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Environment

A New Source of Green Energy: Burning Tires?

If rubber recycling hits a glut, there may be little choice.

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Reuse and recycle. It’s a message that’s been hammered home; unfortunately, it isn’t always feasible. The automobile tire is the perfect example. Even hybrid cars need four of them apiece, and the global love affair with the automobile isn’t ending anytime soon. Worldwide, about a billion tires are sold annually, and eventually all get tossed. In the United States alone, we throw away 300 million tires a year—one for every man, woman, and child. These castoffs are a huge source of automotive-related pollution—the average used tire weighs 22.5 pounds and contains about two gallons of fuel, as well as other combustible carbon compounds. Dumped into huge stockpiles, tires harbor vermin, contribute to the spread of disease by creating mosquito breeding grounds, and feed huge fires: In August 1998, a grass fire ignited 7 million tires near the town of Tracy in California’s San Joaquin Valley, sending a plume of soot and noxious gas thousands of feet into the air. State authorities originally expected the fire to burn for about two weeks, but it endured for two and a half years. Cleanup was completed only in 2006, at a cost of $19 million.

Tires are so difficult to dispose of because they don’t easily become anything else. Up to now, any effort to recover the raw materials used to make tires has failed beause more fuel is needed to decompose the tire than is used in making a new one.

Engineers have been making some progress in dealing with this refuse, using old tires as raw ingredients for new construction mater­ials for roads and recreation facilities. But ironically, the best solution may be simply to use old tires to do what they do best: burn.

According to Michael Blumenthal, vice president of the environment and resource recovery group of the tire industry’s Rubber Manufacturers Association (RMA), 1992 was the first year that processors began to dip into the scrap tire inventory to convert it into new products, mixing crumb rubber and tire dust—ground-up rubber tires—with a urethane binder to make sidewalks, playground surfaces, and basketball courts. Many engineers now construct new roads using tire chips for backfill and insulation and to give asphalt added springiness and long­er life. Whole tires are used to build breakwaters, barriers, and berms. In Milpitas, California, engineers used 660,000 shredded tires as lightweight roadbed to support the Dixon Landing Road interchange on Interstate 880.

Because of innovations like these, figures from the RMA show the percentage of scrap tires that have been recycled in the United States is rising, from virtually zero in 1990 to 30 percent in 2005. The RMA’s counterpart across the Atlantic, the European Tyre & Rubber Manufacturers’ Association (ETRMA), recorded comparable achievements, with Europe recycling 27 percent of its scrap tires in 2004. This progress is helping make a dent in the stockpiles of old tires, at least in developed countries. In 1990 the United States had an estimated 1 billion old tires lying around. By 2005 (the most recent year for which statistics are available), the United States had slashed that figure to 188 million, thanks to both recycling and using tires as industrial fuel.

Vern Reum is one of the leaders in the effort to banish tires from the dumps and recycle them into productive use. Reum, president and owner of Tire Depot in Polson, Montana, has been in the scrap tire business for 18 years and now handles some 1.2 million of them per year. His company collects tires from Montana, Idaho, Washington, Oregon, and Wyoming, making most of its money by charging dealers for transporting the tires and for disposal—a per-tire assessment known as a tipping fee.

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