Materials Characterization Paper 

In Support of the 

Proposed Rulemaking: 

Identification of Nonhazardous Secondary Materials That Are Solid Waste 

Auto Shredder Residue 

March 18, 2010 

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1. Definition of Auto Shredder Residue 

Auto shredder residue (ASR) is the 15 to 20 percent of vehicle materials remaining after a 

vehicle has been shredded and removed of reusable parts and metals. ASR is composed of 

plastics, rubber, foam, residual metal pieces, paper, fabric, glass, sand, and dirt (EPA, 2008; 

USCAR, 2008). It is also termed “auto fluff” or “auto shredder fluff.” 

2. Annual Quantities of Auto Shredder Residue Generated and Used 

(1) Sectors that generate auto shredder residue

Auto shredding operations, categorized under NAICS 423930 (Recyclable 

Material Merchant Wholesalers) are the only known generators of ASR. There 

are approximately 185 to 200 auto shredders in the U.S. (Boughton, 2006; 

DeGaspari, 1999). 

(2) Quantities of auto shredder residue generated 

The U.S. generates approximately 5 million tons of ASR annually and nearly all 

of this is landfilled (Hook, 2008; EPA, 2008). 

(3) Trends in generation of auto shredder residue 

Quantities of ASR produced are likely to increase in the future, due to the 

growing number of cars scrapped each year and the increased use of plastics in 

automobile production (Nourreddine, 2007). 

3. Uses of Auto Shredder Residue 

(1) Combustion uses of auto shredder residue 

Currently, nearly all ASR is landfilled and a small portion is incinerated, 

primarily owing to the lack of cost-effective technology to process and use ASR 

(Argonne, 2003). An additional barrier to using it as fuel is that unprocessed ASR 

has high ash, heavy metal, and chlorine content (Boughton, 2006). 

Approximately 20 to 50 percent of dry ASR is combustible, including plastics, 

fabric, and rubber; incombustibles include metals, glass, dirt, and ash. The first 

step in processing ASR for fuel use would be removal of incombustibles (Tai, 

2006; Boughton, 2006). 
Auto Shredder Residue 

ASR could potentially be used as a supplement to conventional fuel in cement 

kilns or steel mill blast furnaces. Use of ASR in cement kilns may be more easily 

accomplished than in boilers and other combustion units because kilns can 

tolerate high ash content and heterogeneous materials. A recent evaluation of 

ASR use in cement kilns conducted by the California Department of Toxic 

Substances Control suggests that, despite the obstacles of separating combustibles 

from incombustibles and reducing contaminant concentrations, processing ASR 

for use in cement kilns would be cost-effective, due largely to the avoided 

transportation costs and tipping fees associated with landfilling (Boughton, 2006). 

This effect, however, would vary throughout the U.S. due to regional differences 

in transportation distances and landfill tipping fees. In addition, the Environment 

and Plastics Industry Council and the American Plastics Council have conducted 

research investigating methods to process ASR into a more suitable fuel for steel 

mill blast furnaces (Cirko, 1999). 

(2) Non-combustion uses of auto shredder residue

As mentioned above, nearly all ASR is landfilled, and it appears that virtually no 

ASR is currently beneficially used. 40 CFR 761.62, “Disposal of PCB bulk 

product waste,” states, however, that ASR may be disposed in landfills as daily 

cover or used under asphalt as part of road bed, but no data on such applications 

have been identified. In addition, other potentially recoverable materials 

contained in ASR and their potential uses include: 

• Foam, which accounts for 5 percent of vehicles by weight but 30 percent 

by volume, can be rebounded and used as carpet padding and seat cushions 

in cars (DeGaspari, 1999). 

• Plastics, which account for 30 percent of vehicle weight, can be recycled 

into battery trays (Hook, 2008). 

• Iron oxide residuals can be used as an ingredient in cement production 

(Argonne, 2003). 

(3) Quantity of auto shredder residue landfilled

Sources generally state that most, if not all, ASR is landfilled (Hook, 2008; EPA, 

2008; Boughton, 2006). This would suggest that approximately 5 million tons of 

ASR are landfilled annually. 

4. Management and Combustion Processes 

(1) Types of units using auto shredder residue

Currently most ASR is landfilled, though development of methods to use ASR is 

underway. Potential users of ASR include: 

• Cement kilns 

• Steel mill blast furnaces 

• Car manufacturers 

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Auto Shredder Residue 

(2) Sourcing of auto shredder residue

Approximately 12 to 15 million automobiles are disposed of annually in the U.S. 

(USCAR, 2008). Once automobiles reach the end of their useful life, they are 

sent to one of roughly 12,000 auto dismantlers, where the car is stripped of 

reusable parts. The stripped cars are then sent to one of approximately 185 to 200 

auto shredding operations, where hammermills crush them into smaller pieces. 

Metal chunks are recovered and sold to metal scrap processing industries 

(DeGaspari, 1999). Over 25 million tons of materials are recovered for reuse or 

recycling. The remaining material comprises the ASR (EPA, 2008). 

(3) Processing of ASR for combustion uses

Unprocessed ASR has poor fuel characteristics, due to its high ash content; the 

presence of contaminants, including heavy metals, chlorine, and PCBs; and the 

heterogeneity of ASR, which is made up of approximately 20 to 50 percent 

incombustibles (Tai et al, 2006; Boughton, 2006). Prior to use as a fuel, ASR 

would therefore require significant separation and processing to isolate 

combustible materials with low ash content and low contaminant concentrations. 

The California Department of Toxic Substances Control has developed methods 

for separating and beneficiating the ASR stream to make it suitable fuel for 

cement kilns. First, trommels are used to create ASR sub-streams of different 

sizes, which also results in some rough separation by material (e.g., residual metal 

fines are small, while plastic and rubber pieces are larger). Then further 

separation is performed by hand and through density separation techniques, with 

the goal of developing a mixture of ASR that maximizes energy content, while 

minimizing content of ash, chlorine, and heavy metals. This process achieves a 

mixture of ASR that represents 30 percent of the original mixture and has a 

heating value of approximately 13,240 Btu per pound, which is higher than that of 

most types of coal (Boughton, 2006). 

The Environment and Plastics Industry Council and the American Plastics 

Council coordinated with eight automobile shredders to develop a procedure for 

processing ASR for use in steel mill blast furnaces. This process, which would 

reduce the ash content of ASR and increase its energy content, would yield an 

ASR material with a thermal value of approximately 10,000 Btu per pound 

(Cirko, 1999). 

Researchers in Taiwan have taken further steps in the development of ASR for 

fuel use by processing it into ASR-derived fuel (ASRDF) rods, for ease of 

transportation and storage. The first step in this process is the manual removal of 

glass, electrical wires, dirt and gravel, and metal components, yielding an ASR 

mixture with a heat value of approximately 10,500 Btu/pound. Then the ASR is 

placed into an extrusion apparatus, where it is exposed to high pressure and 

temperature and formed into rods. The extrusion process reduces the heat value 

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Auto Shredder Residue 

by approximately 1,800 Btu/pound, but the rods have a higher heat per unit of 

mass than does the un-compacted material (Tai et al, 2006). 

(4) Processing of ASR for non-combustion uses 

As indicated above, virtually no ASR is used for non-combustion applications 

because of the heterogeneity of ASR material. The Department of Energy’s 

Argonne National Laboratory, however, has recently developed methods for 

separation, recovery, and use of ASR. After undergoing separation and cleaning 

processes, certain constituent materials of ASR can be recovered. Argonne has 

found that up to 60 percent of ASR can be recovered as usable material (Hook, 

2008). 

The process developed by Argonne begins with bulk separation through use of a 

two-part trommel, which separates ASR into three streams: a polymersconcentrated stream (45 percent of ASR, by weight), foam (10 percent), and small 

inorganic particles (45 percent). The first part of the trommel is equipped with a 

fine mesh, through which the inorganic particles are separated. The second part 

of the trommel has larger slots, through which plastics and rubber pieces fall, 

leaving behind the foam. Each of these three streams is then further processed to 

extract the useful materials. The polymers undergo density separation and frothflotation to be separated by type, in order to recover those plastics and rubbers 

that are present in the largest volumes or that have the highest value. The foam, 

which contains automotive fluids and some residual inorganic particles, is run 

through a series of stages for cleaning, and is then dried and baled. The inorganic 

particles, which include metal residuals, dirt, and glass, are exposed to magnets to 

extract iron oxides, and the rest is discarded (Argonne, 2003; DeGaspari, 1999) 

At present, Argonne’s system is not yet used in the United States, though it has 

been licensed to Salyp N.V., a recycler in Belgium, which completed construction 

of an ASR recycling plant in 2003 (DeGaspari, 1999; Hook, 2008). 

(5) State regulatory status of auto shredder residue beneficial use

According to state responses to a 2006 survey by the Association of State and 

Territorial Solid Waste Management Officials (ASTSWMO), Florida has 

approved ASR as landfill initial cover, while Kentucky, Maryland, Massachusetts, 

Michigan, New Hampshire, New York, Tennessee, Virginia, and Wisconsin have 

approved it as an alternate daily landfill cover. ASTSWMO also reports that 

Michigan and Texas have approved ASR for liquid solidification. Wisconsin has 

pre-approved ASR for landfilling and Washington has pre-approved ASR in a few 

cases as alternative daily cover (ASTSWMO, 2007). 

5. Commodity Composition and Impacts 

(1) Composition and energy content of auto shredder residue

(a) Composition: 

 30 percent polymers (by weight) 

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Auto Shredder Residue 

 10 percent residual metals 

 5 percent foam 

 The remainder is a mixture of glass, wood, paper, sand, dirt, rocks, and 

automotive fluids (Hook, 2008; DeGaspari, 1999) 

 (b) Energy content: 

 Unprocessed ASR – roughly 5,000 Btu/pound (Boughton, 2006) 

 After removal of incombustibles – 9,000-10,500 Btu/pound (Tai et al, 

2006; Cirko, 1999) 

 After removal of incombustibles and additional processing to isolate 

combustibles with high energy content - 13,240 Btu/pound (Boughton, 

2006) 

(2) Impacts of auto shredder residue use

a. Cost impacts 

The recycling and use of ASR may result in cost savings. The California 

Department of Toxic Substances Control conducted an economic analysis of ASR 

use in cement kilns, and found that the processing and use of all annuallygenerated ASR for cement kilns would save the cement manufacturing industry 

$50 million per year through reduced energy costs. It would also save auto 

shredding operations $20 million per year in avoided landfilling costs. While the 

costs of processing the ASR for use in cement kilns would also amount to $20 

million per year, auto shredding operations could also generate $20 million per 

year in revenue from the sale of copper, which is extracted during processing 

(Boughton, 2006). Alternatively, if all ASR were to be used as a fuel in steel mill 

blast furnaces, it could reduce fuel costs for operators by as much as $20 per ton 

of coke replaced (Cirko, 1999).1 

Regarding the use of ASR for non-fuel applications, savings could be achieved 

through avoided production of virgin foam. While clean recycled foam sells for 

$0.25 to $0.30 per pound, virgin foam costs approximately $1 per pound 

(Argonne, “Recovering Foam from Scrapped Autos”). In addition, the savings 

referenced above with respect to copper recovered from ASR prior to its use as a 

fuel would presumably apply to beneficial use for non-fuel applications as well. 

Savings could also be realized through the re-use of other materials contained in 

ASR, but no information on these savings has been identified. 

b. Environmental impacts 

Comprehensive data on the environmental impacts of using ASR as a substitute 

for virgin materials have not been identified. Available data sources, however, 

contain the following information regarding these impacts: 

 1 The figures presented in this paragraph could change over time, owing to variations in virgin fuel prices, 

landfilling costs, and the value of copper. The California Department of Toxic Substances Control assumed the 

following prices and values: a price of $50/ton of coal, landfilling tipping fee of $17/ton, trucking cost of $2/mile, 

average distance to landfill of 20 miles, and $0.85/pound value of scrap copper wiring. 

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Auto Shredder Residue 

• Argonne estimates that the recovery and reuse of polymers and residual 

metals, for non-fuel applications, from all of the ASR produced annually in 

the United States would save the equivalent of 24 million barrels of oil per 

year and reduce CO2 emissions by 12 million tons (Hook, 2008).2

• Benefits from the use of ASR as a fuel may also include reduced CO2

emissions from substitution for coal (Boughton, 2006). The California 

Department of Toxic Substances Control estimates that if all ASR produced 

in the United States were processed for use in cement kilns, it could 

potentially provide 6 percent of the cement industry’s energy needs and 

result in the conservation of approximately one million tons of coal 

annually. 

• Additionally, diverting ASR from landfills prevents potential leachate 

contaminated with ASR constituents (Boughton, 2006). 

It is important to note that the presence of contaminants in ASR raises concerns 

about emissions from the combustion of this material. The California Department 

of Toxic Substances Control found that, while its processing techniques for 

developing ASR as a fuel for cement kilns minimizes contaminant concentrations, 

chlorine and heavy metals still remain at levels that may limit the rate at which 

ASR may be fed into a cement kiln (Boughton, 2006). Additionally, although 

ASRDF rods have low heavy metals concentrations, the chlorine content of these 

rods may represent a potential hazard (Tai et al, 2006).3

 Additional efforts to 

eliminate PVC from ASR prior to its combustion for fuel purposes may mitigate 

chlorine-related contamination issues, given that PVC is typically 50 percent 

chlorine (Boughton, 2006). 

 2

 It is unclear whether these figures represent estimates of direct or lifecycle energy and emissions impacts. 

In addition, it is unclear whether this CO2 emissions value is net of the emissions associated with burning ASR. 

3 In the Taiwanese study, no efforts were taken to remove combustibles with high chlorine contents, so 

chlorine contamination is more of a concern than in the California study. Yet, in the Taiwanese study, metals were 

removed more thoroughly by hand, so the rods present less of a threat of metal concentrations.

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Auto Shredder Residue 

References 

Argonne. 2003. “Materials Recovery from Auto Shredder Residue.” 

<http://www.es.anl.gov/Energy_systems/Process_Engineering/Technologies/Documents/

3-ASR_2003.pdf>. 

Argonne. “Recovering Foam from Scrapped Autos.” Argonne National Laboratory 

<http://www.anl.gov/techtransfer/Available_Technologies/Environmental_Research/auto

shredder.html>. 

Association of State and Territorial Solid Waste Management Officials (ASTSWMO). 2007, 

2006 Beneficial Use Study Report, published by Association of State and Territorial Solid 

Waste Management Officials. 

Boughton, Robert. 2006. “Evaluation of shredder residue as cement manufacturing feedstock.” 

California Department of Toxic Substances Control. 

Cirko, Cathy. 1999. “Auto shredder residue potential fuel for steel mill blast furnaces.” 

Canadian Chemical News, September 1, 1999. 

DeGaspari, John. 1999. “From trash to cash: A new process reclaims former unrecoverables in 

the residue of scrapped vehicles.” Mechanical Engineering Magazine Online

<http://www.memagazine.org/backissues/membersonly/june99/features/trash/ 

trash.html>. 

Hook, Brian R. 2008. “Auto shredder residue recycling researched.” AmericanRecycler.com 

<http://www.americanrecycler.com/1008/auto.shtml>. 

Nourreddine, Menad. 2007. “Recycling of auto shredder residue.” Journal of Hazardous 

Materials 139(3): 481-490. 

Tai, Hua-Shan, Sheng-Cheng Chang, and Wan-Shan Su. 2006. “Investigation of the Derived 

Fuel Rod Formation from Auto Shredder Residue Using an Extrusion Apparatus.” 

Environmental Progress 25(3): 235-252. 

United States Council for Automotive Research LLC (USCAR). 2008. “Did you know that cars 

are the most recycled product in America?” Press Release of USCAR 

<http://www.uscar.org/guest/article_view.php?articles_id=192>. 

United States Environmental Protection Agency (EPA). 2008. “Automotive Parts,” at Common 

Wastes & Materials <http://www.epa.gov/epawaste/conserve/materials/auto.htm>. 

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