United States Environmental Protection Agency Industrial Environmental Research Laboratory Cincinnati OH 45268 Research and Development EPA-600/S2-82-103 Mar. 1983 Project Summary Status, Trends and Implications of Carbon Fiber Material Use Benjamin L Blaney This study estimates the future usage of carbon fiber composite materials in both consumer and industrial products, and the resultant economic impact of the disposal of these products and indus- trial scrap in both the municipal and industrial waste streams. The technical and economic substitutability of carbon fiber composite materials for materials now in use is analyzed, and the major uses of this material forecasted. Poten- tial problems relating to the disposal of products containing carbon fiber mate- rials are analyzed, and estimates are made of the economic impacts of the disposal of these products for alterna- tive scenarios that cover a wide range of disposal technologies. The economic impact of the disposal of products and industrial scrap containing carbon fiber composite materials is found to be small for all of the scenarios investi- gated. This Project Summary was developed by EPA's Industrial Environmental Re- search Laboratory, Cincinnati^ OH, to announce key findings of the research project that is fully documented in a separate report of the same title (see Project Report ordering information at back). Introduction Carbon fiber is produced by subjecting polyacrylonitrile or petroleum pitch fibers to high temperature and pressure. The resultant fibers have a graphitic molec- ular structure which makes them high in tensile strength, light in weight, and resistant to corrosion. Fibers are also good electrical conductors and do not readily oxidize except at high temper- atures. Carbon fiber composite materials are made by binding the fibers in a thermosetting or thermoplastic resin ma- trix. Currently, composites are predomi- nately used in the transportation sector (e.g. for aircraft parts). They are also used for the construction of prostheses and other consumer goods such as golf clubs and tennis racquets. Because of some of the carbon fibers, properties of their release into the atmosphere could result in unfavorable environmental impacts. The objective of this study was to deter- mine whether the disposal of consumer goods or industrial products containing carbon fiber reinforced plastics ("carbon fiber composite materials") would result in environmental impacts of economic consequence. This study investigated the economic and technical incentives for the use of carbon fiber materials, projecting demand to 1990. It identified the life cycle of different categories of carbon fiber prod- ucts and determined the disposal paths for each. Since the useful lives of these products range from five to 10 years for sports equipment to 20 or more years for aerospace items, most of the carbon fiber produced in 1990 will not enter the waste stream until the early 2000s. It can therefore be assumed that the carbon fiber disposal rate will be equal to or less than the 1990 production rate for 10 to 15 years after 1990. This period is referred to in the report as "post-1990." The study projected the annual economic impact of carbon fibers released from waste dis- posal during this time. ------- For the purpose of this study, carbon fiber refuse was aggregated into two groups: that which entered municipal waste streams and that which was dis- posed of in industrial waste streams. Points of release to the environment were identified and estimates were made of annual fiber release rates for each of the waste streams. With the use of previously published risk assessments which deter- mined the impacts of carbon fibers in the environment as a function of fiber release, estimates were made of the cost (in dollars) arising during the disposal of carbon fiber composites. Because carbon fibers are good elec- trical conductors and are very light weight, they may be dispersed over a large area and could damage electrical equipment. The study therefore focused the cost analysis on electrical failures arising from carbon fibers released during disposal. Only the impacts of incinerating carbon fiber composite material were addressed. Those associated with incinerating raw carbon fiber or preimpregnated carbon fiber materials were not analyzed, be- cause manufacturers were found to be aware of potential hazards associated with incinerating these materials and to use other disposal techniques. Also, because of the high cost of carbon fiber, steps have been taken to minimize the amount of scrap from these materials. Health hazards from carbon fiber re- lease were not considered in this study because the extant health effects data when the study was performed were insufficient for the derivation of risk functions. The results of this report are based on calculations which use a number of engineering estimates. Besides projec- tions of future demand for carbon fiber composite materials, estimates were made of scrap disposal pathways, incin- erator release rates, pollution control equipment efficiencies, and electrical damage functions. Conservatively high estimates of carbon fiber use, and fiber release rates were used to indicate an upper limit to potential impacts. Ten disposal scenarios were considered to account for varying percentages of com- posite scrap recycled, landfilled, or incin- erated. Findings and Conclusions Future Composite Use There are many current and potential applications for carbon fiber composites in both consumer and industrial sectors. The extent to which composites will be substituted for conventional structural materials will be determined by their cost effectiveness, which varies from applica- tion to application. Composites will be used in consumer goods when the buyer is willing to pay the extra cost (often twice the current price of alternative materials) for durability and light weight. In the transportation sector, composites will be used because they are corrosion resistant and because their high strength-to-weight and stiffness-to-weight ratios can result In fuel savings. Table 1 shows projected carbon fiber demand for various industrial sectors to 1990. It can be seen that in the near- term, the aerospace industry will be the principal user of composites, while to- wards the end of the 1980s, demand in the automobile industry is expected to increase substantially. Demand for fibers in sporting goods and for miscellaneous applications is not expected to grow as rapidly. Three principal benefits result from using carbon fiber in the transportation sector. First, production costs are reduced because of design simplification. Second- ly, carbon fiber composites have a longer life in many applications and therefore reduce maintenance costs. Thirdly and most importantly, carbon fiber use saves fuel. If graphite springs are used for double-axle trucks, it is estimated that body weight would be reduced by 272 pounds, resulting m pre- tax profits in the range of $100 to $800 pertruck. If graphite sidewalls, partitions, celling and stowage bins are used in a fleet of 1,383 three-engine Boeing 767s, it is estimated that $60 million would be saved from reduced fuel consumption during the lifetime of the fleet. (Note that the carbon fiber used in this fleet is 2 percent of the total estimated industrial fiber use in 1990; the use of carbon fiber in other transportation vehicles should further increase fuel savings.) Table 1. Disposal of Composite Materials Carbon fiber entering the municipa waste stream is expected to be composec primarily of discarded consumer products (In this study, automobile disposal is considered under industrial waste streams. Most sports equipment manufacturer; produce little composite scrap (in the 1 tc 5 percent range), because composit* costs are high and manufacturers attemp to minimize waste by designing efficiently and by turning scrap into marketabk items. The same appears to be true fo manufacturers of other consumer goods Therefore, the contribution from consum er goods manufacturers to municipa waste is essentially negligible. Approxi mately 5OO kg of carbon fiber composit* enter the municipal waste stream annu ally from the disposal of consumer goods Industrial scrappage, used industria products, and oversized consumer prod ucts enter the industrial waste stream The quantity of fiber consumed (and thus disposed of) throughout the industria sector is much larger than that used ir consumer goods. Nine percent of th« carbon fiber produced in 1980 was fabri cation scrap and thus entered the indus trial waste stream immediately, while 6^ percent was used in industrial products The remainder went to consumer goods Thus about 73 percent of the fiber pro duced will eventually enter the industria solid waste stream. It is estimated tha approximately 82 percent of the carbor fiber produced in 1990 (about 720( tonnes) will eventually enter the indus trial refuse stream. Waste Disposal Paths The method of disposal of municipa and industrial waste is an importam determinant of the likelihood that fibei will be released and thus that the envi- ronment will be affected. As of 1980 the U.S. Carbon Fiber Demand Projections Through 1390, 1000 Kilograms 11000 Pounds)* Demand Year Sector 1980 1983 1985 1990 Aerospace Sporting Goods Automobile Other Industries Totals 182 (400) 141 (310) 6(141 87(192) 416(916) 591 (1300) 227 (500) 45(100) 159 (350) 1022(2250) WOO (2200) 318(700) 91 (200) 227 (500) 1636(3600) 2273 (5000) 591 (1300) 4545 (10000. 409 (900) 7818(17200, 'Source: Composite Market Reports. Inc., "Annual Market Estimate for Graphite, Prepreg am Fiber, 1979 through 1985," (1980), and personal communications. ------- disposition of municipal waste was as follows: • 89 percent landfill • 4 percent incinerated without recov- ery • 1 percentincmeratedforenergyrecov- ery • 6 percent source separation Many pressures, including increases in energy costs, shortages in land available for landfill, and environmental concerns favor changing this mix in the future. These pressures were accounted for when environmental impacts were pro- jected in terms of several different sce- narios for future municipal waste dispos- al. The manufacturers of fiber tend to recycle, reuse or otherwise limit the amount of scrap produced. Many recycle the carbon fiber scrap by chopping it up. When disposal is necessary, some type of container is used to segregate the fiber from other industrial wastes. Subsequent- ly, the containers are usually placed in landfills, although they are occasionally stored. It was estimated that only 0.5 percent of the carbon fiber used by industry now enters the industrial waste stream. Future incineration trends are reflected in five industrial waste disposal scenarios in the full report. Most carbon manufacturers and pre- impregnators are conscientious in advis- ing their customers about handling car- bon fiber material. Some attach labels stating acceptable disposal procedures, whereas others recommend recycling. In general, the aerospace industry takes appropriate precautions when dis- posi ng of carbon fiber scrap. The firms are knowledgeable about the properties of carbon fiber and composites. Many aero- space firms generate a substantial amount of scrap but have not instituted recycling programs. Most scrap is segregated and landfilled. Some companies cure their scrap into blocks, whereas others put the scrap into 55 gallon drums. The amount of scrap produced by the remaining users of carbon fiber is small. Many of these companies are in the research and development stage and use very little carbon fiber. Companies already producing carbon fiber generally landfill the scrap. Industrially used products containing carbon fiber range from loom shuttles to both structural and non-structural parts of commercial aircraft. Disposal of these products varies, depending on the appli- cation. Because of the tight manifest control system maintained for all military and commercial airplane parts in this country, disposal is generally through landfilling, not incineration. Automobiles are scrapped and non-recyclable parts such as those made of carbon fiber are landfilled. In the future, approximately 10 percent of the carbon fiber used in automobiles may reach the municipal waste stream after being discarded by repair shops, specialty body shops, and the like. Carbon fiber products used in non-transportation industries will be dis- carded with other industrial waste. Release Mechanisms and Cost Impacts Carbon fibers are released during dis- posal principally from incinerators. Be- cause carbon fibers are oxidized only at high temperatures (above 1000°C), the composite matnx(e.g.,athermosetresin) is rapidly destroyed during combustion and fibers may be entrained in combus- tion gases and emitted from the stack of the incinerator Two other potential fiber release mech- anisms were shown to be insignificant. One was from fires in landfills and the other was due to explosions in waste shredding operations. A third release mechanism, paniculate emissions from waste shredding operations, is being investigated further by the U.S. EPA. Estimated fiber release rates from municipal mass-fired incinerators with various pollution control and waste heat recovery equipment are shown in Table 2. The fiber release rate from incinerators is affected by the type of incinerator, pollu- tion control equipment, and waste heat recovery equipment employed. The re- lease rates were calculated assuming a conservatively high upper bound to the uncontrolled fiber release of 4 percent (i.e. 4 kg of fibers released per 100 kg of composite incinerated). The estimated annual average econom- ic impact arising from the disposal of Ttble 2- Fiber Release Rates for Municipal Incinerators with Various Forms of Paniculate Control Stack Release Particle Control of Free Fibers System (%) No Active System (Cyclone) 3.6 Bag House 0.04 Wet Scrubber 1.2 Electrostatic Precipitator 0.8 (ESP) Heat Recovery and ESP 0.24 carbon fiber in municipal waste streams is very small, as shown fn Table 3. The upper bound case—Scenario 5—assumes that all municipal waste would be incin- erated, requiring over 900 new, large incinerators. This incineration rate is unlikely in the 1990s. Industrial incineration will take place predominately in multi-chamberandstarved- air units, with lesser use of fluidized bed, multi-hearth, rotary kiln and single cham- ber incinerators. Release rates for both multi-chamber and starved-air units were estimated to be 0.12 percent and 0.36 percent, with and without waste heat recovery units. A much larger volume of composite material may enter the waste stream at a manufacturing plant or may be discarded as part of the transportation equipment waste stream. Table 4 shows the econom- ic impacts obtained from the five sce- narios for type and volume of industrial waste disposal. The most likely upper bound to fiber release is represented by Scenario D, in which 10 percent of the composite material in automobiles is incinerated along with all industrial waste from non-aerospace industries. This sce- nario also reflects the incinerator mix likely to be used by industry in the 1990s and shows a very small economic impact from carbon fiber disposal. Table 3. Comparison of Scenarios Considered for Composite Disposal in Municipal Sector 1. 2. 3. 4. 5. Scenario Baseline Case Near Future Case Far Future Case Intensive Energy Recovery Case Upper Bound Case Total Number of Incinerators 41 51 39 487 989 Percent of Refuse Burned 4 5 a 60 100 Carbon Fiber Burned (Kg/Day) 80 100 160 1.200 2.000 Annual Cost $ 1.693 $ 1.828 $ 1.197 $ 6.795 $27.306 ------- To determine an extreme upper bound to economic impacts of carbon fiber disposal in the industrial waste stream, it was assumed in Scenario E that all carbon fiber used in industry was incin- erated and that incineration occurred using the least efficient incinerators considered in this study (i.e. municipal incinerators with no active controls). The resultant annual cost of approximately two million dollars is still low compared to benefits of carbon fiber (e.g. fuel savings). In any case, it is highly unlikely that all carbon fiber composite used in industry will be disposed of through incineration or that incinerators with such high emis- sion rates will be used. Table 4. ' Comparison of Scenarios in Industrial Sector A B C D E Scenarios Baseline Case Future Trend Case Current Upper Bound Future Upper Bound Worst Possible Case Disposal Practices Current' Current Aerospace Scrap Landfilled J 0% A utomobile + 1 00% All Other Industrial Waste Incinerated Aerospace Scrap Landfilled 1 0% A utomobile + ; 00% A II Other Industrial Waste Incinerated All Industrial Waste Incinerated Incinerator Population Current No Single Chamber Current No Single Chamber Least Efficient Type (Municipal) Paniculate Control None With Heat Recovery (+Wet Scrubbers) None With Heat Recovery t+Wet Scrubbers) None Cost Pei Year ($) 5,250 466 131.351 11.660 1,907.999 BAs of 1980. This Project Summary was prepared by staff of Econ, Inc., Princeton, NJ 08540; the EPA author Benjamin L. Blaney (also the EPA Project Officer, see below) is with the Industrial Environmental Research Laboratory. Cincinnati, OH 45268. The complete report, entitled "Status, Trends and Implications of Carbon Fiber Material Use," (Order No. PB 83-147 751; Cost: $ 16.00, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Industrial Environmental Research Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 UU.S. Government Printing Office. 1983-659-017/7025 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati OH 45268 Postage and Fees Paid Environmental Protection Agency EPA 335 Official Business Penalty for Private Use $300 RETURN POSTAGE GUARANTEED Third-Class Bulk Rate IERL0120766 LIBRARY REGION V U.S. EPA 230 S DEARBORN ST CHICAGO IL 60604 * * ------- |