Car Tires Suck

From the book, The World Without Us

To this day, nature hasn't come up with a microbe that eats it [a tire], either.  Goodyear's process, called vulcanization, ties long rubber polymer chains together with short strands of sulfur atoms, actually transforming them into a single giant molecule.  Once rubber is vulcanized -- meaning it's heated, spiled with sulfur, and poured into a mold, such as one shaped like a truck tire -- the resulting huge molecule takes that form and never relinquishes it.

Being a single molecule, a tire can't be melted down or turned into something else.  Unless physically shredded or worn down by 60,000 miles of friction, both entailing significant energy, it remains round.  Tires drive landfill operators crazy, because when buried, they encircle a doughnut-shaped air bubble that wants to rise.  Most garbage dumps no longer accept them, but for hundreds of years into the future, old tires will inexorably work their way to the surface of forgotten landfills, fill with rainwater, and begin breeding mosquitoes again.

In the United Sates, an average of one tire per citizen is discarded annually -- that's a third of a billion, just in one year.

Thanks to Mariginal Revolution. Yet more proof that gasoline/car taxes don't capture the true costs of automobile use. Of course in the comments section someone left this:

“In 2003, more than 290 million scrap tires were generated in the U.S. Nearly 100 million of these tires were recycled into new products and 130 million were reused as tire-derived fuel (TDF) in various industrial facilities. TDF is one of several viable alternatives to prevent newly generated scrap tires from inappropriate disposal in tire piles, and for reducing or eliminating existing tire stockpiles.”

See “Tire Derived Fuel” (http://www.epa.gov/garbage/tires/tdf.htm)

Properly run cement kilns work well with tires because the limestone absorbs the sulfur from the tires (forming gypsum, not CaS). Cement kilns also have high residence times (up to 10 seconds) and very high operating temperatures (up to 1500°C). Cement kilns aren’t perfect and exhaust gas treatment is still required (apparently).

See “Use of Cement Kilns in Managing Solid and Hazardous Wastes : Implementation in Australia” (http://ariic.library.unsw.edu.au/griffith/adt-QGU20050926-215906/). A useful quote

“The analysis of organic compound emissions indicated that extreme high combustion conditions in a cement kiln combined with high turbulence and long residence times readily overcome any oxygen deficiencies inside the kiln to achieve destruction efficiencies exceeding the 99.99% regulatory requirement and even reaching 99.9999% in many cases.”

See also “Cement Kiln” (http://en.wikipedia.org/wiki/Cement_kiln)

Comments

[Brown Bess]

Yeah, the tires just go poof.
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