In this paper the results of an analysis of the material intensity of advanced composite materials are presented. The analysis is based on the MIPS-concept of the Wuppertal Institute which allows the calculation of the overall material intensity of products and services. It can be shown that the production of one kg of E-Glass fibers is connected with the consumption of 6.2 kg materials, 95 kg water and 2.1 kg oxygen which is of similar size compared to the inputs required in steel production. Material inputs required to produce one kg of p-aramid are 37 kg of materials and 19.6 kg air. Values for carbon fibers are even higher yielding to 61.1 kg of abiotic materials and 33.1 kg of air. Similarly, the production of epoxy resins is connected with larger material flows than the production of polyester resins. Of core materials, inputs per kg for PVC foam exceed those in PUR-foam production by a factor of 1.4 in water to 2.3 in abiotic material consumption. However, ecologically decisive are not the inputs per kg but the material input per service unit. Therefore, the material input per service unit computed for the body of a passenger ship and a robot arm are compared with alternative steel and aluminium versions. Both examples show that in the case of significant inputs during the user phase of products, even a more material intensive investment in the production phase can yield significant ecological benefits over the whole life-cycle compared to metal versions. Improvements can easily reach a factor of two albeit significant potential for engine optimizations have still been neglected. Results already include the actual recycling quota of metals whereas for composites only virgin material has been calculated as any form of real recycling does not actually exist but only certain types of downrecycling. Of those treatment options, first material recycling and second the use in blast furnaces would lead to better results in resource productivity than incineration and landfills. The paper finally draws some conclusions about the potential advantages of material substitution in the automotive industry. Due to the rather short real operation time of cars during their user phase - around six months - an investment in advanced composite materials in car production only results in a significant improvement of the overall eco-efficiency of cars if it allows a substantial weight reduction of the overall vehicle.
Material Intensity of Advanced Composite Materials
Results of a study for the Verbundwerkstofflabor Bremen e.V.
Wuppertal Paper no. 90 (February 1999)