To develop the market for waste tires, the Board has
allocated $9.5 million in tire recycling grant funds since 1990. The Board
has provided funding for rubberized asphalt projects, crumb rubber as a
soil amendment in athletic fields, in playground mats, and other molded
rubber products and as a fuel supplement in cement kilns, and energy
facilities.
In 1999, approximately 31 million waste tires were generated in
California, approximately 2 million were imported from nearby states, and
slightly more than 20 million (64.5%) were diverted from disposal. The
remaining balance of waste tires is currently going to disposal, both
legal and illegal.
The following end markets for waste tires are discussed in more detail:
- Tires as a Fuel Supplement
- Retreading
- Value Added Rubber Products
- Civil Engineering
- Export of Waste Tires to Foreign
Markets
- Potential
Markets
1. Tires as a Fuel Supplement
Using tires as a fuel supplement in cement kilns and cogeneration
facilities constitutes the largest market for waste tires, both nationally
and in California. Of all waste tires generated in California in 1999,
38.8 percent were used as fuel. Tire Diverted Fuel (TDF) can be whole or
shredded tires used as a fuel. TDF is a very high quality fuel having
about 13,000 to 15,000 BTU per pound, (7,200 to 8,300 kcal/kg), about the
same as a superior quality coal. Most major boiler manufacturers have
developed the technology to efficiently burn shredded tires, but to date
they are not yet utilizing this resource in significant quantities.
Cement Kilns
In 1999, 4.1 million tires were used in three cement kilns in
California as a supplemental fuel. Tires are used in place of coal
because they have higher heat energy by weight and kilns can (in some
cases) charge a tipping fee of $.40 per tire that is lower than the
tipping fee at landfills. By using tires as fuel, cement kilns reduce
emissions of criteria air pollutants (pollutants for which emission
standards have been set) NOx and SOx (oxides of nitrogen and sulfur).
The steel belts in the tires offer a source of iron ore for the cement
making process.
Coal Cogeneration
Cogeneration is the process of simultaneously producing a heat
source and power in a single thermodynamic process. There are eight
plants in California operating as coal Cogeneration plants--Rio Bravo
Poso, Rio Bravo Jasmin and Mt. Poso in Bakersfield; Jackson Valley
Energy in Ione; Port of Stockton District Energy Facility, Air Products
Stockton, and Stockton Cogen in Stockton, and GWF Power System in
Hanford. Of these, the Stockton Cogen Plant is using shredded tires as a
supplement with the coal. Contact,Tom Heller, General Manager, at (209)
983-0391 for more information. Recently, the Port of Stockton District
Energy Facility and the Jackson Valley Energy Plant conducted emissions
tests funded by the Board. Each of these plants could use 1-2 million
tires per year.
Tire retreading is an established market for waste tires. Based upon
surveys of industry contacts, about 2.5 million retreaded tires were sold
in 1999. Most tire retreads are heavy truck tires, which use economically
competitive tires with new truck tires. Passenger tires are not designed
for retreading, thus diminishing this market for passenger tires.
One area that offers more diversion potential for waste tires is
through expanding crumb rubber markets. In 1999, an estimated 5.5 million
tires were diverted from disposal through crumb rubber applications. End
uses included rubberized asphalt, molded products, mats, playground
covers, speed bumps, and carpet pads. Recent technological improvements in
crumb rubber production allow smaller particle sizes, which have wider
applications in molded rubber and composite products.
Rubberized Asphalt Concrete (RAC)
The Rubberized Asphalt Concrete Technology Centers (RACTC) are
cooperative efforts with Los Angeles County and Sacramento County and
the CIWMB to promote the use of crumb rubber from scrap tires in roadway
rehabilitation projects. The RACTC offers services to local public
agencies throughout California at no charge. These include regional
workshops, on-site project assistance, problem solving, technical
assistance and a toll-free hotline. For more information in Los Angeles,
contact Lynn Nicholson at (888) 777-4775 and in Sacramento contact
Theron Roschen at (800) 373-1113. The RACTC also has a Web site at
www.rubberizedasphalt.org.
Rubber Products Manufacturers List
Tires can be used in the production of everything from porous
irrigation pipe to sound barriers. There are many manufacturers around the
United States turning used tires into valuable and marketable goods.
Please see our list of manufacturers at: www.ciwmb.ca.gov/RCP/.
Tires can be used in numerous structural and nonstructural
applications, such as alternative daily cover at landfills, lightweight
fill, fence construction, and retaining walls.
Alternative Daily Cover (ADC)
State requirements regarding ADC prescribe the quality, quantity, and
methodology employed in the application of daily cover at municipal solid
waste landfills. Specifically, 27 CCR § 20164 of defines daily cover
material as:
"…cover material placed on the entire surface of the active
face at least at the end of each operating day in order to control
vectors, fire, odor, blowing litter and scavenging."
The Board has approved the use of shredded tires as an ADC at municipal
solid waste landfills. The Board has also determined that this is an
approved diversion end use. This represents a potentially large market in
California because there are 190 landfills in the state. A large municipal
landfill may use up to 3 million tires per year in this application. The
two landfills in California using ADC are the Altamont Landfill in Alameda
County and the Chicago Grade Landfill in San Luis Obispo County.
Other civil engineering applications include:
Loose Fill. Shredded tires can be used as fill for low places and
trenches. A layer of topsoil would then be placed over. This allows
excess water to drain as well as acting as fill material.
Slope Stabilization. Shredded tires are used on inclines to
prevent sliding of the soil because of the tire material's lighter
weight compared with the surrounding soil. This reduces the risk of mud
and landslides.
Levee Slurry Walls. Tires can be chipped into 1-2 inch pieces and
added to a slurry mixture to form a levee cutoff wall. The mixture
hardens into a water impermeable levee. The California State University,
Chico, is testing this in a partnership with a private company. Contact Rovan
Younger at (530) 898-5216.
Landfill Leachate Collection Systems. Shredded tires are used as
a filter material in this process, which allows the leachate to drain
and be pumped elsewhere for treatment. The Yolo County landfill uses
this method to drain their local landfill. The leachate drains into a
sump pool and is pumped out to a wastewater treatment center.
Baled Tires. Baled tires have been used in several structural and
non-structural civil engineering applications such as retaining walls,
berms, and as fences. Tire bales have been successfully used as fill
material in a Gabion-style retaining wall in Humboldt County. The light
weight of the tire bales make them an attractive alternative to
conventional fill materials, such as pea gravel. When used in a fencing
or berm application, the bales are usually covered with stucco, gunite,
or dirt.
Tire export (consisting of both reusable and waste
tires) reduces the number of tires requiring eventual disposal in
California. According to industry contacts and staff estimates,
approximately 1.5 million tires were exported for reuse, retreading, and
crumb rubber production in 1999.
There is a potentially large market for waste tires through the
following technologies. These technologies need to be further developed to
make them more economically competitive.
Pyrolysis
There are currently few markets for the products of pyrolysis (oil,
gas, carbon black, and steel), principally because the revenue from the
sale of the products does not cover the cost of producing them.
Devulcanization
The major advantage to devulcanization is the ability to take old
tires and break them down into a feedstock that could be used to make
new tires and other rubber products. Tire manufacturers believe that new
tires may be manufactured with up to 10 percent recycled-content within
the next two to three years.
Gasification
Because of the high cost of production, there is currently no
commercially viable market for this product.
|
