Recycling fuel cell materials

Note This chapter is a revised and extended version of Chapter 13 Recycling and life cycle assessment of fuel cell materials by J. Smith Cooper, originally published in Materials for Fuel Cells, ed. M. Gasik, Woodhead Publishing Limited, 2008, ISBN 978-1-84569-330-5. 

Recycling and life cycle assessment of fuel cell materials 119... 

Recycling concepts for fuel cell components. Since fuel cells include valuable materials, recycling practices should be developed and demonstrated, including ... 

Concepts such as molten carbonate or solid oxide fuel cells are not expected to reach a commercial stage during the next decade. Preliminary cost estimates for a possible commercialisation are at 3200 US kW by 2010, declining to 1300 US kW by 2050, according to a recent assessment of available data (Fukushima et al, 2004). Problem areas include the availability of La, a material currently used in high-temperature ceramics. Recycling should be pursued to a high rate. 

Chemical engineers do much of the ongoing fuel-cell research. There are many careers open to chemical engineers. They can work to find alternative, renewable fuel sources, to design new recyclable materials, and to devise new recycling methods. These scientists combine knowledge of chemistry, physics, and mathematics to link laboratory chemistry with its industrial applications. As with any scientist they also must be good problem solvers. 

For at least the first half of the 21st century the world will continue to rely heavily on petroleum and coal as fuels and as hydrocarbon sources for use in making polymers, etc. Improved versions of existing catalysts, as well as new catalysts/processes, will be vital in making an orderly transition from reliance on nonrenewable resources. Included in this will be the continued development of practicable fuel cell technology and processes for synthesizing clean fuels from coal, tar sands, etc. Catalysis will play a role in the shift toward increased use of renewable/recycled materials and in efforts to minimize air pollution. Catalysts that mimic... 

Palladium is an expensive metal and this imposes limits on the thickness of material that can be used for hydrogen purification in competition with other industrial methods. Emonts et al. estimated that films less than about 5 p,m in thickness need to be used in a fuel-cell methanol reformer [7], while Criscuoli et al. [8] concluded that 20 p,m is an upper limit for membranes to be economically competitive. These economic estimates overlook the possibility of recycling the palladium or palladium alloy. This becomes a very real possibility in the use of free-standing membranes rather than composite structures with other metals or ceramics. Recycling prospects probably increase the thickness constraint to something between 5 jxm and 8 p.m, a value that is also consistent with factors such as limitations on the volume of space occupied by a multiple membrane assembly. 

The removed sulfur of both processes can be recycled. The recycled sulfur can be used for building materials. So both processes for the desulfurization are sustainable. The decision which process for the desulfurization will be used in fuel-cell heating appliance is the outcome of a consideration between maintenance costs and invests. 

There is no doubt that the perfluorinated ionomer membranes take initiative in this field and contribute a great deal in the commercialization and wide diffusion of fuel cells in the early stage. In terms of environmental compatibility (recyclability or disposability) and production cost, the perfluorinated ionomer membranes should be replaced with non-fluorinated alternative materials within the next decade. Challenge is how to achieve comparable conductivity and durability with the non-fluorinated membranes. Currently, no alternative materials have overcome the trade-off relationship between these two conflicting properties. In addition to the... 

Fuel cells are an evolving technology and require a very different set of materials for the core system parts (especially the fuel cell stack) than today s power generating equipment. Consequently, many manufacturing processes are involved which are not yet fully commercialized or well characterized. Moreover, the options for end-of-life material reclamation, recycling, and disposal are less well defined today than for other power equipment. 

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