Because of these problems, nearly every state has some form of scrap tire management regulations, including charges for tire disposal. Many states also offer financial incentives for using scrap tires in products. While these regulations generally increase tire disposal costs, which has led to an increase in illegal dumping in some areas, they have also increased the overall reuse and recycling of tires. In 1990, only about 11% of scrap tires were recycled. The Scrap Tire Management Council (see Organizations below) estimates that, in 1997, 270 million tires were scrapped, and about 75% (or 201.5 million) were recycled, including about 15 million that were exported. Of the remainder, 38.5 million were stockpiled, and 30 million were shredded and buried in mono (single material) landfills, or used as landfill cover.
We can all reduce the number of tires scrapped each year by maintaining proper tire pressure, rotation schedules, correct wheel balance and alignment, and by avoiding excessive acceleration and braking. These practices maximize tire life and performance, and also reduce vehicle fuel consumption and increase safety. Many people replace tires before it is actually necessary, doing so when another tire on the vehicle needs replacing. According to the U.S. Environmental Protection Agency (EPA), nearly 50% of tires are replaced after only half their potential life. Fortunately, tire dealers resell or reuse approximately 10 million used tires every year.
Many used tires can be retreaded for continued use. The Tire Retread Information Bureau estimates that in 1996, about 31.4 million retreaded tires were sold. Most were used by the trucking, aircraft, construction, and agriculture industries, and on U.S. government vehicles. Since retreading requires only one third of the crude oil used to make a new tire, this saved approximately 376 million gallons (1.44 billion liters) of oil. Eventually though, tires become unsafe for use on vehicles, and/or they cannot be retreaded. At that point, they can be recycled for use in new products and other purposes other than transportation, or converted to energy.
Nearly 15 million scrap tires are chopped, ground, or powdered for use in wide variety of products such as floor mats, adhesives, gaskets, shoe soles, and electrical insulators, or blended into asphalt for use in pavement binders and sealants, or as an aggregate substitute. Rubber modified asphalt (RMA) is reported to increase the durability and life of asphalt, but costs about twice as much as regular asphalt. Studies on the performance, health and safety effects, air emissions, and recyclability, and the development of mixing standards for RMA are underway. Positive results of these efforts are likely to increase the use of RMA.
Nearly 8 million scrap tires are cut, stamped, or punched into hundreds of different products every year. An additional 20 million whole or chopped scrap tires become fill and cover material in construction and landscaping, artificial reefs and breakwaters for beach erosion control, playground surfacing material and equipment, highway and race track crash and sound barriers, boat dock shock absorbers, and even materials for building houses. Farmers and ranchers use about 2.5 million whole scrap tires for holding down covers on hay stacks, controlling erosion, protecting structures from livestock damage, as rollers in corn husking equipment, and many other uses.
The use of scrap tires for fuel increases every year, and is currently the largest single use of scrap tires. Tire-to-energy technology preserves natural resources by utilizing the stored energy in petroleum-based tires. Tires have a heating value of 12,000 to 15,000 Btu per pound (6,668 to 8,335 kilocalories per kilogram). Each 20 pound (9 kilogram) car tire is equivalent to about 25 pounds (11.4 kilograms) of bituminous coal. Tires contain less ash than most types of coal and less sulfur than bituminous coals. Tires are burned whole or shredded into chunks as tire derived fuel (TDF). Burning whole tires saves shredding costs, but may increase the cost of transportation and storage. In 1997, cement kilns, pulp and paper mills, electric utilities, waste-to-energy plants, and industrial boilers burned approximately 140 million tires. Although some of these facilities use whole tires and/or TDF as the only fuel, most mix or "cofire" the tires/TDF with other fuels, such as coal. The TDF makes up about 10% of the total fuel mix.
Another potential technology for converting tires to fuel and other products is pyrolysis. Pyrolysis is the thermal distillation or decomposition of organic materials into oils, gases, and char. Pyrolysis has been proposed as a method to break down tires into salable products including steel, oil, gas, and carbon black. Despite many efforts to commercialize this technology, it is not yet economically viable in the United States. The products of tire pyrolysis have limited marketability, due to their comparatively low quality. Refining the products to market specifications requires expensive equipment. The capital investment and operating costs make the products too expensive to compete. Given current prices for crude oil and natural gas, tire pyrolysis has very limited potential.
There are numerous, ongoing efforts in various stages of development, to use the rubber in scrap tires to make new tires or other products. Michelin Tire Corporation developed a method to incorporate rubber from scrap tires to make up over 10% of the material to make a new tire. While this technology is still being tested, if commercialized it could result in the use of 30 million scrap tires every year.
Air Products and Chemicals, Inc., with financial assistance from the United States Department of Energy (DOE), developed a method for treating rubber from scrap tires. The method works by exposing the rubber to reactive gases that cause the surface of the rubber to become chemically active. It can then be bonded to other polymers. The resulting composite has many potential uses including non-pneumatic (solid) tires, carpet underlay, automotive seals and gaskets, caulks, sealants, and adhesives. The treated rubber requires much less energy to produce than the polymers it replaces. Each tire recycled with this process saves the equivalent of about 12 gallons (45.5 liters) of oil. The technology is being developed further to allow the rubber to be combined with a wide range of other materials such as polyvinyl chloride.
Pacific Northwest National Laboratory (PNNL) is developing a method to use thiophillic microorganisms to devulcanize (biodesulfurize) the surface of ground rubber particles, which will improve the bonding and adhesion of the ground tire rubber into the virgin tire rubber matrix. The microbial processing approach (see reference to reports below) may be applied to improve asphaltic materials and rubber and polymeric wastes to facilitate their recycling.
Publications
Chemi-Microbial Processing of Waste Tire Rubber: A Project Overview, R. Romine and L. Snowden-Swan, Pacific Northwest Laboratory, 1993. 13 pp. $19.50. NTIS Order No. DE94004781.
Development of Asphalts and Pavements Using Recycled Tire Rubber. Phase 1, Technical Feasibility. Technical Progress Report, September 1, 1994--August 31, 1995, J. Bullin, et al., Texas Transportation Institute, 1996. Available from NTIS (see Source List below), 142 pp., $31.00, NTIS Order No. DE97000259.
Markets for Scrap Tires, U.S. Environmental Protection Agency, Office of Solid Waste, 1991. Available from NTIS (see Source List below). 120 pp., $31.50, NTIS Order No. PB 92115252, Report No. EPA/530-SW-90-074A.
Microbial Processing of Waste Tire Rubber: FY-95 Annual Report, R. Romine and L. Snowden-Swan, Pacific Northwest National Laboratory (PNNL), 1995. For information on the status of this process, contact Lesley Snowden-Swan at (509) 372-4916.
Proceedings: 1991 Conference on Waste Tires as a Utility Fuel, Electric Power Research Institute (EPRI), San Jose, CA, January, 1991. Available from EPRI (see Source List below). 210 pp., $500.00, Report No. EPRI-GS-7538.
Recycled Rubber Products Catalog, Scrap Tire Management Council (see Organizations below), 1994. 22 pp., Free.
Recycling Tires, NTIS Published Search (Latest citations from Pollution Abstracts), NERAC, Inc., 1997. Available from NTIS (see Source List below). 10 pp., $65.00, NTIS Order No. PB-97-853360. This bibliography contains up to 250 citations on scrap tire recycling.
Scrap Tire Recycling: Promising High Value Applications, Final Report, B. Bauman, P. Leskovyansky, and H. Drela, Air Products and Chemicals, Inc., for United States Department of Energy, 1993. Available from NTIS (see Source list below). 64 pp., $21.50, NTIS Order No. DE94008166.
Scrap Tire Technology and Markets, C. Clark, K. Meardon, and D. Russell, Pacific Environmental Services, for U.S. Environmental Protection Agency, Noyes Publications, 1993. Available from Noyes Data Corporation, 369 Fairview Avenue, Westwood, NJ 07675, (201) 666-2121. 316 pp., $54.00, ISBN No. 0-8155-13178.
Scrap Tire Terminology, Tire and Rubber Recycling Advisory Council (TRRAC), 1996. Available from TRRAC (see Organizations, below), 27 pp., $10.00.
Scrap Tire Use/Disposal Study 1997 Update, J. Serumgard and M. Blumenthal, Scrap Tire Management Council (see Organizations below), 1998. 55 pp., $25.00.
State Scrap Tire Management Programs: 1999 Legislative, Regulatory, and Market Development Review, Recycling Research Institute (RRI), 1996. Available from RRI (see Organizations below). 36 pp., $29.00
Summary of Markets for Scrap Tires, U.S. Environmental Protection Agency, Office of Solid Waste, 1991. Available from RCRA Information Center (see Organizations below). 12 pp., Free, Report No. EPA/530-SW-90-074B.
Tire-Derived Fuel Cofiring in a Test Pulverized Coal Utility Boiler: Final Report, A. Joensen, Electric Power Research Institute (EPRI), 1994. Available from EPRI (see Source List below). 55 pp., $3,750.00, Document No. TR103851.
1999 Scrap Tire and Rubber Users Directory, Recycling Research Institute (RRI), 1997. Available from RRI (see Organizations below). 160 pp., $49.00.
Articles
"A Finer Grind for Rubber Recyclers," D. Riggle, BioCycle, (36:3) p. 42, March 1995.
"All Tired Out: Tire Fires Hinder Efforts to Breathe Easy," B. Donahue, E Magazine, (1:6) p. 23, November/December 1990.
"Funding Innovative Uses for Scrap Tires," Ed., BioCycle, (40:3) pp. 61-63, March 1999.
"Good Year for Tire Recovery," M.F., BioCycle, (37:3) pp. 35-37, March 1996.
"Improving Scrap Tire Processing," C. Astafan, Solid Waste Technologies, (11:1) pp.13-14, 18, January/February 1997.
"Innovative Uses for Whole Tires," K. Gray, BioCycle, (39:9) pp. 53-55, September 1998.
"Puncturing the Scrap Tire Problem," R. Steuteville, BioCycle, (36:10) pp. 51-52, October 1995.
"Pushing the Scrap Tire Envelope," R. Steuteville, BioCycle, (37:10) pp. 30-32, October 1996.
"Reprocessing of Used Tires into Activated Carbon and Other Products," H.Teng, et al., Industrial and Engineering Chemistry Research, (34:9) pp. 3102-11, September 1995.
"Reactive Coprocessing of Scrap Tires and Heavy Oil," S. Saraf, et al., Resources Conservation and Recycling, (13:1) pp. 1-13, April 1, 1995.
"Scrap Tires: STATEing the Facts," M. Dabaie, Waste Age, (25:10) pp. 62-71, October 1994.
"Scrap Tire Market Analysis," M. Blumenthal, BioCycle, (38:2) pp. 70-72, February 1997.
"Shredded Tire Market Options," K. Gray, BioCycle, (39:10) pp. 52-53, October 1998.
"Tapping the Tire Pile," L. Lamare, EPRI Journal, (20:5) pp. 28-34, September/October 1995.
"Tires-To-Energy Plant Takes Highroad in Managing Discharges," J. Makansi, Power, (136:4) pp. 152-56, April 1992.
"Turning Discarded Tires into Basic Tire Chemicals," Ed., Solid Waste Technologies, (12:2) p. 12, March/April 1998.
Source List
Electric Power Research Institute (EPRI)
Distribution Center
207
Coggins Drive
Pleasant Hill, CA 94523
Phone: (925) 934-4212; Fax: (925)
944-0510
World Wide Web: http://www.epri.com/
EPRI adds charges for
shipping and handling. Check price and availability of documents before
ordering.
National Technical Information Service (NTIS)
5285 Port Royal
Road
Springfield, VA 22161
Phone: (800) 553-6847 or (703) 605-6000; Fax:
(703) 605-6900
Email: orders@ntis.fedworld.gov; World Wide
Web: http://www.ntis.gov/
Organizations
American Portland Cement Alliance (APCA)
1225 Eye Street, NW
Suite
300
Washington, DC 20005
Phone: (202) 408-9494
The APCA can supply
information on the use of tires for fueling cement kilns.
Earthship Global Operations
P.O. Box 104
Taos, NM 87571
Phone: (505)
751-0462; Fax: (505) 751-1005
Email: biotecture@earthship.org; World Wide
Web: http://www.earthship.org/
For
information on building homes using scrap tires as the material for walls,
contact Earthship.
National Tire Dealers and Retreaders Association (NTDRA)
11921 Freedom
Drive
Suite 550
Reston,VA 20190
Phone: (800) 87-NTDRA
NTDRA
provides information on the tire industry, retreading, and scrap tire
management.
Recycling Research Institute (RRI)
133 Mountain Road
P.O. Box
714
Suffield, CT 06078
Phone: (860) 668-5422
Publication Orders and
Subscriptions
P.O. Box 2221
Merrifield, VA 22116
Phone: (703)
280-9112
RRI publishes several publications on scrap tire markets including a
monthly newsletter, Scrap Tire News, that covers developments in the tire
recycling industry. An annual subscription is $118.00.
Resource Conservation and Recovery Act (RCRA) Information Center
U.S.
Environmental Protection Agency/Office of Solid Waste (OS-305)
1725 Jefferson
Davis Highway
Suite 1200-A
Arlington, VA 22202
Phone: (703) 412-9810 or
(800) 424-9346; Fax: 703-412-3333
World Wide Web: www.epa.gov/epaoswer/hotline/index.htm
Scrap Tire Management Council (STMC)
1400 K Street, NW
Suite
900
Washington, DC 20005
Phone: (202) 682-4880
STMC has various
publications and briefing sheets on many aspects of scrap tire management and
recycling alternatives. They also publish a free quarterly newsletter, Scrap
Tire Connection.
Tire Retread Information Bureau (TRIB)
900 Weldon Grove
Pacific Grove,
CA 93950
Phone: (408) 372-1917; Fax: (408) 372-9210
Email: retreads@aol.com
TRIB is a nonprofit,
industry supported association dedicated to the recycling of tires through tire
retreading and repairing. An information package is available on request.
Tire and Rubber Recycling Advisory Council (TRRAC)
c/o International Tire
and Rubber Association, Inc. (ITRA)
P.O. Box 37203
Louisville, KY
40233-7203
Phone: (800) 426-8835 or (502) 968-8900; Fax: (502)
964-7859
Email: itra@itra.com; World Wide
Web: http://www.itra.com/
Your interest in energy efficiency and renewable energy is greatly appreciated. If we can be of further assistance, please feel free to contact us again.
EREC is operated by NCI Information Systems, Inc. for the National Renewable Energy Laboratory/U.S. Department of Energy. The statements contained herein are based on information known to EREC at the time of printing. No recommendations or endorsement of any product or service is implied if mentioned by EREC.
Energy Efficiency and Renewable Energy Clearinghouse (EREC)
P.O. Box 3048
Merrifield, VA 22116
Voice: 1-800-DOE-EREC
e-mail: doe.erec@nciinc.com