4 Conclusion

An economical analysis of stack fabrication costs, based upon the experience gathered from the first Danish 1/2 kW stack shows, that if an area specific internal resistance of 0.4 iîcm2 may be achieved, the stack may be fabricated at 3000 ECU/kW. The fabrication is based upon simple ceramic techniques. This cost is already a major reduction compared to the price published by the European Community III of 30,000 ECU/kW. A number of tools have been identified for further reduction of the stack price: (i) redesign of costly components, (ii) utilisation of cheaper materials where acceptable, (iii) reduction of the number of different components in the stack, and (iv) reduced losses in a highly automated, large scale production. Calculations excluding (iv) show that a reduction to -1100 ECU/kW is possible. This, however, requires further technological development of the shaping of selected components. More than 40% of the 1100 ECU/kW is capital cost and less than 25% is materials cost. A significant further reduction of the cost towards the assumed commercialisation limit of 500 ECU/kW will have to address a general reduction of the internal stack resistance, as this factor will influence all fabrication costs in the desired direction.

Technically the dimensional instability of the interconnect has to be focused upon, because single sided material expansion during p02-changes on the anode side during service will lead to sealing problems and detachment of contacts between the individual stack elements. Presently available metallic interconnect materials are not directly applicable, partly because of high materials cost and high cost of shaping, partly because of the requirement of lower operation temperatures to reduce oxidation and Q2O3 poisoning of electrodes. Finally, it is mandatory that an anode either with an adjusted internal reforming rate or with the ability of direct methane oxidation is developed.

0 0

Post a comment