RECYCLING: Industry Explores Alternate Uses for Recycled Tires

David Davenport

Thirty percent of today's scrap tires can be re-used in alternate products, and the number is on the rise according to the Scrap Tire Council's Michael Blumenthal, Washington, D.C. The remaining 70 percent are stockpiled, not landfilled.

At least one person throws away one tire per year. That comes to more than 240 discarded tires annually. With mountains of tires forming, industries and research firms are discovering ways to re-use tire rubber.

Waste to energy is currently the largest market for scrap tires, specifically cement kilns and the pulp and paper industries. In addition, some utilities are using scrap tires as fuel and civil engineers (see chart) are developing ideas for scrap tires to replace virgin rubber.

Because the cement industry can use the entire tire, Blumenthal said it is considered to be the best fit for scrap tire energy. "No processing is necessary. It's cheaper than coal, and if you use whole tires, the cement kiln receives a tip fee," he said.

It is not as easy to turn tires into fuel for paper and pulp, said Blu-menthal. Tires have to be processed into one or two inch chips in order to fit into the feeding system. "Even so, they are cheaper than coal and do not impact emission," he said.

Major utilities can add 2 percent to their fuel stream by using tires and have no impact on their combustion process or emission. Large scale facilities are investigating tires to fuel, and if the trend continues, said Blumenthal, a significant number of large scale users could have a major impact on the scrap tire market.

The New York State Electric & Gas (NYSEG), Jennison Station, Bainbridge, N.Y., began testing tire chips and coal mixtures for fuel in 1991. In 1992, the facility started to use the mixture. The station is capable of burning 45,000 tons of tire chips annually using a blend of 25 percent tire chips with 75 percent coal. Although a blend of 50 percent tire chip and 50 percent coal is permitted, the facility uses between a 10 and 25 percent scrap tire blend, according to Alfonso Marcello, technical associate, NYSEG. "Since we've only been going since last October, we are still going through a learning curve to see what the optimum blend will be," he said.

The station, equipped with a tire chipper, accepts whole tires from local residents who pay a nominal drop-off fee to help offset chipping cost.

In 1992, NYSEG chipped a total of 160,155 tires and burned an equivalent of 320,393 tires. By June 1993, Jennison had burned the equivalent of one million tires.

The program, according to Mar-cello, has been very successful, and the public has been supportive. "Everyone realized that tires were an eyesore and a problem. It turned out to be a good interim solution to the scrap tire problem," he said.

Civil engineering applications use approximately 5 to 7 million tires per year and have strong opportunities for growth, said Blu-menthal. Applications such as artificial reefs and playground mats are currently in operation while other uses are still in the experimental stage. Future applications include tree root barriers to prevent sidewalk, road and building foundation damage; noise barriers; and railroad ties.

Civil engineering applications, said Blumenthal, present viable markets for scrap tires, but do not offer the same potential that the tire to fuel side offers. "But that's not to say it shouldn't be encouraged," he said.