Tests Continue on the `Slow Cook' Method of Recycling Used Plastic
But some environmentalists say the method is not really recycling
THE plastics industry hails it as advanced recycling. To some environmentalists, it is not recycling at all.
In a small processing plant here in western Washington, William Conrad is transforming plastics into three basic components: petroleum, carbon black, and gas. The process is called pyrolysis, the use of heat (1,300 degrees) to cause chemical decomposition. There is no need to clean or sort the plastic - any mix will do.
``I could take your clothes and run it through the system'' and come out with the ``same three things,'' says Mr. Conrad, president of Conrad Industries Inc. ``Pyrolysis is an old, old art.''
Dismayed at the dumping of valuable materials, Conrad has been recycling scrap tires here with this method since 1986. His push into plastics comes as Oregon moves ahead with a law requiring plastics to be recycled, reused, or made with recycled content starting in 1995.
The company plans to recycle 2 million pounds of plastic next year. The project is a partnership with the American Plastics Council, an industry group. But environmentalists question whether this should count as recycling. They acknowledge that pyrolysis is much better than incineration or landfill dumping. But some would rather see plastics recycled directly into new plastic products, as is typically done with paper, glass, and metal cans.
Jerry Powell, editor of Resource Recycling magazine of Portland, Ore., says Oregon's law should not give pyrolysis equal footing with other recycling methods when measuring recycling rates. ``It's not recycling; it's materials recovery,'' he says.
Oregon lawmakers are not the only ones wrangling over what recycling really is. ``This is a national issue,'' Mr. Powell says. He adds that it is the ``hottest'' policy debate at the National Recycling Coalition, a professional association of which he is chairman.
The thermal decomposition method appears to comply with common definitions of recycling. The federal Environmental Protection Agency, for example, has defined recycling as ``the process by which materials otherwise destined for disposal are collected, reprocessed or remanufactured, and reused.''
But Powell worries that the output from thermal decomposition will do little to reduce demand for virgin resins used in plastics manufacturing. Most of it will go to other uses, such as petroleum-based fuels. In the paper and aluminum industries, by contrast, recycling has significantly reduced demand for virgin pulp and bauxite. Pointing to the plastic industry's two success areas, soda bottles and milk jugs, Powell says plastics-to-plastics recycling can be done more economically than pyrolysis.
Despite this criticism, he praises pyrolysis as ``a great system'' for plastics that are contaminated or produced in volumes too small to be sorted cost-effectively.
Conrad himself takes a similar view: ``We can't and we don't want to disturb'' other economically viable plastics-recycling programs, he says.
Phil Bridges, vice president of Conrad Industries, says the company is targeting only plastic that would not otherwise find markets. ``As long as we're importing oil, I think this is a tremendous way to recycle,'' Mr. Bridges says.
When plastics are processed using thermal decomposition, the output is roughly 75 to 80 percent oil. Moreover, the company's tests suggest that this oil will be 40 to 50 percent monomers, the valuable building blocks of plastic. That is a much higher percentage of monomers than in crude oil.
The remaining output is mostly gas, which the company uses as fuel for the retorts into which plastics or tire chips are fed. The other output, a tiny fraction of carbon black, will be sold for industrial uses.
Because the plastics are cooked in an oxygen-free environment, nothing is burned, so for every pound of material that goes in a pound of material comes out.