Business Technology; Turning Waste Plastics into Fuels

By JOHN HOLUSHAAUG. 28, 1991 This is a digitized version of an article from The Times's print archive, before the start of online publication in 1996. To preserve these articles as they originally appeared, The Times does not alter, edit or update them. Occasionally the digitization process introduces transcription errors or other problems. Please send reports of such problems to . As complex plastics increasingly replace metals in cars and appliances, recycling these products becomes a larger problem. Attention is now turning to a high-temperature process called pyrolysis that breaks down plastics into burnable oil and gas.Auto makers and plastic suppliers hope to demonstrate within a few years that this technique has great commercial potential. Environmental advocates question whether pyrolysis is truly recycling, but backers of the technique say it is far better than throwing the plastic away.Pyrolysis breaks materials down by heating them at high temperatures in the absence of air. Because no oxygen is present, plastics and rubber left over from cars do not burn, as they would in an incinerator. Instead, the heat, about 1,300 degrees Fahrenheit, breaks the complex hydrocarbons down into simpler molecules, producing a liquid resembling heating oil and a combustible gas, along with some ash. Potential for PollutionBecause nothing except the fuel for the pyrolysis reactor is burned, the technique may cause less air pollution than incinerators. But if the gas produced by pyrolysis is used to heat the reactor once it reaches operating temperature, as most plans envision, pollution will result from plastic and rubber that contain chlorine or sulfur, said Raymond Machacek, of A. D. Little, a consulting firm.AdvertisementVinyl plastics contain chlorine, and sulfur is used in the vulcanization of rubber. The chlorine and sulfur atoms tend to form hydrochloric and sulfuric acids, which are toxic pollutants, Mr. Machacek said.AdvertisementThe growing amount of plastic in automobiles causes grumbling among metal recyclers, because it results in more worthless material that must be disposed of in landfills, at additional cost. Unlike plastic soda bottles, which can easily be reprocessed, most of the plastics left after cars are shredded and the metals extracted are composites of materials that have been further contaminated by paint and adhesives."Very often you will have incompatible plastics glued together," said Richard L. Klimisch, an environmental specialist at the General Motors Corporation's Technical Center here. In addition, many of the plastics are a type known as thermosets, which cannot be melted down and used again, like the material in soda bottles.A car on exhibit at the technical center, cut away to display new sound-deadening insulation materials, also inadvertently illustrates how difficult these new materials might be to recycle. Several of the insulating materials are simply labeled, "Complex blend of various stuff."Researchers at the G.M. Technical Center are running perhaps the largest pyrolysis trials, but an association that includes several major plastic and rubber makers, including Goodyear Tire and Rubber, Dow Chemical, Eagle-Picher, Allied-Signal and Owens-Corning Fiberglas, is also experimenting with the technique.Industry trends make it clear that metal recyclers are going to have to find ways to cope with more plastic. "Cost is driving the industry to greater use of plastic," said Irvin E. Poston, a plastics specialist at G.M.He notes that plastic body parts are lighter than steel, requiring less costly tooling to shape and improving fuel economy. The entire outer body of G.M.'s new line of mini-vans, like the Chevrolet Lumina APV, is made of composite plastic. Pyrolysis recovers the energy content of plastic after its useful life is finished, he said.Please verify you're not a robot by clicking the box.Invalid email address. Please re-enter.You must select a newsletter to subscribe to.View all New York Times newsletters.Plastics suppliers say they may be able to use the ash produced in pyrolysis as well, particularly if the feedstock is uncontaminated scrap from the production process. Since some of the composites used in auto body panels consist of 50 percent inert filler, clean ash might be substituted for the limestone used now. But it is less likely that ash from shredder residue contaminated with other substances could be used.Industry officials have been quick to label pyrolysis a form of recycling, but some environmentalists say it is similar to incineration, because the material is destroyed and some energy is used. "We do not consider incineration as recycling on this side of the environmental fence, and a lot of people put pyrolysis in the same category," said Lisa Collaton, a solid-waste specialist at the Environmental Action Foundation in Washington.AdvertisementAdded John Ruston of the Environmental Defense Fund in New York, "Pyrolysis is not recycling; it is pyrolysis."Mr. Poston said G.M. and some plastic suppliers had run pyrolysis tests on shredder residue at two operations for processing old tires. He said that once the material reached operating temperature, it gave off enough gas to be self-sustaining without external fuel. The recovered oil is available for sale.He said the company and its suppliers planned larger-scale tests to see if the approach was technically and economically feasible in commercial quantities. "We have done 5,000 pounds; now we are going to do a run of 50,000 pounds so we can see the true economics," Mr. Poston said. More Plastic in CarsA group of plastic parts suppliers predicts that the amount of thermoset materials going into cars will almost double by 1995, to 423 million pounds, from 242 million pounds in 1990. That is in addition to thermoplastic materials, which can be melted and used again.Officials involved in recycling say pyrolysis may have a place in materials disposal, after more valuable plastic parts of old cars and appliances have been pulled out for recycling. "Pyrolysis can be part of the waste-management approach, but we should not give up on recovering various plastic streams for re-use," said Michael Fisher, a technical director at the Council for Solid Waste Solutions, a plastics industry group.Noting that it took metal recyclers several decades to refine techniques for separating different metals and alloys, he said that the plastics industry was just beginning the process. "There are 20 different types of plastic on an automobile," he said. "Some will be recycled, and some will go for pyrolysis."Herschel Cutler, executive director of the Institute for Scrap Recycling Industries, said the institute was interested in pyrolysis, despite economic, technical and pollution problems with some other experiments. "There have been some plants in the past that were dismal failures," he said.Nevertheless, he said, with the amount of plastic in cars rising, "we are still looking at it." He added, "We may see a new generation of pyrolytic activity that really can convert materials to oil, gas and carbon black."A version of this article appears in print on August 28, 1991, on Page D00009 of the National edition with the headline: . Order Reprints| Today's Paper|Subscribe