So, you’ve decided to get rid of an old car for a fuel-efficient model as part of the Cash for Clunkers program. Not only does your new ride have a better carbon footprint, but the old one will be shredded and recycled. It’s a win-win situation.
That is, unless you consider that recycling cars sends between 3 and 4.5 million tons of shredder residue to landfills every year. This material includes everything from plastic to glass to rubber and can represent as much as 25 percent of the weight of a car that is not recycled.
Why can’t the rest of this material be recycled? It actually can be, and a partnership between the American Chemistry Council, Argonne National Laboratory and USCAR has been working on a way of extracting more of this material, specifically the plastic.
What is Fluff?
When a car is shredded, a separate process removes the metals, including aluminum and steel. The same process occurs when recycling appliances or building materials, since shredding is a less expensive process than de-manufacturing. The leftover material is shredder residue, also known as “fluff.” This can even include some metal that is too small to detect.
Since the average car is 65 percent steel, much of the material will be recycled. But consider just the plastic components of a car that will end up as shredder residue:
- Hard plastics such as bumpers and dashboards
- Plastics used for safety, including airbags and seat belts
- Carpeting fabric, typically nylon
Landfills often use shredder residue as daily cover, which reduces odors and the chance that garbage will blow away. It can also be burned as fuel since plastic is made of petroleum. So while there is a practical use for fluff, the materials can also be reprocessed into new materials.
The research into recovery of shredder residue has been ongoing for more than 15 years under a series of Cooperative Research and Development Agreements (CRADA) between both the public and private sectors. The participants include:
- The Plastics Division of the American Chemistry Council – The Automotive Group of the Plastics Division is focused on demonstrating that plastics and plastic composites are the responsible and sustainable choice over the vehicle life cycle. ACC promotes the benefits of plastic components that are safe, light-weight for fuel efficiency and cost-effective.
- Argonne National Laboratory – One of the U.S. Department of Energy’s largest research centers, Argonne’s mechanical separation pilot plant in Illinois is able to take shredder residue through a physical separation process and plastics recovery process to extract specific polymers.
- The Vehicle Recycling Partnership (VRP) of the United States Council for Automotive Research (USCAR) – Members are the three American auto manufacturers, DaimlerChrysler Corp., Ford Motor Corp., and General Motors Corp.
The CRADA was designed to leverage activities of the industry and DOE, according to Jim Kolb, senior director of Automotive for the American Chemistry Council. The goal is to advance technology for the sustainable recycling of all materials including plastics, plastic composites and foam plastics used in automotive vehicles.
To do that, one has to deal with all of the various materials produced by the shredding process. The key issue is justifying the cost of additional material recovery with savings in landfill tipping fees and revenue from the creation of usable recycled plastics.
“Plastics are too valuable to go into a waste stream and should be recycled,” says Kolb. “Natural gas and oil used as feedstock for automotive plastics are a much better environmental use than burning them once as fuel for transportation purposes.”
How Does It Work?
The recovery of plastic from shredder residue involves identification and separation. Compatibility is an issue because different polymers of plastic cannot be recycled together.
After plastic is separated from other components of the shredder residue, Argonne is able to separate polymers using a flotation system, as some will float and others will sink. This process is able to recover 95 percent of the plastic from a shredded auto, which Argonne has been able to reprocess into products such as battery trays and steering-column components.
The key issue is justifying the cost of the process with savings in landfill tipping fees and the creation of new products.
“If shredders see there is money to be had with materials other than metals, then it will happen,” says Kolb. “We’re researching how to help them help themselves.”
Even if auto plastics are recycled, certain parts of the car will end up in a landfill. But Argonne estimates that recycling just the plastic and metal would represent 24 million barrels of oil saved each year.