By ETH Zurich
. . . The new procedure uses the sun’s thermal energy to convert carbon dioxide and water directly into synthetic fuel.
“This allows solar energy to be stored in the form of chemical bonds,” explains Ivo Alxneit, chemist at the PSI’s Solar Technology Laboratory. “It’s easier than storing electricity. . . . ”
When subjected to very high temperatures above 1500 °C, cerium oxide loses some oxygen atoms. At lower temperatures, this reduced material is keen to re-acquire oxygen atoms. If water and carbon dioxide molecules are directed over such an activated surface, they release oxygen atoms (chemical symbol: O). Water (H2O) is converted into hydrogen (H2), and carbon dioxide (CO2) turns into carbon monoxide (CO), whilst the cerium re-oxidizes itself in the process, establishing the preconditions for the cerium oxide cycle to begin all over again.
The hydrogen and carbon monoxide created in this process can be used to produce fuel: specifically, gaseous or fluid hydrocarbons such as methane, petrol, and diesel. Such fuels may be used directly but can also be stored in tanks or fed into the natural gas grid. . . .
Using various standard methods of structure and gas analysis, researchers working in laboratories at the PSI and the ETH in Zurich examined the cerium-rhodium compound, explored how well the reduction of the cerium oxide works and how successful methane production was. “So far, our combined process only delivers small amounts of directly usable fuel, but we have shown that our idea works and it’s taken us from the realms of science fiction to reality.”