A promising method for the conversion and storage of solar energy into hydrogen is the dissociation of water into oxygen and hydrogen, carried out via a two-step process using metal oxide redox systems such as mixed iron oxides, coated upon multi-channeled honeycomb ceramic supports capable of absorbing solar irradiation, in a configuration similar to that encountered in automobile exhaust catalytic converters. With this configuration, the whole process can be carried out in a single solar energy converter, the process temperature can be significantly lowered compared to other thermo-chemical cycles and the recombination of oxygen and hydrogen is prevented by fixing the oxygen in the metal oxide. For the realization of the integrated concept, research work proceeded in three parallel directions: synthesis of active redox systems, manufacture of ceramic honeycomb supports and manufacture, testing and optimization of operating conditions of a thermochemical solar receiver-reactor. The receiver-reactor has been developed and installed in the solar furnace in Cologne, Germany. It was proven that solar hydrogen production is feasible by this process demonstrating that multicycling of the process was possible in principle.

Welche Bedeutung hat Arbeitsverdichtung in den verschiedenen Branchen? Und wie hängt sie mit weiteren Entwicklungen der Arbeitswelt zusammen? Das Risikoobservatorium der DGUV gibt Einblicke in verschiedene Branchen sowie Hinweise auf mögliche Stellschrauben, um gesundheitsgefährdenden Auswirkungen von Arbeitsverdichtung entgegenzuwirken.

The comprehensive liberalisation of the electricity market at the end of the last century has initiated a dynamic development. The politically determined disjunction of the network operation from generation, commerce and distribution which broke open the value added chain concerning the business organisation is to induce competition and consequently lower prices. Thus, besides a secure electricity supply, profitability, efficiency, quality and environmental aspects constitute present aims and have led to an enormous increase of complexity in the power supply. Furthermore, the imponderability and uncertainty of competition processes in a liberated market aggravate prognoses for future investment decisions. Not least the anymore rising electricity demand, the emerging of a single European power market as well as technically pushed changes in the production structure, due to the emergence of alternative forms of power generation such as wind or solar energy, biomass energy or fuel cells, account for electric networks which afford complex planning and regulation mechanisms. This article gives a survey of various requirements posed on electricity networks and concludes with a short description of solution approaches to safeguard a cost-saving and secured future electricity supply.

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