Karl Kordesch

Hydrogen production by steam–iron process

The steam-iron process is one of the oldest methods of producing hydrogen. It is a cyclic process for water cleavage, whereby coal is consumed. Coal is gassified to a lean reducing gas, containing carbon monoxide and hydrogen. This gas reacts with iron oxides (haematite Fe 2 O 3 , magnetite Fe 3 O 4 , wuestite FeO) to produce a reduced form of iron oxide (wuestite FeO, iron Fe). The reduced iron oxide is re-oxidised with steam to form magnetite and hydrogen. After studies concerning theoretical limitations, the subsequent practical realisation by construction of a suitable laboratory prototype reactor was performed. Further, the investigation and optimisation of process variables, accompanied by respective chemical analyses, and finally the simulation of the whole process and the design of a demonstration plant for electricity generation system in the range of 10 MW were carried out. The resulting overall efficiency (heat and electricity) of the respective power plant was calculated as 35% and the electrical efficiency at about 25%. The operation of the small scale Sponge Iron Reactor (SIR) showed that the hydrogen produced is sufficiently pure for use in any kind of fuel cell (CO < 10 ppm).

Alkaline fuel cells applications

Abstract On the world-wide automobile market technical developments are increasingly determined by the dramatic restriction on emissions as well as the regimentation of fuel consumption by legislation. Therefore there is an increasing chance of a completely new technology breakthrough if it offers new opportunities, meeting the requirements of resource preservation and emission restrictions. Fuel cell technology offers the possibility to excel in todays motive power techniques in terms of environmental compatibility, consumers profit, costs of maintenance and efficiency. The key question is economy. This will be decided by the costs of fuel cell systems if they are to be used as power generators for future electric vehicles. The alkaline hydrogen–air fuel cell system with circulating KOH electrolyte and low-cost catalysed carbon electrodes could be a promising alternative. Based on the experiences of Kordesch [K. Kordesch, Brennstoffbatterien, Springer, Wien, 1984, ISBN 3-387-81819-7; K. Kordesch, City car with H2–air fuel cell and lead–battery, SAE Paper No. 719015, 6th IECEC, 1971], who operated a city car hybrid vehicle on public roads for 3 years in the early 1970s, improved air electrodes plus new variations of the bipolar stack assembly developed in Graz are investigated. Primary fuel choice will be a major issue until such time as cost-effective, on-board hydrogen storage is developed. Ammonia is an interesting option. The whole system, ammonia dissociator plus alkaline fuel cell (AFC), is characterised by a simple design and high efficiency.

Intermittent use of a low-cost alkaline fuel cell-hybrid system for electric vehicles

Abstract Alkaline fuel cell (AFC) hybrids with the capability to shut down completely between uses (by draining the circulating KOH electrolyte) can expect an operating life of about 4000 h, which is equivalent to 200,000 km of driving, They should be able to compete on cost with heat engines (US

The mechanism of capacity fade of rechargeable alkaline manganese dioxide zinc cells

50 to US

Development of low cost alkaline fuel cells

100 per kW). An early model is the hydrogen/air fuel cell lead–acid hybrid car, built by K. Kordesch in the 1970s. Improved air electrodes plus new variations of the bipolar stack assembly developed in Graz, make success probable. In cooperation with Electric Auto (EAC), an ammonia cracker is also in development. A RAM™ battery–AFC hybrid combination has been optimized.

Degradation modes of alkaline fuel cells and their components

Abstract Recent experiments showed, that in contrast to traditional opinion, if the cathode was protected by anode limitation the capacity fade of Rechargeable Alkaline Manganese Dioxide Zinc (RAM™) cells was not caused by the EMD cathode, but by the gelled zinc anode. The key is the electrolyte. The cathode competition for the electrolyte and the increasing requirement of chemically formed ZnO for more electrolyte caused an electrolyte deficiency at the front face of the anode and finally caused precipitation of zincate and passivation of zinc. The crust is a mixed material of precipitation and passivation products. The low solubility ZnO is formed by decomposition of electrochemically generated zincate ions [Zn(OH) 4 ] 2− and also by recombination of zinc with oxygen during overcharge. The progressively thickened “crust” at the front face of the anode increases the resistance, then finally causes the cell to fade. The crusting is a redistribution of active material and electrolyte between the front and rear of the cylindrical gelled zinc anode. More electrolyte and proper charging can delay such a “crusting” phenomenon.

Structural analysis of alkaline fuel cell electrodes and electrode materials

Abstract Fuel cells as direct energy converters will find wide application in a future hydrogen economy. At the Institute for Hydrogen Systems (IHS) emphasis was placed on designing a mass producible, low, cost, alkaline, bipolar fuelcell. Carbon-filled plastics are used in the construction of the fuel cell stack. Teflon bonded, multi ayer carbon electrodes have been developed. The pretreatment of carbon materials proved necessary to prolong the life of the electrodes. Electrocatalysis work resulted in the replacement of the noble metal electrocatalyst of the cathode and a significant reduction in the loading of the anode. The material cost of the alkaline, bipolar hydrogen-air fuel cell currently stands at Can

Identification of organic corrosion inhibitors suitable for use in rechargeable alkaline zinc batteries

250 (US

Triethanolamine as an additive to the anode to improve the rechargeability of alkaline manganese dioxide batteries

175) per kW.

A study of rechargeable zinc electrodes for alkaline cells requiring anodic limitation

Abstract The performance and life-limiting parameters of multilayer polytetrafluoroethylene (PTFE) bonded carbon air cathodes and hydrogen anodes, developed at the Institute for Hydrogen Systems (IHS) for use in low temperature alkaline electrolyte fuel cells (AFC) and batteries, were investigated. Scanning electron microscopy (SEM), X-ray energy spectroscopy (XES), electron spectroscopy for chemical analysis (ESCA), microcalorimetry and intrusion porosimetry techniques in conjunction with electrochemical testing methods were used to characterize electrode components, electrodes and alkaline fuel cells. The lifetime of air cathodes is mainly limited by carbon corrosion and structural degradation, while that of hydrogen anodes is frequently limited by electrocatalyst problems and structural degradation. The PTFE binder was also found to degrade in both the cathodes and the anodes. The internal resistance, which was found to generally increase in AFCs in particular between the cathode and the current collector, can be minimized by the proper choice of materials. Temperature cycling of AFCs may result in mechanical problems; however, these problems can be overcome by using AFC components with compatible thermal expansion coefficients.