Andy McIntosh made his way through a maze of garbage, undeterred in his search for a new energy source. After a 10-minute hike through the city dump, McIntosh found what he was looking for: thousands of discarded tires.
"When I see a tire, I see green," says McIntosh, speaking in both the environmental and monetary sense. He and his business partner, Vince Wong, are Canadians trying to make it in the business of tire pyrolysis, which recovers products from waste through incineration. Together, they hope to help the environment and make money by burning rubber.
"People treat tires as waste, but we treat them as raw material," says Wong, a chemical engineer. In industrialized countries, it’s estimated one tire per person is discarded each year, which, according to Environmental News Network, translates into more than 270 million tires thrown away annually in the United States. An estimated 500 million are stockpiled in the U.S., creating an eyesore and an environmental and health hazard. Tires can spontaneously combust, releasing toxins into the air, or become breeding grounds for mosquitoes and rodents. Wong believes tire pyrolysis can generate energy while cleaning up an old problem.
The average tire consists of 43 percent oil, 42 percent carbon black, eight percent steel and seven percent gas. Although there are 150 companies pursuing pyrolysis worldwide, very few have done it cost-effectively because the equipment and expertise needed is expensive.
In McIntosh and Wong’s affordable technique, the tires are shredded, then baked until they form gas under extreme heat in an airtight oven. The gases are vacuumed out, and when cooled separate into oil, methane and butane. Wong estimates this process will glean 7.7 pounds of energy-laden oil from a 20-pound tire. Pyrolysis oil can also be added to gasoline to increase its octane rating. The remaining butane and methane are recycled and reused to fuel the process.
The other byproducts are carbon black char and steel wire, which come out looking like burnt barbeque meat. The carbon can be used to make products from sneakers to vinyl siding, while the steel can be bundled and sold as scrap metal. Paul Williams, an energy researcher at the University of Leeds in England, points out that the main problem with pyrolysis is the lack of demand for its end product. Williams" research seeks to upgrade the carbon and oil to make them more marketable.
There is no doubting the technology’s potential. Juniper, a British waste management consultancy, estimates that waste pyrolysis could become a $9 billion industry by 2008. Other applications for scrap tires include recycling them into rubber products like floor mats, grinding them down for filler in industrial processes, and adding them to asphalt.