Zinc–zinc oxide cycle

The Solzinc process is a project funded by the European Union thermochemical process for hydrogen production from water by means of zinc and solar energy. The goal is the storage of solar energy in the form of metallic zinc. The method has been in the laboratory for solar technology in Swiss Paul Scherrer Institute (PSI) developed at ETH Zurich.

Process steps

The method consists essentially of two steps. In the first step, zinc oxide is thermally by solar energy (eg solar tower power plants ) is cleaved into zinc and oxygen:

To reduce the time necessary for the production of metallic zinc temperature, may optionally be up to 15 % of the stoichiometric amount of carbon is present as a reducing agent in accordance with:

The reaction temperature drops from about 1800 ° C. to about 1200 ° C.

In the second step, the zinc thus obtained is reacted with water to form zinc oxide and hydrogen:

This reaction is exothermic and proceeds at about 350 ° C.

The efficiency of the process in 2005 was in the pilot plant at the Weizmann Institute of Science 30 %, but it is through process optimization, an efficiency of 60 % is expected. The generated hydrogen is used by burning for energy. The zinc may alternatively be used in zinc -oxygen fuel cell for generating electricity. Concepts for large-scale use have already been developed.

If it is omitted, the addition of carbon ( zinc oxide ) method, the design effort for the reactor increases., It is advantageous, however, that the process runs without emitting carbon dioxide. The carbon monoxide produced directly at carbon addition would only allow a neutral CO2 balance sheet when it is used for chemical syntheses in which it replaces other fossil CO2 sources.