is recycled, according to the Environmental Protection Agency.
The remainder ends up in landfills.
Some researchers have tried to
use recyclable plastic to produce fuels, but commercial interest
in this application has been limited. Most of this plastic is
polyethylene, which the Chevron and University of Kentucky researchers
showed can be broken down by heat into a wax that can be converted
into a high quality lubricating oil, Miller says.
Of the plastic used in the pilot
study, about 60 percent was converted into a wax with the right
molecular properties for further processing to make lubricating
oil for uses such as motor oil or transmission fluid. These high
quality oils derived from wax can assist auto manufacturers in
meeting mandated fuel economy specifications, Miller says.
The process for converting wax
to lubricating oil used in this pilot study was put into commercial
use by Chevron in the early 1990s with waxy petroleum-derived
sources. In the future, superior lubricating oils will be produced
from wax derived from a catalytic process known as Fischer-Tropsch,
which starts with natural gas, Miller says. This process will
be used commercially overseas, primarily in the Middle East, where
natural gas is less costly than in the U.S. In the U.S., production
of Fischer-Tropsch wax will likely be limited for a number of
However, this new study suggests
that using wax derived from recyclable plastic can produce lubricants
that are of equal quality compared to those derived from Fischer-Tropsch
wax, Miller says.