hydrogen, zero emission, microwave, biomass
The share of hydrogen in the energy market is increasing with the implementation of fuel cell systems and the growing demand for zero-emission fuels. One major challenge is a distribution system for hydrogen. This drawback could be overcome by a decentralised hydrogen generation technology based on biomass conversion via a novel type of steam-iron process, described in this paper. In the first step a CO and H2 containing syngas from bio mass reacts with Fe2O3, Fe3O4 or FeO to produce an iron sponge. In the second step the reduced iron is re-oxidised with steam to form magnetite (Fe2O3) and hydrogen. Opposite to the State of the Art technology an integrated high yield, small scale hydrogen generator is obtained, by direct combining the biomass (wood chips) gasification process with a sponge iron process for hydrogen production. The reactor consists of separate gasification, reduction and oxidation zones. The pre-heating and temperature adjustment is done by microwave radiation of 2.45 GHz. Under isothermal conditions at 800°C, the oxidation rate is approximately two times higher than the reduction rate. By the use of pulsed microwave power the reaction rate can be adjusted in a way, that the reduction and oxidation cycle are in the same time frame to enable quasi continuous hydrogen production. In the presented paper the detailed apparatus concept, the potential applications as well as the energy balance of the process will be discussed.