Solar Chemical
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Solar radiation stimulated chemical processes use solar energy to drive chemical reactions. They offset energy that would otherwise require an alternate source and can convert solar energy into a storable and transportable fuel. Solar induced chemical reactions can be divided into thermochemical or photochemical.

Hydrogen production technologies involving the use of solar light have been a significant area of research since the 1970s. Aside from electrolysis driven by photovoltaic or photochemical cells, several thermochemical processes have been explored. One such route uses concentrators to split water at high temperatures (2300-2600 °C), but this process has been limited by complexity and low solar-to-hydrogen efficiency (1–2%). Another approach uses the heat from solar concentrators to drive the steam reformation of natural gas thereby increasing the overall hydrogen yield.

Thermochemical cycles characterized by the decomposition and regeneration of reactants present another avenue for hydrogen production. The Solzinc process under development at the Weizmann Institute uses a 1 MW solar furnace to decompose zinc oxide (ZnO) at temperatures above 1200 °C. This initial reaction produces pure zinc, which can subsequently be reacted with water to produce hydrogen. Sandia''s Sunshine to Petrol (S2P) technology uses the high temperatures generated by concentrating sunlight along with a zirconia/ferrite catalyst to break down atmospheric carbon dioxide into oxygen and carbon monoxide (CO). The carbon monoxide can then be used to synthesize methanol, gasoline and jet fuel.

Photoelectrochemical cells or PECs consist of a semiconductor, typically titanium dioxide or related titanates, immersed in an electrolyte. When the semiconductor is illuminated an electrical potential develops. There are two types of photoelectrochemical cells: photoelectric cells that convert light into electricity and photochemical cells that use light to drive chemical reactions such as electrolysis. A photogalvanic device is a type of battery in which the cell solution (or equivalent) forms energy-rich chemical intermediates when illuminated. They then can react at the electrodes to produce an electric potential. The ferric-thionine chemical cell is an example of this technology.