this report presents a detailed assessment of an 80 kw iron- air traction battery system based on the present state of the art. the overall system design and all the component parts are carefully considered before preparing a final specification for a datum system. mathematical models are developed which enable the technical and economic characteristics of the datum system to be computed as a function of component design, size and performance. the models are also used to examine inter-relationship and trends around the datum point. the 80 kw datum system has the following main characteristics: stored energy-200 kwh (net traction); weight-2,092kg; volume-1.1 to 1.5 m3; energy density-95 wh kg-1; peak power density-38 w kg-1; capital cost (power)- 57 kw-1; capital cost (energy)- 22.8 kwh-1; comparisons are made with the lead-acid installation in the dti bus, which is used as the reference application; and with an equivalent diesel engined vehicle. the iron-air system would give 2.5 times increased range with 44 per cent lower weight than the existing lead-acid battery. the economics, which are based on limited quantity production, are less favourable. annual costs are 10-20 per cent higher than lead-acid and 8-11 per cent higher than a diesel weighted for social and strategic factors. if likely improvements are taken into account in a projected system, then a slight economic benefit can be indicated against the weighted diesel. the greatest technical merit of the iron-air battery system is the substantially increased energy/power ratio that it offers compared to lead-acid. it would therefore show to the best advantage in applications where this benefit can be fully exploited. (a)

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