A hydrogen production process has been developed using solar refined zinc. Hydrogen can be extracted from water by heating water to 350°C (662°F) in the presence of zinc. The problem is that zinc is produced by either electolysis or smelting, both processes having a high energy consumption and concurrent pollution resulting from the consumption of fossil fuels used to oproduce the energy. Production of hydrogen by electrolysis of water requires even more energy and using the current technology of making it from natural gas would require too much of this resource to be used to produce the large quantities of hydrogen needed to run our cars using fuel cells.
Scientists from Israel, Sweden and France have collaborated to develop a method of producing the required pure Zinc from the naturally occuring ore of zinc, zinc oxide (ZnO). Zinc must normally be heated to 1750°C / 3182°F to recover the zinc. Scientists at the Weitzman Institute in Israel found that adding small amounts of carbon in the form of coal enabled Zinc production at a more manageable 1200°C (2192°F). A 1 MW solar furnace (shown above) was used to generate the required temperatures. A large array of heliostats (computer guided highly reflective mirrors) follows the sun around the sky and reflects the light to a hyperbolic mirror located inside the solar tower producing highly concentrated heat inside the solar furnace located in the tower. Zinc was produced at rates which reached an average of 50kg/hr during the tests, so that scale up to commercial production quantities should be relatively easy.
When heated above 1200°C the ZnO breaks down into Zn and oxygen which in turn recombines with the carbon to create CO as a minor by-product. In order to produce hydrogen from the Zn powder a much simpler process is performed where the Zn is mixed with water at a temperature of 350°C. The oxygen inside the water recombines with the Zn to produce ZnO once again and the by-product is pure hydrogen. The later process could be performed at the local filling station where the hydrogen is needed, while zinc could be produced at locations where solar heat can be produced the most economically.
Resouce: "ZINC POWDER WILL DRIVE YOUR HYDROGEN CAR", Isra Cast, 9/8/05